Merge git://git.denx.de/u-boot-dm

21 files changed, 1286 insertions, 398 deletions

diff --git a/test/py/conftest.py b/test/py/conftest.py
index e1674df..3e162ca 100644
--- a/test/py/conftest.py
+++ b/test/py/conftest.py
@@ -29,7 +29,7 @@ log = None
 console = None
 
 def mkdir_p(path):
-    '''Create a directory path.
+    """Create a directory path.
 
     This includes creating any intermediate/parent directories. Any errors
     caused due to already extant directories are ignored.
@@ -39,7 +39,7 @@ def mkdir_p(path):
 
     Returns:
         Nothing.
-    '''
+    """
 
     try:
         os.makedirs(path)
@@ -50,14 +50,14 @@ def mkdir_p(path):
             raise
 
 def pytest_addoption(parser):
-    '''pytest hook: Add custom command-line options to the cmdline parser.
+    """pytest hook: Add custom command-line options to the cmdline parser.
 
     Args:
         parser: The pytest command-line parser.
 
     Returns:
         Nothing.
-    '''
+    """
 
     parser.addoption('--build-dir', default=None,
         help='U-Boot build directory (O=)')
@@ -73,14 +73,14 @@ def pytest_addoption(parser):
         help='Compile U-Boot before running tests')
 
 def pytest_configure(config):
-    '''pytest hook: Perform custom initialization at startup time.
+    """pytest hook: Perform custom initialization at startup time.
 
     Args:
         config: The pytest configuration.
 
     Returns:
         Nothing.
-    '''
+    """
 
     global log
     global console
@@ -190,7 +190,7 @@ def pytest_configure(config):
         console = u_boot_console_exec_attach.ConsoleExecAttach(log, ubconfig)
 
 def pytest_generate_tests(metafunc):
-    '''pytest hook: parameterize test functions based on custom rules.
+    """pytest hook: parameterize test functions based on custom rules.
 
     If a test function takes parameter(s) (fixture names) of the form brd__xxx
     or env__xxx, the brd and env configuration dictionaries are consulted to
@@ -202,7 +202,7 @@ def pytest_generate_tests(metafunc):
 
     Returns:
         Nothing.
-    '''
+    """
 
     subconfigs = {
         'brd': console.config.brd,
@@ -225,28 +225,37 @@ def pytest_generate_tests(metafunc):
             # ... otherwise, see if there's a key that contains a list of
             # values to use instead.
             vals = subconfig.get(fn + 's', [])
-        metafunc.parametrize(fn, vals)
-
-@pytest.fixture(scope='session')
+        def fixture_id(index, val):
+            try:
+                return val["fixture_id"]
+            except:
+                return fn + str(index)
+        ids = [fixture_id(index, val) for (index, val) in enumerate(vals)]
+        metafunc.parametrize(fn, vals, ids=ids)
+
+@pytest.fixture(scope='function')
 def u_boot_console(request):
-    '''Generate the value of a test's u_boot_console fixture.
+    """Generate the value of a test's u_boot_console fixture.
 
     Args:
         request: The pytest request.
 
     Returns:
         The fixture value.
-    '''
+    """
 
+    console.ensure_spawned()
     return console
 
 tests_not_run = set()
 tests_failed = set()
+tests_xpassed = set()
+tests_xfailed = set()
 tests_skipped = set()
 tests_passed = set()
 
 def pytest_itemcollected(item):
-    '''pytest hook: Called once for each test found during collection.
+    """pytest hook: Called once for each test found during collection.
 
     This enables our custom result analysis code to see the list of all tests
     that should eventually be run.
@@ -256,12 +265,12 @@ def pytest_itemcollected(item):
 
     Returns:
         Nothing.
-    '''
+    """
 
     tests_not_run.add(item.name)
 
 def cleanup():
-    '''Clean up all global state.
+    """Clean up all global state.
 
     Executed (via atexit) once the entire test process is complete. This
     includes logging the status of all tests, and the identity of any failed
@@ -272,7 +281,7 @@ def cleanup():
 
     Returns:
         Nothing.
-    '''
+    """
 
     if console:
         console.close()
@@ -282,6 +291,14 @@ def cleanup():
             log.status_skipped('%d skipped' % len(tests_skipped))
             for test in tests_skipped:
                 log.status_skipped('... ' + test)
+        if tests_xpassed:
+            log.status_xpass('%d xpass' % len(tests_xpassed))
+            for test in tests_xpassed:
+                log.status_xpass('... ' + test)
+        if tests_xfailed:
+            log.status_xfail('%d xfail' % len(tests_xfailed))
+            for test in tests_xfailed:
+                log.status_xfail('... ' + test)
         if tests_failed:
             log.status_fail('%d failed' % len(tests_failed))
             for test in tests_failed:
@@ -294,7 +311,7 @@ def cleanup():
 atexit.register(cleanup)
 
 def setup_boardspec(item):
-    '''Process any 'boardspec' marker for a test.
+    """Process any 'boardspec' marker for a test.
 
     Such a marker lists the set of board types that a test does/doesn't
     support. If tests are being executed on an unsupported board, the test is
@@ -305,7 +322,7 @@ def setup_boardspec(item):
 
     Returns:
         Nothing.
-    '''
+    """
 
     mark = item.get_marker('boardspec')
     if not mark:
@@ -322,7 +339,7 @@ def setup_boardspec(item):
         pytest.skip('board not supported')
 
 def setup_buildconfigspec(item):
-    '''Process any 'buildconfigspec' marker for a test.
+    """Process any 'buildconfigspec' marker for a test.
 
     Such a marker lists some U-Boot configuration feature that the test
     requires. If tests are being executed on an U-Boot build that doesn't
@@ -333,7 +350,7 @@ def setup_buildconfigspec(item):
 
     Returns:
         Nothing.
-    '''
+    """
 
     mark = item.get_marker('buildconfigspec')
     if not mark:
@@ -343,7 +360,7 @@ def setup_buildconfigspec(item):
             pytest.skip('.config feature not enabled')
 
 def pytest_runtest_setup(item):
-    '''pytest hook: Configure (set up) a test item.
+    """pytest hook: Configure (set up) a test item.
 
     Called once for each test to perform any custom configuration. This hook
     is used to skip the test if certain conditions apply.
@@ -353,14 +370,14 @@ def pytest_runtest_setup(item):
 
     Returns:
         Nothing.
-    '''
+    """
 
     log.start_section(item.name)
     setup_boardspec(item)
     setup_buildconfigspec(item)
 
 def pytest_runtest_protocol(item, nextitem):
-    '''pytest hook: Called to execute a test.
+    """pytest hook: Called to execute a test.
 
     This hook wraps the standard pytest runtestprotocol() function in order
     to acquire visibility into, and record, each test function's result.
@@ -371,36 +388,45 @@ def pytest_runtest_protocol(item, nextitem):
 
     Returns:
         A list of pytest reports (test result data).
-    '''
+    """
 
     reports = runtestprotocol(item, nextitem=nextitem)
-    failed = None
-    skipped = None
+
+    failure_cleanup = False
+    test_list = tests_passed
+    msg = 'OK'
+    msg_log = log.status_pass
     for report in reports:
         if report.outcome == 'failed':
-            failed = report
+            if hasattr(report, 'wasxfail'):
+                test_list = tests_xpassed
+                msg = 'XPASSED'
+                msg_log = log.status_xpass
+            else:
+                failure_cleanup = True
+                test_list = tests_failed
+                msg = 'FAILED:\n' + str(report.longrepr)
+                msg_log = log.status_fail
             break
         if report.outcome == 'skipped':
-            if not skipped:
-                skipped = report
-
-    if failed:
-        tests_failed.add(item.name)
-    elif skipped:
-        tests_skipped.add(item.name)
-    else:
-        tests_passed.add(item.name)
+            if hasattr(report, 'wasxfail'):
+                failure_cleanup = True
+                test_list = tests_xfailed
+                msg = 'XFAILED:\n' + str(report.longrepr)
+                msg_log = log.status_xfail
+                break
+            test_list = tests_skipped
+            msg = 'SKIPPED:\n' + str(report.longrepr)
+            msg_log = log.status_skipped
+
+    if failure_cleanup:
+        console.drain_console()
+
+    test_list.add(item.name)
     tests_not_run.remove(item.name)
 
     try:
-        if failed:
-            msg = 'FAILED:\n' + str(failed.longrepr)
-            log.status_fail(msg)
-        elif skipped:
-            msg = 'SKIPPED:\n' + str(skipped.longrepr)
-            log.status_skipped(msg)
-        else:
-            log.status_pass('OK')
+        msg_log(msg)
     except:
         # If something went wrong with logging, it's better to let the test
         # process continue, which may report other exceptions that triggered
@@ -416,7 +442,7 @@ def pytest_runtest_protocol(item, nextitem):
 
     log.end_section(item.name)
 
-    if failed:
+    if failure_cleanup:
         console.cleanup_spawn()
 
     return reports
diff --git a/test/py/multiplexed_log.css b/test/py/multiplexed_log.css
index 50f7b90..f6240d5 100644
--- a/test/py/multiplexed_log.css
+++ b/test/py/multiplexed_log.css
@@ -83,6 +83,14 @@ pre {
     color: #ffff00
 }
 
+.status-xfail {
+    color: #ff7f00
+}
+
+.status-xpass {
+    color: #ff7f00
+}
+
 .status-fail {
     color: #ff0000
 }
diff --git a/test/py/multiplexed_log.py b/test/py/multiplexed_log.py
index 48f2b51..69a577e 100644
--- a/test/py/multiplexed_log.py
+++ b/test/py/multiplexed_log.py
@@ -14,12 +14,12 @@ import subprocess
 mod_dir = os.path.dirname(os.path.abspath(__file__))
 
 class LogfileStream(object):
-    '''A file-like object used to write a single logical stream of data into
+    """A file-like object used to write a single logical stream of data into
     a multiplexed log file. Objects of this type should be created by factory
-    functions in the Logfile class rather than directly.'''
+    functions in the Logfile class rather than directly."""
 
     def __init__(self, logfile, name, chained_file):
-        '''Initialize a new object.
+        """Initialize a new object.
 
         Args:
             logfile: The Logfile object to log to.
@@ -29,26 +29,26 @@ class LogfileStream(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.logfile = logfile
         self.name = name
         self.chained_file = chained_file
 
     def close(self):
-        '''Dummy function so that this class is "file-like".
+        """Dummy function so that this class is "file-like".
 
         Args:
             None.
 
         Returns:
             Nothing.
-        '''
+        """
 
         pass
 
     def write(self, data, implicit=False):
-        '''Write data to the log stream.
+        """Write data to the log stream.
 
         Args:
             data: The data to write tot he file.
@@ -60,33 +60,33 @@ class LogfileStream(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.logfile.write(self, data, implicit)
         if self.chained_file:
             self.chained_file.write(data)
 
     def flush(self):
-        '''Flush the log stream, to ensure correct log interleaving.
+        """Flush the log stream, to ensure correct log interleaving.
 
         Args:
             None.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.logfile.flush()
         if self.chained_file:
             self.chained_file.flush()
 
 class RunAndLog(object):
-    '''A utility object used to execute sub-processes and log their output to
+    """A utility object used to execute sub-processes and log their output to
     a multiplexed log file. Objects of this type should be created by factory
-    functions in the Logfile class rather than directly.'''
+    functions in the Logfile class rather than directly."""
 
     def __init__(self, logfile, name, chained_file):
-        '''Initialize a new object.
+        """Initialize a new object.
 
         Args:
             logfile: The Logfile object to log to.
@@ -96,29 +96,33 @@ class RunAndLog(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.logfile = logfile
         self.name = name
         self.chained_file = chained_file
 
     def close(self):
-        '''Clean up any resources managed by this object.'''
+        """Clean up any resources managed by this object."""
         pass
 
-    def run(self, cmd, cwd=None):
-        '''Run a command as a sub-process, and log the results.
+    def run(self, cmd, cwd=None, ignore_errors=False):
+        """Run a command as a sub-process, and log the results.
 
         Args:
             cmd: The command to execute.
             cwd: The directory to run the command in. Can be None to use the
                 current directory.
+            ignore_errors: Indicate whether to ignore errors. If True, the
+                function will simply return if the command cannot be executed
+                or exits with an error code, otherwise an exception will be
+                raised if such problems occur.
 
         Returns:
             Nothing.
-        '''
+        """
 
-        msg = "+" + " ".join(cmd) + "\n"
+        msg = '+' + ' '.join(cmd) + '\n'
         if self.chained_file:
             self.chained_file.write(msg)
         self.logfile.write(self, msg)
@@ -148,7 +152,7 @@ class RunAndLog(object):
             exception = e
         if output and not output.endswith('\n'):
             output += '\n'
-        if exit_status and not exception:
+        if exit_status and not exception and not ignore_errors:
             exception = Exception('Exit code: ' + str(exit_status))
         if exception:
             output += str(exception) + '\n'
@@ -159,13 +163,13 @@ class RunAndLog(object):
             raise exception
 
 class SectionCtxMgr(object):
-    '''A context manager for Python's "with" statement, which allows a certain
+    """A context manager for Python's "with" statement, which allows a certain
     portion of test code to be logged to a separate section of the log file.
     Objects of this type should be created by factory functions in the Logfile
-    class rather than directly.'''
+    class rather than directly."""
 
     def __init__(self, log, marker):
-        '''Initialize a new object.
+        """Initialize a new object.
 
         Args:
             log: The Logfile object to log to.
@@ -173,7 +177,7 @@ class SectionCtxMgr(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.log = log
         self.marker = marker
@@ -185,35 +189,35 @@ class SectionCtxMgr(object):
         self.log.end_section(self.marker)
 
 class Logfile(object):
-    '''Generates an HTML-formatted log file containing multiple streams of
-    data, each represented in a well-delineated/-structured fashion.'''
+    """Generates an HTML-formatted log file containing multiple streams of
+    data, each represented in a well-delineated/-structured fashion."""
 
     def __init__(self, fn):
-        '''Initialize a new object.
+        """Initialize a new object.
 
         Args:
             fn: The filename to write to.
 
         Returns:
             Nothing.
-        '''
+        """
 
-        self.f = open(fn, "wt")
+        self.f = open(fn, 'wt')
         self.last_stream = None
         self.blocks = []
         self.cur_evt = 1
-        shutil.copy(mod_dir + "/multiplexed_log.css", os.path.dirname(fn))
-        self.f.write("""\
+        shutil.copy(mod_dir + '/multiplexed_log.css', os.path.dirname(fn))
+        self.f.write('''\
 <html>
 <head>
 <link rel="stylesheet" type="text/css" href="multiplexed_log.css">
 </head>
 <body>
 <tt>
-""")
+''')
 
     def close(self):
-        '''Close the log file.
+        """Close the log file.
 
         After calling this function, no more data may be written to the log.
 
@@ -222,22 +226,22 @@ class Logfile(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
-        self.f.write("""\
+        self.f.write('''\
 </tt>
 </body>
 </html>
-""")
+''')
         self.f.close()
 
     # The set of characters that should be represented as hexadecimal codes in
     # the log file.
-    _nonprint = ("%" + "".join(chr(c) for c in range(0, 32) if c not in (9, 10)) +
-                 "".join(chr(c) for c in range(127, 256)))
+    _nonprint = ('%' + ''.join(chr(c) for c in range(0, 32) if c not in (9, 10)) +
+                 ''.join(chr(c) for c in range(127, 256)))
 
     def _escape(self, data):
-        '''Render data format suitable for inclusion in an HTML document.
+        """Render data format suitable for inclusion in an HTML document.
 
         This includes HTML-escaping certain characters, and translating
         control characters to a hexadecimal representation.
@@ -247,36 +251,36 @@ class Logfile(object):
 
         Returns:
             An escaped version of the data.
-        '''
+        """
 
-        data = data.replace(chr(13), "")
-        data = "".join((c in self._nonprint) and ("%%%02x" % ord(c)) or
+        data = data.replace(chr(13), '')
+        data = ''.join((c in self._nonprint) and ('%%%02x' % ord(c)) or
                        c for c in data)
         data = cgi.escape(data)
         return data
 
     def _terminate_stream(self):
-        '''Write HTML to the log file to terminate the current stream's data.
+        """Write HTML to the log file to terminate the current stream's data.
 
         Args:
             None.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.cur_evt += 1
         if not self.last_stream:
             return
-        self.f.write("</pre>\n")
-        self.f.write("<div class=\"stream-trailer\" id=\"" +
-                     self.last_stream.name + "\">End stream: " +
-                     self.last_stream.name + "</div>\n")
-        self.f.write("</div>\n")
+        self.f.write('</pre>\n')
+        self.f.write('<div class="stream-trailer" id="' +
+                     self.last_stream.name + '">End stream: ' +
+                     self.last_stream.name + '</div>\n')
+        self.f.write('</div>\n')
         self.last_stream = None
 
     def _note(self, note_type, msg):
-        '''Write a note or one-off message to the log file.
+        """Write a note or one-off message to the log file.
 
         Args:
             note_type: The type of note. This must be a value supported by the
@@ -285,32 +289,32 @@ class Logfile(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._terminate_stream()
-        self.f.write("<div class=\"" + note_type + "\">\n<pre>")
+        self.f.write('<div class="' + note_type + '">\n<pre>')
         self.f.write(self._escape(msg))
-        self.f.write("\n</pre></div>\n")
+        self.f.write('\n</pre></div>\n')
 
     def start_section(self, marker):
-        '''Begin a new nested section in the log file.
+        """Begin a new nested section in the log file.
 
         Args:
             marker: The name of the section that is starting.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._terminate_stream()
         self.blocks.append(marker)
-        blk_path = "/".join(self.blocks)
-        self.f.write("<div class=\"section\" id=\"" + blk_path + "\">\n")
-        self.f.write("<div class=\"section-header\" id=\"" + blk_path +
-                     "\">Section: " + blk_path + "</div>\n")
+        blk_path = '/'.join(self.blocks)
+        self.f.write('<div class="section" id="' + blk_path + '">\n')
+        self.f.write('<div class="section-header" id="' + blk_path +
+                     '">Section: ' + blk_path + '</div>\n')
 
     def end_section(self, marker):
-        '''Terminate the current nested section in the log file.
+        """Terminate the current nested section in the log file.
 
         This function validates proper nesting of start_section() and
         end_section() calls. If a mismatch is found, an exception is raised.
@@ -320,20 +324,20 @@ class Logfile(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         if (not self.blocks) or (marker != self.blocks[-1]):
-            raise Exception("Block nesting mismatch: \"%s\" \"%s\"" %
-                            (marker, "/".join(self.blocks)))
+            raise Exception('Block nesting mismatch: "%s" "%s"' %
+                            (marker, '/'.join(self.blocks)))
         self._terminate_stream()
-        blk_path = "/".join(self.blocks)
-        self.f.write("<div class=\"section-trailer\" id=\"section-trailer-" +
-                     blk_path + "\">End section: " + blk_path + "</div>\n")
-        self.f.write("</div>\n")
+        blk_path = '/'.join(self.blocks)
+        self.f.write('<div class="section-trailer" id="section-trailer-' +
+                     blk_path + '">End section: ' + blk_path + '</div>\n')
+        self.f.write('</div>\n')
         self.blocks.pop()
 
     def section(self, marker):
-        '''Create a temporary section in the log file.
+        """Create a temporary section in the log file.
 
         This function creates a context manager for Python's "with" statement,
         which allows a certain portion of test code to be logged to a separate
@@ -348,96 +352,120 @@ class Logfile(object):
 
         Returns:
             A context manager object.
-        '''
+        """
 
         return SectionCtxMgr(self, marker)
 
     def error(self, msg):
-        '''Write an error note to the log file.
+        """Write an error note to the log file.
 
         Args:
             msg: A message describing the error.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("error", msg)
 
     def warning(self, msg):
-        '''Write an warning note to the log file.
+        """Write an warning note to the log file.
 
         Args:
             msg: A message describing the warning.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("warning", msg)
 
     def info(self, msg):
-        '''Write an informational note to the log file.
+        """Write an informational note to the log file.
 
         Args:
             msg: An informational message.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("info", msg)
 
     def action(self, msg):
-        '''Write an action note to the log file.
+        """Write an action note to the log file.
 
         Args:
             msg: A message describing the action that is being logged.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("action", msg)
 
     def status_pass(self, msg):
-        '''Write a note to the log file describing test(s) which passed.
+        """Write a note to the log file describing test(s) which passed.
 
         Args:
-            msg: A message describing passed test(s).
+            msg: A message describing the passed test(s).
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("status-pass", msg)
 
     def status_skipped(self, msg):
-        '''Write a note to the log file describing skipped test(s).
+        """Write a note to the log file describing skipped test(s).
 
         Args:
-            msg: A message describing passed test(s).
+            msg: A message describing the skipped test(s).
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("status-skipped", msg)
 
+    def status_xfail(self, msg):
+        """Write a note to the log file describing xfailed test(s).
+
+        Args:
+            msg: A message describing the xfailed test(s).
+
+        Returns:
+            Nothing.
+        """
+
+        self._note("status-xfail", msg)
+
+    def status_xpass(self, msg):
+        """Write a note to the log file describing xpassed test(s).
+
+        Args:
+            msg: A message describing the xpassed test(s).
+
+        Returns:
+            Nothing.
+        """
+
+        self._note("status-xpass", msg)
+
     def status_fail(self, msg):
-        '''Write a note to the log file describing failed test(s).
+        """Write a note to the log file describing failed test(s).
 
         Args:
-            msg: A message describing passed test(s).
+            msg: A message describing the failed test(s).
 
         Returns:
             Nothing.
-        '''
+        """
 
         self._note("status-fail", msg)
 
     def get_stream(self, name, chained_file=None):
-        '''Create an object to log a single stream's data into the log file.
+        """Create an object to log a single stream's data into the log file.
 
         This creates a "file-like" object that can be written to in order to
         write a single stream's data to the log file. The implementation will
@@ -452,12 +480,12 @@ class Logfile(object):
 
         Returns:
             A file-like object.
-        '''
+        """
 
         return LogfileStream(self, name, chained_file)
 
     def get_runner(self, name, chained_file=None):
-        '''Create an object that executes processes and logs their output.
+        """Create an object that executes processes and logs their output.
 
         Args:
             name: The name of this sub-process.
@@ -466,12 +494,12 @@ class Logfile(object):
 
         Returns:
             A RunAndLog object.
-        '''
+        """
 
         return RunAndLog(self, name, chained_file)
 
     def write(self, stream, data, implicit=False):
-        '''Write stream data into the log file.
+        """Write stream data into the log file.
 
         This function should only be used by instances of LogfileStream or
         RunAndLog.
@@ -487,29 +515,29 @@ class Logfile(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         if stream != self.last_stream:
             self._terminate_stream()
-            self.f.write("<div class=\"stream\" id=\"%s\">\n" % stream.name)
-            self.f.write("<div class=\"stream-header\" id=\"" + stream.name +
-                         "\">Stream: " + stream.name + "</div>\n")
-            self.f.write("<pre>")
+            self.f.write('<div class="stream" id="%s">\n' % stream.name)
+            self.f.write('<div class="stream-header" id="' + stream.name +
+                         '">Stream: ' + stream.name + '</div>\n')
+            self.f.write('<pre>')
         if implicit:
-            self.f.write("<span class=\"implicit\">")
+            self.f.write('<span class="implicit">')
         self.f.write(self._escape(data))
         if implicit:
-            self.f.write("</span>")
+            self.f.write('</span>')
         self.last_stream = stream
 
     def flush(self):
-        '''Flush the log stream, to ensure correct log interleaving.
+        """Flush the log stream, to ensure correct log interleaving.
 
         Args:
             None.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.f.flush()
diff --git a/test/py/test.py b/test/py/test.py
index 9c23898..95671d4 100755
--- a/test/py/test.py
+++ b/test/py/test.py
@@ -16,17 +16,17 @@ import sys
 sys.argv.pop(0)
 
 # argv; py.test test_directory_name user-supplied-arguments
-args = ["py.test", os.path.dirname(__file__) + "/tests"]
+args = ['py.test', os.path.dirname(__file__) + '/tests']
 args.extend(sys.argv)
 
 try:
-    os.execvp("py.test", args)
+    os.execvp('py.test', args)
 except:
     # Log full details of any exception for detailed analysis
     import traceback
     traceback.print_exc()
     # Hint to the user that they likely simply haven't installed the required
     # dependencies.
-    print >>sys.stderr, """
+    print >>sys.stderr, '''
 exec(py.test) failed; perhaps you are missing some dependencies?
-See test/py/README.md for the list."""
+See test/py/README.md for the list.'''
diff --git a/test/py/tests/test_000_version.py b/test/py/tests/test_000_version.py
index d262f05..43a02e7 100644
--- a/test/py/tests/test_000_version.py
+++ b/test/py/tests/test_000_version.py
@@ -9,7 +9,7 @@
 # command prompt.
 
 def test_version(u_boot_console):
-    '''Test that the "version" command prints the U-Boot version.'''
+    """Test that the "version" command prints the U-Boot version."""
 
     # "version" prints the U-Boot sign-on message. This is usually considered
     # an error, so that any unexpected reboot causes an error. Here, this
diff --git a/test/py/tests/test_dfu.py b/test/py/tests/test_dfu.py
new file mode 100644
index 0000000..093e8d0
--- /dev/null
+++ b/test/py/tests/test_dfu.py
@@ -0,0 +1,279 @@
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Test U-Boot's "dfu" command. The test starts DFU in U-Boot, waits for USB
+# device enumeration on the host, executes dfu-util multiple times to test
+# various transfer sizes, many of which trigger USB driver edge cases, and
+# finally aborts the "dfu" command in U-Boot.
+
+import os
+import os.path
+import pytest
+import u_boot_utils
+
+"""
+Note: This test relies on:
+
+a) boardenv_* to contain configuration values to define which USB ports are
+available for testing. Without this, this test will be automatically skipped.
+For example:
+
+env__usb_dev_ports = (
+    {
+        "fixture_id": "micro_b",
+        "tgt_usb_ctlr": "0",
+        "host_usb_dev_node": "/dev/usbdev-p2371-2180",
+        # This parameter is optional /if/ you only have a single board
+        # attached to your host at a time.
+        "host_usb_port_path": "3-13",
+    },
+)
+
+env__dfu_configs = (
+    # eMMC, partition 1
+    {
+        "fixture_id": "emmc",
+        "alt_info": "/dfu_test.bin ext4 0 1;/dfu_dummy.bin ext4 0 1",
+        "cmd_params": "mmc 0",
+        # This value is optional.
+        # If present, it specified the set of transfer sizes tested.
+        # If missing, a default list of sizes will be used, which covers
+        #   various useful corner cases.
+        # Manually specifying test sizes is useful if you wish to test 4 DFU
+        # configurations, but don't want to test every single transfer size
+        # on each, to avoid bloating the overall time taken by testing.
+        "test_sizes": (63, 64, 65),
+    },
+)
+
+b) udev rules to set permissions on devices nodes, so that sudo is not
+required. For example:
+
+ACTION=="add", SUBSYSTEM=="block", SUBSYSTEMS=="usb", KERNELS=="3-13", MODE:="666"
+
+(You may wish to change the group ID instead of setting the permissions wide
+open. All that matters is that the user ID running the test can access the
+device.)
+"""
+
+# The set of file sizes to test. These values trigger various edge-cases such
+# as one less than, equal to, and one greater than typical USB max packet
+# sizes, and similar boundary conditions.
+test_sizes_default = (
+    64 - 1,
+    64,
+    64 + 1,
+    128 - 1,
+    128,
+    128 + 1,
+    960 - 1,
+    960,
+    960 + 1,
+    4096 - 1,
+    4096,
+    4096 + 1,
+    1024 * 1024 - 1,
+    1024 * 1024,
+    8 * 1024 * 1024,
+)
+
+first_usb_dev_port = None
+
+@pytest.mark.buildconfigspec('cmd_dfu')
+def test_dfu(u_boot_console, env__usb_dev_port, env__dfu_config):
+    """Test the "dfu" command; the host system must be able to enumerate a USB
+    device when "dfu" is running, various DFU transfers are tested, and the
+    USB device must disappear when "dfu" is aborted.
+
+    Args:
+        u_boot_console: A U-Boot console connection.
+        env__usb_dev_port: The single USB device-mode port specification on
+            which to run the test. See the file-level comment above for
+            details of the format.
+        env__dfu_config: The single DFU (memory region) configuration on which
+            to run the test. See the file-level comment above for details
+            of the format.
+
+    Returns:
+        Nothing.
+    """
+
+    def start_dfu():
+        """Start U-Boot's dfu shell command.
+
+        This also waits for the host-side USB enumeration process to complete.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        """
+
+        fh = u_boot_utils.attempt_to_open_file(
+            env__usb_dev_port['host_usb_dev_node'])
+        if fh:
+            fh.close()
+            raise Exception('USB device present before dfu command invoked')
+
+        u_boot_console.log.action(
+            'Starting long-running U-Boot dfu shell command')
+
+        cmd = 'setenv dfu_alt_info "%s"' % env__dfu_config['alt_info']
+        u_boot_console.run_command(cmd)
+
+        cmd = 'dfu 0 ' + env__dfu_config['cmd_params']
+        u_boot_console.run_command(cmd, wait_for_prompt=False)
+        u_boot_console.log.action('Waiting for DFU USB device to appear')
+        fh = u_boot_utils.wait_until_open_succeeds(
+            env__usb_dev_port['host_usb_dev_node'])
+        fh.close()
+
+    def stop_dfu(ignore_errors):
+        """Stop U-Boot's dfu shell command from executing.
+
+        This also waits for the host-side USB de-enumeration process to
+        complete.
+
+        Args:
+            ignore_errors: Ignore any errors. This is useful if an error has
+                already been detected, and the code is performing best-effort
+                cleanup. In this case, we do not want to mask the original
+                error by "honoring" any new errors.
+
+        Returns:
+            Nothing.
+        """
+
+        try:
+            u_boot_console.log.action(
+                'Stopping long-running U-Boot dfu shell command')
+            u_boot_console.ctrlc()
+            u_boot_console.log.action(
+                'Waiting for DFU USB device to disappear')
+            u_boot_utils.wait_until_file_open_fails(
+                env__usb_dev_port['host_usb_dev_node'], ignore_errors)
+        except:
+            if not ignore_errors:
+                raise
+
+    def run_dfu_util(alt_setting, fn, up_dn_load_arg):
+        """Invoke dfu-util on the host.
+
+        Args:
+            alt_setting: The DFU "alternate setting" identifier to interact
+                with.
+            fn: The host-side file name to transfer.
+            up_dn_load_arg: '-U' or '-D' depending on whether a DFU upload or
+                download operation should be performed.
+
+        Returns:
+            Nothing.
+        """
+
+        cmd = ['dfu-util', '-a', str(alt_setting), up_dn_load_arg, fn]
+        if 'host_usb_port_path' in env__usb_dev_port:
+            cmd += ['-p', env__usb_dev_port['host_usb_port_path']]
+        u_boot_utils.run_and_log(u_boot_console, cmd)
+        u_boot_console.wait_for('Ctrl+C to exit ...')
+
+    def dfu_write(alt_setting, fn):
+        """Write a file to the target board using DFU.
+
+        Args:
+            alt_setting: The DFU "alternate setting" identifier to interact
+                with.
+            fn: The host-side file name to transfer.
+
+        Returns:
+            Nothing.
+        """
+
+        run_dfu_util(alt_setting, fn, '-D')
+
+    def dfu_read(alt_setting, fn):
+        """Read a file from the target board using DFU.
+
+        Args:
+            alt_setting: The DFU "alternate setting" identifier to interact
+                with.
+            fn: The host-side file name to transfer.
+
+        Returns:
+            Nothing.
+        """
+
+        # dfu-util fails reads/uploads if the host file already exists
+        if os.path.exists(fn):
+            os.remove(fn)
+        run_dfu_util(alt_setting, fn, '-U')
+
+    def dfu_write_read_check(size):
+        """Test DFU transfers of a specific size of data
+
+        This function first writes data to the board then reads it back and
+        compares the written and read back data. Measures are taken to avoid
+        certain types of false positives.
+
+        Args:
+            size: The data size to test.
+
+        Returns:
+            Nothing.
+        """
+
+        test_f = u_boot_utils.PersistentRandomFile(u_boot_console,
+            'dfu_%d.bin' % size, size)
+        readback_fn = u_boot_console.config.result_dir + '/dfu_readback.bin'
+
+        u_boot_console.log.action('Writing test data to DFU primary ' +
+            'altsetting')
+        dfu_write(0, test_f.abs_fn)
+
+        u_boot_console.log.action('Writing dummy data to DFU secondary ' +
+            'altsetting to clear DFU buffers')
+        dfu_write(1, dummy_f.abs_fn)
+
+        u_boot_console.log.action('Reading DFU primary altsetting for ' +
+            'comparison')
+        dfu_read(0, readback_fn)
+
+        u_boot_console.log.action('Comparing written and read data')
+        written_hash = test_f.content_hash
+        read_back_hash = u_boot_utils.md5sum_file(readback_fn, size)
+        assert(written_hash == read_back_hash)
+
+    # This test may be executed against multiple USB ports. The test takes a
+    # long time, so we don't want to do the whole thing each time. Instead,
+    # execute the full test on the first USB port, and perform a very limited
+    # test on other ports. In the limited case, we solely validate that the
+    # host PC can enumerate the U-Boot USB device.
+    global first_usb_dev_port
+    if not first_usb_dev_port:
+        first_usb_dev_port = env__usb_dev_port
+    if env__usb_dev_port == first_usb_dev_port:
+        sizes = env__dfu_config.get('test_sizes', test_sizes_default)
+    else:
+        sizes = []
+
+    dummy_f = u_boot_utils.PersistentRandomFile(u_boot_console,
+        'dfu_dummy.bin', 1024)
+
+    ignore_cleanup_errors = True
+    try:
+        start_dfu()
+
+        u_boot_console.log.action(
+            'Overwriting DFU primary altsetting with dummy data')
+        dfu_write(0, dummy_f.abs_fn)
+
+        for size in sizes:
+            with u_boot_console.log.section('Data size %d' % size):
+                dfu_write_read_check(size)
+                # Make the status of each sub-test obvious. If the test didn't
+                # pass, an exception was thrown so this code isn't executed.
+                u_boot_console.log.status_pass('OK')
+        ignore_cleanup_errors = False
+    finally:
+        stop_dfu(ignore_cleanup_errors)
diff --git a/test/py/tests/test_env.py b/test/py/tests/test_env.py
index a3e8dd3..c41aa5a 100644
--- a/test/py/tests/test_env.py
+++ b/test/py/tests/test_env.py
@@ -10,34 +10,34 @@ import pytest
 # FIXME: This might be useful for other tests;
 # perhaps refactor it into ConsoleBase or some other state object?
 class StateTestEnv(object):
-    '''Container that represents the state of all U-Boot environment variables.
+    """Container that represents the state of all U-Boot environment variables.
     This enables quick determination of existant/non-existant variable
     names.
-    '''
+    """
 
     def __init__(self, u_boot_console):
-        '''Initialize a new StateTestEnv object.
+        """Initialize a new StateTestEnv object.
 
         Args:
             u_boot_console: A U-Boot console.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.u_boot_console = u_boot_console
         self.get_env()
         self.set_var = self.get_non_existent_var()
 
     def get_env(self):
-        '''Read all current environment variables from U-Boot.
+        """Read all current environment variables from U-Boot.
 
         Args:
             None.
 
         Returns:
             Nothing.
-        '''
+        """
 
         response = self.u_boot_console.run_command('printenv')
         self.env = {}
@@ -48,27 +48,27 @@ class StateTestEnv(object):
             self.env[var] = value
 
     def get_existent_var(self):
-        '''Return the name of an environment variable that exists.
+        """Return the name of an environment variable that exists.
 
         Args:
             None.
 
         Returns:
             The name of an environment variable.
-        '''
+        """
 
         for var in self.env:
             return var
 
     def get_non_existent_var(self):
-        '''Return the name of an environment variable that does not exist.
+        """Return the name of an environment variable that does not exist.
 
         Args:
             None.
 
         Returns:
             The name of an environment variable.
-        '''
+        """
 
         n = 0
         while True:
@@ -77,63 +77,67 @@ class StateTestEnv(object):
                 return var
             n += 1
 
-@pytest.fixture(scope='module')
+ste = None
+@pytest.fixture(scope='function')
 def state_test_env(u_boot_console):
-    '''pytest fixture to provide a StateTestEnv object to tests.'''
+    """pytest fixture to provide a StateTestEnv object to tests."""
 
-    return StateTestEnv(u_boot_console)
+    global ste
+    if not ste:
+        ste = StateTestEnv(u_boot_console)
+    return ste
 
 def unset_var(state_test_env, var):
-    '''Unset an environment variable.
+    """Unset an environment variable.
 
     This both executes a U-Boot shell command and updates a StateTestEnv
     object.
 
     Args:
-        state_test_env: The StateTestEnv object to updata.
+        state_test_env: The StateTestEnv object to update.
         var: The variable name to unset.
 
     Returns:
         Nothing.
-    '''
+    """
 
     state_test_env.u_boot_console.run_command('setenv %s' % var)
     if var in state_test_env.env:
         del state_test_env.env[var]
 
 def set_var(state_test_env, var, value):
-    '''Set an environment variable.
+    """Set an environment variable.
 
     This both executes a U-Boot shell command and updates a StateTestEnv
     object.
 
     Args:
-        state_test_env: The StateTestEnv object to updata.
+        state_test_env: The StateTestEnv object to update.
         var: The variable name to set.
         value: The value to set the variable to.
 
     Returns:
         Nothing.
-    '''
+    """
 
     state_test_env.u_boot_console.run_command('setenv %s "%s"' % (var, value))
     state_test_env.env[var] = value
 
 def validate_empty(state_test_env, var):
-    '''Validate that a variable is not set, using U-Boot shell commands.
+    """Validate that a variable is not set, using U-Boot shell commands.
 
     Args:
         var: The variable name to test.
 
     Returns:
         Nothing.
-    '''
+    """
 
     response = state_test_env.u_boot_console.run_command('echo $%s' % var)
     assert response == ''
 
 def validate_set(state_test_env, var, value):
-    '''Validate that a variable is set, using U-Boot shell commands.
+    """Validate that a variable is set, using U-Boot shell commands.
 
     Args:
         var: The variable name to test.
@@ -141,7 +145,7 @@ def validate_set(state_test_env, var, value):
 
     Returns:
         Nothing.
-    '''
+    """
 
     # echo does not preserve leading, internal, or trailing whitespace in the
     # value. printenv does, and hence allows more complete testing.
@@ -149,20 +153,20 @@ def validate_set(state_test_env, var, value):
     assert response == ('%s=%s' % (var, value))
 
 def test_env_echo_exists(state_test_env):
-    '''Test echoing a variable that exists.'''
+    """Test echoing a variable that exists."""
 
     var = state_test_env.get_existent_var()
     value = state_test_env.env[var]
     validate_set(state_test_env, var, value)
 
 def test_env_echo_non_existent(state_test_env):
-    '''Test echoing a variable that doesn't exist.'''
+    """Test echoing a variable that doesn't exist."""
 
     var = state_test_env.set_var
     validate_empty(state_test_env, var)
 
 def test_env_printenv_non_existent(state_test_env):
-    '''Test printenv error message for non-existant variables.'''
+    """Test printenv error message for non-existant variables."""
 
     var = state_test_env.set_var
     c = state_test_env.u_boot_console
@@ -171,14 +175,14 @@ def test_env_printenv_non_existent(state_test_env):
     assert(response == '## Error: "%s" not defined' % var)
 
 def test_env_unset_non_existent(state_test_env):
-    '''Test unsetting a nonexistent variable.'''
+    """Test unsetting a nonexistent variable."""
 
     var = state_test_env.get_non_existent_var()
     unset_var(state_test_env, var)
     validate_empty(state_test_env, var)
 
 def test_env_set_non_existent(state_test_env):
-    '''Test set a non-existant variable.'''
+    """Test set a non-existant variable."""
 
     var = state_test_env.set_var
     value = 'foo'
@@ -186,7 +190,7 @@ def test_env_set_non_existent(state_test_env):
     validate_set(state_test_env, var, value)
 
 def test_env_set_existing(state_test_env):
-    '''Test setting an existant variable.'''
+    """Test setting an existant variable."""
 
     var = state_test_env.set_var
     value = 'bar'
@@ -194,14 +198,14 @@ def test_env_set_existing(state_test_env):
     validate_set(state_test_env, var, value)
 
 def test_env_unset_existing(state_test_env):
-    '''Test unsetting a variable.'''
+    """Test unsetting a variable."""
 
     var = state_test_env.set_var
     unset_var(state_test_env, var)
     validate_empty(state_test_env, var)
 
 def test_env_expansion_spaces(state_test_env):
-    '''Test expanding a variable that contains a space in its value.'''
+    """Test expanding a variable that contains a space in its value."""
 
     var_space = None
     var_test = None
diff --git a/test/py/tests/test_help.py b/test/py/tests/test_help.py
index 894f3b5..420090c 100644
--- a/test/py/tests/test_help.py
+++ b/test/py/tests/test_help.py
@@ -4,6 +4,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
 def test_help(u_boot_console):
-    '''Test that the "help" command can be executed.'''
+    """Test that the "help" command can be executed."""
 
     u_boot_console.run_command('help')
diff --git a/test/py/tests/test_hush_if_test.py b/test/py/tests/test_hush_if_test.py
index cf4c3ae..8b88425 100644
--- a/test/py/tests/test_hush_if_test.py
+++ b/test/py/tests/test_hush_if_test.py
@@ -95,7 +95,7 @@ subtests = (
 )
 
 def exec_hush_if(u_boot_console, expr, result):
-    '''Execute a shell "if" command, and validate its result.'''
+    """Execute a shell "if" command, and validate its result."""
 
     cmd = 'if ' + expr + '; then echo true; else echo false; fi'
     response = u_boot_console.run_command(cmd)
@@ -103,7 +103,7 @@ def exec_hush_if(u_boot_console, expr, result):
 
 @pytest.mark.buildconfigspec('sys_hush_parser')
 def test_hush_if_test_setup(u_boot_console):
-    '''Set up environment variables used during the "if" tests.'''
+    """Set up environment variables used during the "if" tests."""
 
     u_boot_console.run_command('setenv ut_var_nonexistent')
     u_boot_console.run_command('setenv ut_var_exists 1')
@@ -111,13 +111,13 @@ def test_hush_if_test_setup(u_boot_console):
 @pytest.mark.buildconfigspec('sys_hush_parser')
 @pytest.mark.parametrize('expr,result', subtests)
 def test_hush_if_test(u_boot_console, expr, result):
-    '''Test a single "if test" condition.'''
+    """Test a single "if test" condition."""
 
     exec_hush_if(u_boot_console, expr, result)
 
 @pytest.mark.buildconfigspec('sys_hush_parser')
 def test_hush_if_test_teardown(u_boot_console):
-    '''Clean up environment variables used during the "if" tests.'''
+    """Clean up environment variables used during the "if" tests."""
 
     u_boot_console.run_command('setenv ut_var_exists')
 
@@ -126,7 +126,7 @@ def test_hush_if_test_teardown(u_boot_console):
 # Of those, only UMS currently allows file removal though.
 @pytest.mark.boardspec('sandbox')
 def test_hush_if_test_host_file_exists(u_boot_console):
-    '''Test the "if test -e" shell command.'''
+    """Test the "if test -e" shell command."""
 
     test_file = u_boot_console.config.result_dir + \
         '/creating_this_file_breaks_u_boot_tests'
diff --git a/test/py/tests/test_md.py b/test/py/tests/test_md.py
index 94603c7..5fe2582 100644
--- a/test/py/tests/test_md.py
+++ b/test/py/tests/test_md.py
@@ -4,13 +4,14 @@
 # SPDX-License-Identifier: GPL-2.0
 
 import pytest
+import u_boot_utils
 
 @pytest.mark.buildconfigspec('cmd_memory')
 def test_md(u_boot_console):
-    '''Test that md reads memory as expected, and that memory can be modified
-    using the mw command.'''
+    """Test that md reads memory as expected, and that memory can be modified
+    using the mw command."""
 
-    ram_base = u_boot_console.find_ram_base()
+    ram_base = u_boot_utils.find_ram_base(u_boot_console)
     addr = '%08x' % ram_base
     val = 'a5f09876'
     expected_response = addr + ': ' + val
@@ -23,10 +24,10 @@ def test_md(u_boot_console):
 
 @pytest.mark.buildconfigspec('cmd_memory')
 def test_md_repeat(u_boot_console):
-    '''Test command repeat (via executing an empty command) operates correctly
-    for "md"; the command must repeat and dump an incrementing address.'''
+    """Test command repeat (via executing an empty command) operates correctly
+    for "md"; the command must repeat and dump an incrementing address."""
 
-    ram_base = u_boot_console.find_ram_base()
+    ram_base = u_boot_utils.find_ram_base(u_boot_console)
     addr_base = '%08x' % ram_base
     words = 0x10
     addr_repeat = '%08x' % (ram_base + (words * 4))
diff --git a/test/py/tests/test_net.py b/test/py/tests/test_net.py
new file mode 100644
index 0000000..07393eb
--- /dev/null
+++ b/test/py/tests/test_net.py
@@ -0,0 +1,155 @@
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Test various network-related functionality, such as the dhcp, ping, and
+# tftpboot commands.
+
+import pytest
+import u_boot_utils
+
+"""
+Note: This test relies on boardenv_* containing configuration values to define
+which the network environment available for testing. Without this, this test
+will be automatically skipped.
+
+For example:
+
+# Boolean indicating whether the Ethernet device is attached to USB, and hence
+# USB enumeration needs to be performed prior to network tests.
+# This variable may be omitted if its value is False.
+env__net_uses_usb = False
+
+# Boolean indicating whether the Ethernet device is attached to PCI, and hence
+# PCI enumeration needs to be performed prior to network tests.
+# This variable may be omitted if its value is False.
+env__net_uses_pci = True
+
+# True if a DHCP server is attached to the network, and should be tested.
+# If DHCP testing is not possible or desired, this variable may be omitted or
+# set to False.
+env__net_dhcp_server = True
+
+# A list of environment variables that should be set in order to configure a
+# static IP. If solely relying on DHCP, this variable may be omitted or set to
+# an empty list.
+env__net_static_env_vars = [
+    ("ipaddr", "10.0.0.100"),
+    ("netmask", "255.255.255.0"),
+    ("serverip", "10.0.0.1"),
+]
+
+# Details regarding a file that may be read from a TFTP server. This variable
+# may be omitted or set to None if TFTP testing is not possible or desired.
+env__net_tftp_readable_file = {
+    "fn": "ubtest-readable.bin",
+    "size": 5058624,
+    "crc32": "c2244b26",
+}
+"""
+
+net_set_up = False
+
+def test_net_pre_commands(u_boot_console):
+    """Execute any commands required to enable network hardware.
+
+    These commands are provided by the boardenv_* file; see the comment at the
+    beginning of this file.
+    """
+
+    init_usb = u_boot_console.config.env.get('env__net_uses_usb', False)
+    if init_usb:
+        u_boot_console.run_command('usb start')
+
+    init_pci = u_boot_console.config.env.get('env__net_uses_pci', False)
+    if init_pci:
+        u_boot_console.run_command('pci enum')
+
+@pytest.mark.buildconfigspec('cmd_dhcp')
+def test_net_dhcp(u_boot_console):
+    """Test the dhcp command.
+
+    The boardenv_* file may be used to enable/disable this test; see the
+    comment at the beginning of this file.
+    """
+
+    test_dhcp = u_boot_console.config.env.get('env__net_dhcp_server', False)
+    if not test_dhcp:
+        pytest.skip('No DHCP server available')
+
+    u_boot_console.run_command('setenv autoload no')
+    output = u_boot_console.run_command('dhcp')
+    assert 'DHCP client bound to address ' in output
+
+    global net_set_up
+    net_set_up = True
+
+@pytest.mark.buildconfigspec('net')
+def test_net_setup_static(u_boot_console):
+    """Set up a static IP configuration.
+
+    The configuration is provided by the boardenv_* file; see the comment at
+    the beginning of this file.
+    """
+
+    env_vars = u_boot_console.config.env.get('env__net_static_env_vars', None)
+    if not env_vars:
+        pytest.skip('No static network configuration is defined')
+
+    for (var, val) in env_vars:
+        u_boot_console.run_command('setenv %s %s' % (var, val))
+
+    global net_set_up
+    net_set_up = True
+
+@pytest.mark.buildconfigspec('cmd_ping')
+def test_net_ping(u_boot_console):
+    """Test the ping command.
+
+    The $serverip (as set up by either test_net_dhcp or test_net_setup_static)
+    is pinged. The test validates that the host is alive, as reported by the
+    ping command's output.
+    """
+
+    if not net_set_up:
+        pytest.skip('Network not initialized')
+
+    output = u_boot_console.run_command('ping $serverip')
+    assert 'is alive' in output
+
+@pytest.mark.buildconfigspec('cmd_net')
+def test_net_tftpboot(u_boot_console):
+    """Test the tftpboot command.
+
+    A file is downloaded from the TFTP server, its size and optionally its
+    CRC32 are validated.
+
+    The details of the file to download are provided by the boardenv_* file;
+    see the comment at the beginning of this file.
+    """
+
+    if not net_set_up:
+        pytest.skip('Network not initialized')
+
+    f = u_boot_console.config.env.get('env__net_tftp_readable_file', None)
+    if not f:
+        pytest.skip('No TFTP readable file to read')
+
+    addr = u_boot_utils.find_ram_base(u_boot_console)
+    fn = f['fn']
+    output = u_boot_console.run_command('tftpboot %x %s' % (addr, fn))
+    expected_text = 'Bytes transferred = '
+    sz = f.get('size', None)
+    if sz:
+        expected_text += '%d' % sz
+    assert expected_text in output
+
+    expected_crc = f.get('crc32', None)
+    if not expected_crc:
+        return
+
+    if u_boot_console.config.buildconfig.get('config_cmd_crc32', 'n') != 'y':
+        return
+
+    output = u_boot_console.run_command('crc32 %x $filesize' % addr)
+    assert expected_crc in output
diff --git a/test/py/tests/test_sandbox_exit.py b/test/py/tests/test_sandbox_exit.py
index 2aa8eb4..d1aa308 100644
--- a/test/py/tests/test_sandbox_exit.py
+++ b/test/py/tests/test_sandbox_exit.py
@@ -9,16 +9,14 @@ import signal
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('reset')
 def test_reset(u_boot_console):
-    '''Test that the "reset" command exits sandbox process.'''
+    """Test that the "reset" command exits sandbox process."""
 
     u_boot_console.run_command('reset', wait_for_prompt=False)
     assert(u_boot_console.validate_exited())
-    u_boot_console.ensure_spawned()
 
 @pytest.mark.boardspec('sandbox')
 def test_ctrl_c(u_boot_console):
-    '''Test that sending SIGINT to sandbox causes it to exit.'''
+    """Test that sending SIGINT to sandbox causes it to exit."""
 
     u_boot_console.kill(signal.SIGINT)
     assert(u_boot_console.validate_exited())
-    u_boot_console.ensure_spawned()
diff --git a/test/py/tests/test_shell_basics.py b/test/py/tests/test_shell_basics.py
index 719ce61..702e5e2 100644
--- a/test/py/tests/test_shell_basics.py
+++ b/test/py/tests/test_shell_basics.py
@@ -5,13 +5,13 @@
 # Test basic shell functionality, such as commands separate by semi-colons.
 
 def test_shell_execute(u_boot_console):
-    '''Test any shell command.'''
+    """Test any shell command."""
 
     response = u_boot_console.run_command('echo hello')
     assert response.strip() == 'hello'
 
 def test_shell_semicolon_two(u_boot_console):
-    '''Test two shell commands separate by a semi-colon.'''
+    """Test two shell commands separate by a semi-colon."""
 
     cmd = 'echo hello; echo world'
     response = u_boot_console.run_command(cmd)
@@ -19,8 +19,8 @@ def test_shell_semicolon_two(u_boot_console):
     assert response.index('hello') < response.index('world')
 
 def test_shell_semicolon_three(u_boot_console):
-    '''Test three shell commands separate by a semi-colon, with variable
-    expansion dependencies between them.'''
+    """Test three shell commands separate by a semi-colon, with variable
+    expansion dependencies between them."""
 
     cmd = 'setenv list 1; setenv list ${list}2; setenv list ${list}3; ' + \
         'echo ${list}'
@@ -29,9 +29,9 @@ def test_shell_semicolon_three(u_boot_console):
     u_boot_console.run_command('setenv list')
 
 def test_shell_run(u_boot_console):
-    '''Test the "run" shell command.'''
+    """Test the "run" shell command."""
 
-    u_boot_console.run_command('setenv foo \"setenv monty 1; setenv python 2\"')
+    u_boot_console.run_command('setenv foo "setenv monty 1; setenv python 2"')
     u_boot_console.run_command('run foo')
     response = u_boot_console.run_command('echo $monty')
     assert response.strip() == '1'
diff --git a/test/py/tests/test_sleep.py b/test/py/tests/test_sleep.py
index 64f1ddf..74add89 100644
--- a/test/py/tests/test_sleep.py
+++ b/test/py/tests/test_sleep.py
@@ -6,12 +6,8 @@ import pytest
 import time
 
 def test_sleep(u_boot_console):
-    '''Test the sleep command, and validate that it sleeps for approximately
-    the correct amount of time.'''
-
-    # Do this before we time anything, to make sure U-Boot is already running.
-    # Otherwise, the system boot time is included in the time measurement.
-    u_boot_console.ensure_spawned()
+    """Test the sleep command, and validate that it sleeps for approximately
+    the correct amount of time."""
 
     # 3s isn't too long, but is enough to cross a few second boundaries.
     sleep_time = 3
diff --git a/test/py/tests/test_ums.py b/test/py/tests/test_ums.py
index a137221..8c3ee2b 100644
--- a/test/py/tests/test_ums.py
+++ b/test/py/tests/test_ums.py
@@ -2,28 +2,58 @@
 #
 # SPDX-License-Identifier: GPL-2.0
 
-# Test U-Boot's "ums" command. At present, this test only ensures that a UMS
-# device can be enumerated by the host/test machine. In the future, this test
-# should be enhanced to validate disk IO.
+# Test U-Boot's "ums" command. The test starts UMS in U-Boot, waits for USB
+# device enumeration on the host, reads a small block of data from the UMS
+# block device, optionally mounts a partition and performs filesystem-based
+# read/write tests, and finally aborts the "ums" command in U-Boot.
 
 import os
+import os.path
 import pytest
+import re
 import time
+import u_boot_utils
 
-'''
+"""
 Note: This test relies on:
 
 a) boardenv_* to contain configuration values to define which USB ports are
 available for testing. Without this, this test will be automatically skipped.
 For example:
 
+# Leave this list empty if you have no block_devs below with writable
+# partitions defined.
+env__mount_points = (
+    "/mnt/ubtest-mnt-p2371-2180-na",
+)
+
 env__usb_dev_ports = (
-    {'tgt_usb_ctlr': '0', 'host_ums_dev_node': '/dev/disk/by-path/pci-0000:00:14.0-usb-0:13:1.0-scsi-0:0:0:0'},
+    {
+        "fixture_id": "micro_b",
+        "tgt_usb_ctlr": "0",
+        "host_ums_dev_node": "/dev/disk/by-path/pci-0000:00:14.0-usb-0:13:1.0-scsi-0:0:0:0",
+    },
 )
 
 env__block_devs = (
-    {'type': 'mmc', 'id': '0'}, # eMMC; always present
-    {'type': 'mmc', 'id': '1'}, # SD card; present since I plugged one in
+    # eMMC; always present
+    {
+        "fixture_id": "emmc",
+        "type": "mmc",
+        "id": "0",
+        # The following two properties are optional.
+        # If present, the partition will be mounted and a file written-to and
+        # read-from it. If missing, only a simple block read test will be
+        # performed.
+        "writable_fs_partition": 1,
+        "writable_fs_subdir": "tmp/",
+    },
+    # SD card; present since I plugged one in
+    {
+        "fixture_id": "sd",
+        "type": "mmc",
+        "id": "1"
+    },
 )
 
 b) udev rules to set permissions on devices nodes, so that sudo is not
@@ -34,47 +64,42 @@ ACTION=="add", SUBSYSTEM=="block", SUBSYSTEMS=="usb", KERNELS=="3-13", MODE:="66
 (You may wish to change the group ID instead of setting the permissions wide
 open. All that matters is that the user ID running the test can access the
 device.)
-'''
 
-def open_ums_device(host_ums_dev_node):
-    '''Attempt to open a device node, returning either the opened file handle,
-    or None on any error.'''
+c) /etc/fstab entries to allow the block device to be mounted without requiring
+root permissions. For example:
 
-    try:
-        return open(host_ums_dev_node, 'rb')
-    except:
-        return None
-
-def wait_for_ums_device(host_ums_dev_node):
-    '''Continually attempt to open the device node exported by the "ums"
-    command, and either return the opened file handle, or raise an exception
-    after a timeout.'''
-
-    for i in xrange(100):
-        fh = open_ums_device(host_ums_dev_node)
-        if fh:
-            return fh
-        time.sleep(0.1)
-    raise Exception('UMS device did not appear')
-
-def wait_for_ums_device_gone(host_ums_dev_node):
-    '''Continually attempt to open the device node exported by the "ums"
-    command, and either return once the device has disappeared, or raise an
-    exception if it does not before a timeout occurs.'''
-
-    for i in xrange(100):
-        fh = open_ums_device(host_ums_dev_node)
-        if not fh:
-            return
-        fh.close()
-        time.sleep(0.1)
-    raise Exception('UMS device did not disappear')
+/dev/disk/by-path/pci-0000:00:14.0-usb-0:13:1.0-scsi-0:0:0:0-part1 /mnt/ubtest-mnt-p2371-2180-na ext4 noauto,user,nosuid,nodev
+
+This entry is only needed if any block_devs above contain a
+writable_fs_partition value.
+"""
 
 @pytest.mark.buildconfigspec('cmd_usb_mass_storage')
 def test_ums(u_boot_console, env__usb_dev_port, env__block_devs):
-    '''Test the "ums" command; the host system must be able to enumerate a UMS
-    device when "ums" is running, and this device must disappear when "ums" is
-    aborted.'''
+    """Test the "ums" command; the host system must be able to enumerate a UMS
+    device when "ums" is running, block and optionally file I/O are tested,
+    and this device must disappear when "ums" is aborted.
+
+    Args:
+        u_boot_console: A U-Boot console connection.
+        env__usb_dev_port: The single USB device-mode port specification on
+            which to run the test. See the file-level comment above for
+            details of the format.
+        env__block_devs: The list of block devices that the target U-Boot
+            device has attached. See the file-level comment above for details
+            of the format.
+
+    Returns:
+        Nothing.
+    """
+
+    have_writable_fs_partition = 'writable_fs_partition' in env__block_devs[0]
+    if not have_writable_fs_partition:
+        # If 'writable_fs_subdir' is missing, we'll skip all parts of the
+        # testing which mount filesystems.
+        u_boot_console.log.warning(
+            'boardenv missing "writable_fs_partition"; ' +
+            'UMS testing will be limited.')
 
     tgt_usb_ctlr = env__usb_dev_port['tgt_usb_ctlr']
     host_ums_dev_node = env__usb_dev_port['host_ums_dev_node']
@@ -84,11 +109,129 @@ def test_ums(u_boot_console, env__usb_dev_port, env__block_devs):
     # device list here. We'll test each block device somewhere else.
     tgt_dev_type = env__block_devs[0]['type']
     tgt_dev_id = env__block_devs[0]['id']
+    if have_writable_fs_partition:
+        mount_point = u_boot_console.config.env['env__mount_points'][0]
+        mount_subdir = env__block_devs[0]['writable_fs_subdir']
+        part_num = env__block_devs[0]['writable_fs_partition']
+        host_ums_part_node = '%s-part%d' % (host_ums_dev_node, part_num)
+    else:
+        host_ums_part_node = host_ums_dev_node
+
+    test_f = u_boot_utils.PersistentRandomFile(u_boot_console, 'ums.bin',
+        1024 * 1024);
+    if have_writable_fs_partition:
+        mounted_test_fn = mount_point + '/' + mount_subdir + test_f.fn
+
+    def start_ums():
+        """Start U-Boot's ums shell command.
+
+        This also waits for the host-side USB enumeration process to complete.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        """
+
+        u_boot_console.log.action(
+            'Starting long-running U-Boot ums shell command')
+        cmd = 'ums %s %s %s' % (tgt_usb_ctlr, tgt_dev_type, tgt_dev_id)
+        u_boot_console.run_command(cmd, wait_for_prompt=False)
+        u_boot_console.wait_for(re.compile('UMS: LUN.*[\r\n]'))
+        fh = u_boot_utils.wait_until_open_succeeds(host_ums_part_node)
+        u_boot_console.log.action('Reading raw data from UMS device')
+        fh.read(4096)
+        fh.close()
+
+    def mount():
+        """Mount the block device that U-Boot exports.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        """
+
+        u_boot_console.log.action('Mounting exported UMS device')
+        cmd = ('/bin/mount', host_ums_part_node)
+        u_boot_utils.run_and_log(u_boot_console, cmd)
+
+    def umount(ignore_errors):
+        """Unmount the block device that U-Boot exports.
 
-    cmd = 'ums %s %s %s' % (tgt_usb_ctlr, tgt_dev_type, tgt_dev_id)
-    u_boot_console.run_command('ums 0 mmc 0', wait_for_prompt=False)
-    fh = wait_for_ums_device(host_ums_dev_node)
-    fh.read(4096)
-    fh.close()
-    u_boot_console.ctrlc()
-    wait_for_ums_device_gone(host_ums_dev_node)
+        Args:
+            ignore_errors: Ignore any errors. This is useful if an error has
+                already been detected, and the code is performing best-effort
+                cleanup. In this case, we do not want to mask the original
+                error by "honoring" any new errors.
+
+        Returns:
+            Nothing.
+        """
+
+        u_boot_console.log.action('Unmounting UMS device')
+        cmd = ('/bin/umount', host_ums_part_node)
+        u_boot_utils.run_and_log(u_boot_console, cmd, ignore_errors)
+
+    def stop_ums(ignore_errors):
+        """Stop U-Boot's ums shell command from executing.
+
+        This also waits for the host-side USB de-enumeration process to
+        complete.
+
+        Args:
+            ignore_errors: Ignore any errors. This is useful if an error has
+                already been detected, and the code is performing best-effort
+                cleanup. In this case, we do not want to mask the original
+                error by "honoring" any new errors.
+
+        Returns:
+            Nothing.
+        """
+
+        u_boot_console.log.action(
+            'Stopping long-running U-Boot ums shell command')
+        u_boot_console.ctrlc()
+        u_boot_utils.wait_until_file_open_fails(host_ums_part_node,
+            ignore_errors)
+
+    ignore_cleanup_errors = True
+    try:
+        start_ums()
+        if not have_writable_fs_partition:
+            # Skip filesystem-based testing if not configured
+            return
+        try:
+            mount()
+            u_boot_console.log.action('Writing test file via UMS')
+            cmd = ('rm', '-f', mounted_test_fn)
+            u_boot_utils.run_and_log(u_boot_console, cmd)
+            if os.path.exists(mounted_test_fn):
+                raise Exception('Could not rm target UMS test file')
+            cmd = ('cp', test_f.abs_fn, mounted_test_fn)
+            u_boot_utils.run_and_log(u_boot_console, cmd)
+            ignore_cleanup_errors = False
+        finally:
+            umount(ignore_errors=ignore_cleanup_errors)
+    finally:
+        stop_ums(ignore_errors=ignore_cleanup_errors)
+
+    ignore_cleanup_errors = True
+    try:
+        start_ums()
+        try:
+            mount()
+            u_boot_console.log.action('Reading test file back via UMS')
+            read_back_hash = u_boot_utils.md5sum_file(mounted_test_fn)
+            cmd = ('rm', '-f', mounted_test_fn)
+            u_boot_utils.run_and_log(u_boot_console, cmd)
+            ignore_cleanup_errors = False
+        finally:
+            umount(ignore_errors=ignore_cleanup_errors)
+    finally:
+        stop_ums(ignore_errors=ignore_cleanup_errors)
+
+    written_hash = test_f.content_hash
+    assert(written_hash == read_back_hash)
diff --git a/test/py/tests/test_unknown_cmd.py b/test/py/tests/test_unknown_cmd.py
index 2de93e0..c27ab49 100644
--- a/test/py/tests/test_unknown_cmd.py
+++ b/test/py/tests/test_unknown_cmd.py
@@ -4,8 +4,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
 def test_unknown_command(u_boot_console):
-    '''Test that executing an unknown command causes U-Boot to print an
-    error.'''
+    """Test that executing an unknown command causes U-Boot to print an
+    error."""
 
     # The "unknown command" error is actively expected here,
     # so error detection for it is disabled.
diff --git a/test/py/u_boot_console_base.py b/test/py/u_boot_console_base.py
index 520f9a9..392f8cb 100644
--- a/test/py/u_boot_console_base.py
+++ b/test/py/u_boot_console_base.py
@@ -14,6 +14,7 @@ import os
 import pytest
 import re
 import sys
+import u_boot_spawn
 
 # Regexes for text we expect U-Boot to send to the console.
 pattern_u_boot_spl_signon = re.compile('(U-Boot SPL \\d{4}\\.\\d{2}-[^\r\n]*)')
@@ -21,14 +22,27 @@ pattern_u_boot_main_signon = re.compile('(U-Boot \\d{4}\\.\\d{2}-[^\r\n]*)')
 pattern_stop_autoboot_prompt = re.compile('Hit any key to stop autoboot: ')
 pattern_unknown_command = re.compile('Unknown command \'.*\' - try \'help\'')
 pattern_error_notification = re.compile('## Error: ')
+pattern_error_please_reset = re.compile('### ERROR ### Please RESET the board ###')
+
+PAT_ID = 0
+PAT_RE = 1
+
+bad_pattern_defs = (
+    ('spl_signon', pattern_u_boot_spl_signon),
+    ('main_signon', pattern_u_boot_main_signon),
+    ('stop_autoboot_prompt', pattern_stop_autoboot_prompt),
+    ('unknown_command', pattern_unknown_command),
+    ('error_notification', pattern_error_notification),
+    ('error_please_reset', pattern_error_please_reset),
+)
 
 class ConsoleDisableCheck(object):
-    '''Context manager (for Python's with statement) that temporarily disables
+    """Context manager (for Python's with statement) that temporarily disables
     the specified console output error check. This is useful when deliberately
     executing a command that is known to trigger one of the error checks, in
     order to test that the error condition is actually raised. This class is
     used internally by ConsoleBase::disable_check(); it is not intended for
-    direct usage.'''
+    direct usage."""
 
     def __init__(self, console, check_type):
         self.console = console
@@ -36,18 +50,20 @@ class ConsoleDisableCheck(object):
 
     def __enter__(self):
         self.console.disable_check_count[self.check_type] += 1
+        self.console.eval_bad_patterns()
 
     def __exit__(self, extype, value, traceback):
         self.console.disable_check_count[self.check_type] -= 1
+        self.console.eval_bad_patterns()
 
 class ConsoleBase(object):
-    '''The interface through which test functions interact with the U-Boot
+    """The interface through which test functions interact with the U-Boot
     console. This primarily involves executing shell commands, capturing their
     results, and checking for common error conditions. Some common utilities
-    are also provided too.'''
+    are also provided too."""
 
     def __init__(self, log, config, max_fifo_fill):
-        '''Initialize a U-Boot console connection.
+        """Initialize a U-Boot console connection.
 
         Can only usefully be called by sub-classes.
 
@@ -64,7 +80,7 @@ class ConsoleBase(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.log = log
         self.config = config
@@ -76,19 +92,20 @@ class ConsoleBase(object):
         self.prompt = self.config.buildconfig['config_sys_prompt'][1:-1]
         self.prompt_escaped = re.escape(self.prompt)
         self.p = None
-        self.disable_check_count = {
-            'spl_signon': 0,
-            'main_signon': 0,
-            'unknown_command': 0,
-            'error_notification': 0,
-        }
+        self.disable_check_count = {pat[PAT_ID]: 0 for pat in bad_pattern_defs}
+        self.eval_bad_patterns()
 
         self.at_prompt = False
         self.at_prompt_logevt = None
-        self.ram_base = None
+
+    def eval_bad_patterns(self):
+        self.bad_patterns = [pat[PAT_RE] for pat in bad_pattern_defs \
+            if self.disable_check_count[pat[PAT_ID]] == 0]
+        self.bad_pattern_ids = [pat[PAT_ID] for pat in bad_pattern_defs \
+            if self.disable_check_count[pat[PAT_ID]] == 0]
 
     def close(self):
-        '''Terminate the connection to the U-Boot console.
+        """Terminate the connection to the U-Boot console.
 
         This function is only useful once all interaction with U-Boot is
         complete. Once this function is called, data cannot be sent to or
@@ -99,7 +116,7 @@ class ConsoleBase(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         if self.p:
             self.p.close()
@@ -107,7 +124,7 @@ class ConsoleBase(object):
 
     def run_command(self, cmd, wait_for_echo=True, send_nl=True,
             wait_for_prompt=True):
-        '''Execute a command via the U-Boot console.
+        """Execute a command via the U-Boot console.
 
         The command is always sent to U-Boot.
 
@@ -142,29 +159,12 @@ class ConsoleBase(object):
                 The output from U-Boot during command execution. In other
                 words, the text U-Boot emitted between the point it echod the
                 command string and emitted the subsequent command prompts.
-        '''
-
-        self.ensure_spawned()
+        """
 
         if self.at_prompt and \
                 self.at_prompt_logevt != self.logstream.logfile.cur_evt:
             self.logstream.write(self.prompt, implicit=True)
 
-        bad_patterns = []
-        bad_pattern_ids = []
-        if (self.disable_check_count['spl_signon'] == 0 and
-                self.u_boot_spl_signon):
-            bad_patterns.append(self.u_boot_spl_signon_escaped)
-            bad_pattern_ids.append('SPL signon')
-        if self.disable_check_count['main_signon'] == 0:
-            bad_patterns.append(self.u_boot_main_signon_escaped)
-            bad_pattern_ids.append('U-Boot main signon')
-        if self.disable_check_count['unknown_command'] == 0:
-            bad_patterns.append(pattern_unknown_command)
-            bad_pattern_ids.append('Unknown command')
-        if self.disable_check_count['error_notification'] == 0:
-            bad_patterns.append(pattern_error_notification)
-            bad_pattern_ids.append('Error notification')
         try:
             self.at_prompt = False
             if send_nl:
@@ -178,18 +178,18 @@ class ConsoleBase(object):
                     continue
                 chunk = re.escape(chunk)
                 chunk = chunk.replace('\\\n', '[\r\n]')
-                m = self.p.expect([chunk] + bad_patterns)
+                m = self.p.expect([chunk] + self.bad_patterns)
                 if m != 0:
                     self.at_prompt = False
                     raise Exception('Bad pattern found on console: ' +
-                                    bad_pattern_ids[m - 1])
+                                    self.bad_pattern_ids[m - 1])
             if not wait_for_prompt:
                 return
-            m = self.p.expect([self.prompt_escaped] + bad_patterns)
+            m = self.p.expect([self.prompt_escaped] + self.bad_patterns)
             if m != 0:
                 self.at_prompt = False
                 raise Exception('Bad pattern found on console: ' +
-                                bad_pattern_ids[m - 1])
+                                self.bad_pattern_ids[m - 1])
             self.at_prompt = True
             self.at_prompt_logevt = self.logstream.logfile.cur_evt
             # Only strip \r\n; space/TAB might be significant if testing
@@ -201,7 +201,7 @@ class ConsoleBase(object):
             raise
 
     def ctrlc(self):
-        '''Send a CTRL-C character to U-Boot.
+        """Send a CTRL-C character to U-Boot.
 
         This is useful in order to stop execution of long-running synchronous
         commands such as "ums".
@@ -211,12 +211,72 @@ class ConsoleBase(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
+        self.log.action('Sending Ctrl-C')
         self.run_command(chr(3), wait_for_echo=False, send_nl=False)
 
+    def wait_for(self, text):
+        """Wait for a pattern to be emitted by U-Boot.
+
+        This is useful when a long-running command such as "dfu" is executing,
+        and it periodically emits some text that should show up at a specific
+        location in the log file.
+
+        Args:
+            text: The text to wait for; either a string (containing raw text,
+                not a regular expression) or an re object.
+
+        Returns:
+            Nothing.
+        """
+
+        if type(text) == type(''):
+            text = re.escape(text)
+        m = self.p.expect([text] + self.bad_patterns)
+        if m != 0:
+            raise Exception('Bad pattern found on console: ' +
+                            self.bad_pattern_ids[m - 1])
+
+    def drain_console(self):
+        """Read from and log the U-Boot console for a short time.
+
+        U-Boot's console output is only logged when the test code actively
+        waits for U-Boot to emit specific data. There are cases where tests
+        can fail without doing this. For example, if a test asks U-Boot to
+        enable USB device mode, then polls until a host-side device node
+        exists. In such a case, it is useful to log U-Boot's console output
+        in case U-Boot printed clues as to why the host-side even did not
+        occur. This function will do that.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        """
+
+        # If we are already not connected to U-Boot, there's nothing to drain.
+        # This should only happen when a previous call to run_command() or
+        # wait_for() failed (and hence the output has already been logged), or
+        # the system is shutting down.
+        if not self.p:
+            return
+
+        orig_timeout = self.p.timeout
+        try:
+            # Drain the log for a relatively short time.
+            self.p.timeout = 1000
+            # Wait for something U-Boot will likely never send. This will
+            # cause the console output to be read and logged.
+            self.p.expect(['This should never match U-Boot output'])
+        except u_boot_spawn.Timeout:
+            pass
+        finally:
+            self.p.timeout = orig_timeout
+
     def ensure_spawned(self):
-        '''Ensure a connection to a correctly running U-Boot instance.
+        """Ensure a connection to a correctly running U-Boot instance.
 
         This may require spawning a new Sandbox process or resetting target
         hardware, as defined by the implementation sub-class.
@@ -228,7 +288,7 @@ class ConsoleBase(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         if self.p:
             return
@@ -243,26 +303,30 @@ class ConsoleBase(object):
             self.p.timeout = 30000
             self.p.logfile_read = self.logstream
             if self.config.buildconfig.get('CONFIG_SPL', False) == 'y':
-                self.p.expect([pattern_u_boot_spl_signon])
-                self.u_boot_spl_signon = self.p.after
-                self.u_boot_spl_signon_escaped = re.escape(self.p.after)
-            else:
-                self.u_boot_spl_signon = None
-            self.p.expect([pattern_u_boot_main_signon])
-            self.u_boot_main_signon = self.p.after
-            self.u_boot_main_signon_escaped = re.escape(self.p.after)
-            build_idx = self.u_boot_main_signon.find(', Build:')
+                m = self.p.expect([pattern_u_boot_spl_signon] + self.bad_patterns)
+                if m != 0:
+                    raise Exception('Bad pattern found on console: ' +
+                                    self.bad_pattern_ids[m - 1])
+            m = self.p.expect([pattern_u_boot_main_signon] + self.bad_patterns)
+            if m != 0:
+                raise Exception('Bad pattern found on console: ' +
+                                self.bad_pattern_ids[m - 1])
+            signon = self.p.after
+            build_idx = signon.find(', Build:')
             if build_idx == -1:
-                self.u_boot_version_string = self.u_boot_main_signon
+                self.u_boot_version_string = signon
             else:
-                self.u_boot_version_string = self.u_boot_main_signon[:build_idx]
+                self.u_boot_version_string = signon[:build_idx]
             while True:
-                match = self.p.expect([self.prompt_escaped,
-                                       pattern_stop_autoboot_prompt])
-                if match == 1:
+                m = self.p.expect([self.prompt_escaped,
+                    pattern_stop_autoboot_prompt] + self.bad_patterns)
+                if m == 0:
+                    break
+                if m == 1:
                     self.p.send(chr(3)) # CTRL-C
                     continue
-                break
+                raise Exception('Bad pattern found on console: ' +
+                                self.bad_pattern_ids[m - 2])
             self.at_prompt = True
             self.at_prompt_logevt = self.logstream.logfile.cur_evt
         except Exception as ex:
@@ -271,7 +335,7 @@ class ConsoleBase(object):
             raise
 
     def cleanup_spawn(self):
-        '''Shut down all interaction with the U-Boot instance.
+        """Shut down all interaction with the U-Boot instance.
 
         This is used when an error is detected prior to re-establishing a
         connection with a fresh U-Boot instance.
@@ -283,7 +347,7 @@ class ConsoleBase(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         try:
             if self.p:
@@ -293,7 +357,7 @@ class ConsoleBase(object):
         self.p = None
 
     def validate_version_string_in_text(self, text):
-        '''Assert that a command's output includes the U-Boot signon message.
+        """Assert that a command's output includes the U-Boot signon message.
 
         This is primarily useful for validating the "version" command without
         duplicating the signon text regex in a test function.
@@ -303,12 +367,12 @@ class ConsoleBase(object):
 
         Returns:
             Nothing. An exception is raised if the validation fails.
-        '''
+        """
 
         assert(self.u_boot_version_string in text)
 
     def disable_check(self, check_type):
-        '''Temporarily disable an error check of U-Boot's output.
+        """Temporarily disable an error check of U-Boot's output.
 
         Create a new context manager (for use with the "with" statement) which
         temporarily disables a particular console output error check.
@@ -319,42 +383,6 @@ class ConsoleBase(object):
 
         Returns:
             A context manager object.
-        '''
+        """
 
         return ConsoleDisableCheck(self, check_type)
-
-    def find_ram_base(self):
-        '''Find the running U-Boot's RAM location.
-
-        Probe the running U-Boot to determine the address of the first bank
-        of RAM. This is useful for tests that test reading/writing RAM, or
-        load/save files that aren't associated with some standard address
-        typically represented in an environment variable such as
-        ${kernel_addr_r}. The value is cached so that it only needs to be
-        actively read once.
-
-        Args:
-            None.
-
-        Returns:
-            The address of U-Boot's first RAM bank, as an integer.
-        '''
-
-        if self.config.buildconfig.get('config_cmd_bdi', 'n') != 'y':
-            pytest.skip('bdinfo command not supported')
-        if self.ram_base == -1:
-            pytest.skip('Previously failed to find RAM bank start')
-        if self.ram_base is not None:
-            return self.ram_base
-
-        with self.log.section('find_ram_base'):
-            response = self.run_command('bdinfo')
-            for l in response.split('\n'):
-                if '-> start' in l:
-                    self.ram_base = int(l.split('=')[1].strip(), 16)
-                    break
-            if self.ram_base is None:
-                self.ram_base = -1
-                raise Exception('Failed to find RAM bank start in `bdinfo`')
-
-        return self.ram_base
diff --git a/test/py/u_boot_console_exec_attach.py b/test/py/u_boot_console_exec_attach.py
index 0ca9e7c..19520cb 100644
--- a/test/py/u_boot_console_exec_attach.py
+++ b/test/py/u_boot_console_exec_attach.py
@@ -11,15 +11,15 @@ from u_boot_spawn import Spawn
 from u_boot_console_base import ConsoleBase
 
 class ConsoleExecAttach(ConsoleBase):
-    '''Represents a physical connection to a U-Boot console, typically via a
+    """Represents a physical connection to a U-Boot console, typically via a
     serial port. This implementation executes a sub-process to attach to the
     console, expecting that the stdin/out of the sub-process will be forwarded
     to/from the physical hardware. This approach isolates the test infra-
     structure from the user-/installation-specific details of how to
-    communicate with, and the identity of, serial ports etc.'''
+    communicate with, and the identity of, serial ports etc."""
 
     def __init__(self, log, config):
-        '''Initialize a U-Boot console connection.
+        """Initialize a U-Boot console connection.
 
         Args:
             log: A multiplexed_log.Logfile instance.
@@ -27,7 +27,7 @@ class ConsoleExecAttach(ConsoleBase):
 
         Returns:
             Nothing.
-        '''
+        """
 
         # The max_fifo_fill value might need tweaking per-board/-SoC?
         # 1 would be safe anywhere, but is very slow (a pexpect issue?).
@@ -42,7 +42,7 @@ class ConsoleExecAttach(ConsoleBase):
         runner.close()
 
     def get_spawn(self):
-        '''Connect to a fresh U-Boot instance.
+        """Connect to a fresh U-Boot instance.
 
         The target board is reset, so that U-Boot begins running from scratch.
 
@@ -51,7 +51,7 @@ class ConsoleExecAttach(ConsoleBase):
 
         Returns:
             A u_boot_spawn.Spawn object that is attached to U-Boot.
-        '''
+        """
 
         args = [self.config.board_type, self.config.board_identity]
         s = Spawn(['u-boot-test-console'] + args)
diff --git a/test/py/u_boot_console_sandbox.py b/test/py/u_boot_console_sandbox.py
index 88b137e..a7263f3 100644
--- a/test/py/u_boot_console_sandbox.py
+++ b/test/py/u_boot_console_sandbox.py
@@ -10,11 +10,11 @@ from u_boot_spawn import Spawn
 from u_boot_console_base import ConsoleBase
 
 class ConsoleSandbox(ConsoleBase):
-    '''Represents a connection to a sandbox U-Boot console, executed as a sub-
-    process.'''
+    """Represents a connection to a sandbox U-Boot console, executed as a sub-
+    process."""
 
     def __init__(self, log, config):
-        '''Initialize a U-Boot console connection.
+        """Initialize a U-Boot console connection.
 
         Args:
             log: A multiplexed_log.Logfile instance.
@@ -22,12 +22,12 @@ class ConsoleSandbox(ConsoleBase):
 
         Returns:
             Nothing.
-        '''
+        """
 
         super(ConsoleSandbox, self).__init__(log, config, max_fifo_fill=1024)
 
     def get_spawn(self):
-        '''Connect to a fresh U-Boot instance.
+        """Connect to a fresh U-Boot instance.
 
         A new sandbox process is created, so that U-Boot begins running from
         scratch.
@@ -37,26 +37,30 @@ class ConsoleSandbox(ConsoleBase):
 
         Returns:
             A u_boot_spawn.Spawn object that is attached to U-Boot.
-        '''
+        """
 
-        return Spawn([self.config.build_dir + '/u-boot'])
+        cmd = [
+            self.config.build_dir + '/u-boot',
+            '-d',
+            self.config.build_dir + '/arch/sandbox/dts/test.dtb'
+        ]
+        return Spawn(cmd, cwd=self.config.source_dir)
 
     def kill(self, sig):
-        '''Send a specific Unix signal to the sandbox process.
+        """Send a specific Unix signal to the sandbox process.
 
         Args:
             sig: The Unix signal to send to the process.
 
         Returns:
             Nothing.
-        '''
+        """
 
-        self.ensure_spawned()
         self.log.action('kill %d' % sig)
         self.p.kill(sig)
 
     def validate_exited(self):
-        '''Determine whether the sandbox process has exited.
+        """Determine whether the sandbox process has exited.
 
         If required, this function waits a reasonable time for the process to
         exit.
@@ -66,7 +70,7 @@ class ConsoleSandbox(ConsoleBase):
 
         Returns:
             Boolean indicating whether the process has exited.
-        '''
+        """
 
         p = self.p
         self.p = None
diff --git a/test/py/u_boot_spawn.py b/test/py/u_boot_spawn.py
index 1baee63..0f52d3e 100644
--- a/test/py/u_boot_spawn.py
+++ b/test/py/u_boot_spawn.py
@@ -12,23 +12,25 @@ import select
 import time
 
 class Timeout(Exception):
-    '''An exception sub-class that indicates that a timeout occurred.'''
+    """An exception sub-class that indicates that a timeout occurred."""
     pass
 
 class Spawn(object):
-    '''Represents the stdio of a freshly created sub-process. Commands may be
+    """Represents the stdio of a freshly created sub-process. Commands may be
     sent to the process, and responses waited for.
-    '''
+    """
 
-    def __init__(self, args):
-        '''Spawn (fork/exec) the sub-process.
+    def __init__(self, args, cwd=None):
+        """Spawn (fork/exec) the sub-process.
 
         Args:
-            args: array of processs arguments. argv[0] is the command to execute.
+            args: array of processs arguments. argv[0] is the command to
+              execute.
+            cwd: the directory to run the process in, or None for no change.
 
         Returns:
             Nothing.
-        '''
+        """
 
         self.waited = False
         self.buf = ''
@@ -44,6 +46,8 @@ class Spawn(object):
                 # run under "go" (www.go.cd). Perhaps this happens under any
                 # background (non-interactive) system?
                 signal.signal(signal.SIGHUP, signal.SIG_DFL)
+                if cwd:
+                    os.chdir(cwd)
                 os.execvp(args[0], args)
             except:
                 print 'CHILD EXECEPTION:'
@@ -56,26 +60,26 @@ class Spawn(object):
         self.poll.register(self.fd, select.POLLIN | select.POLLPRI | select.POLLERR | select.POLLHUP | select.POLLNVAL)
 
     def kill(self, sig):
-        '''Send unix signal "sig" to the child process.
+        """Send unix signal "sig" to the child process.
 
         Args:
             sig: The signal number to send.
 
         Returns:
             Nothing.
-        '''
+        """
 
         os.kill(self.pid, sig)
 
     def isalive(self):
-        '''Determine whether the child process is still running.
+        """Determine whether the child process is still running.
 
         Args:
             None.
 
         Returns:
             Boolean indicating whether process is alive.
-        '''
+        """
 
         if self.waited:
             return False
@@ -88,19 +92,19 @@ class Spawn(object):
         return False
 
     def send(self, data):
-        '''Send data to the sub-process's stdin.
+        """Send data to the sub-process's stdin.
 
         Args:
             data: The data to send to the process.
 
         Returns:
             Nothing.
-        '''
+        """
 
         os.write(self.fd, data)
 
     def expect(self, patterns):
-        '''Wait for the sub-process to emit specific data.
+        """Wait for the sub-process to emit specific data.
 
         This function waits for the process to emit one pattern from the
         supplied list of patterns, or for a timeout to occur.
@@ -116,12 +120,13 @@ class Spawn(object):
         Notable exceptions:
             Timeout, if the process did not emit any of the patterns within
             the expected time.
-        '''
+        """
 
         for pi in xrange(len(patterns)):
             if type(patterns[pi]) == type(''):
                 patterns[pi] = re.compile(patterns[pi])
 
+        tstart_s = time.time()
         try:
             while True:
                 earliest_m = None
@@ -131,7 +136,7 @@ class Spawn(object):
                     m = pattern.search(self.buf)
                     if not m:
                         continue
-                    if earliest_m and m.start() > earliest_m.start():
+                    if earliest_m and m.start() >= earliest_m.start():
                         continue
                     earliest_m = m
                     earliest_pi = pi
@@ -142,7 +147,11 @@ class Spawn(object):
                     self.after = self.buf[pos:posafter]
                     self.buf = self.buf[posafter:]
                     return earliest_pi
-                events = self.poll.poll(self.timeout)
+                tnow_s = time.time()
+                tdelta_ms = (tnow_s - tstart_s) * 1000
+                if tdelta_ms > self.timeout:
+                    raise Timeout()
+                events = self.poll.poll(self.timeout - tdelta_ms)
                 if not events:
                     raise Timeout()
                 c = os.read(self.fd, 1024)
@@ -156,7 +165,7 @@ class Spawn(object):
                 self.logfile_read.flush()
 
     def close(self):
-        '''Close the stdio connection to the sub-process.
+        """Close the stdio connection to the sub-process.
 
         This also waits a reasonable time for the sub-process to stop running.
 
@@ -165,7 +174,7 @@ class Spawn(object):
 
         Returns:
             Nothing.
-        '''
+        """
 
         os.close(self.fd)
         for i in xrange(100):
diff --git a/test/py/u_boot_utils.py b/test/py/u_boot_utils.py
new file mode 100644
index 0000000..72d24e4
--- /dev/null
+++ b/test/py/u_boot_utils.py
@@ -0,0 +1,209 @@
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Utility code shared across multiple tests.
+
+import hashlib
+import os
+import os.path
+import sys
+import time
+
+def md5sum_data(data):
+    """Calculate the MD5 hash of some data.
+
+    Args:
+        data: The data to hash.
+
+    Returns:
+        The hash of the data, as a binary string.
+    """
+
+    h = hashlib.md5()
+    h.update(data)
+    return h.digest()
+
+def md5sum_file(fn, max_length=None):
+    """Calculate the MD5 hash of the contents of a file.
+
+    Args:
+        fn: The filename of the file to hash.
+        max_length: The number of bytes to hash. If the file has more
+            bytes than this, they will be ignored. If None or omitted, the
+            entire file will be hashed.
+
+    Returns:
+        The hash of the file content, as a binary string.
+    """
+
+    with open(fn, 'rb') as fh:
+        if max_length:
+            params = [max_length]
+        else:
+            params = []
+        data = fh.read(*params)
+    return md5sum_data(data)
+
+class PersistentRandomFile(object):
+    """Generate and store information about a persistent file containing
+    random data."""
+
+    def __init__(self, u_boot_console, fn, size):
+        """Create or process the persistent file.
+
+        If the file does not exist, it is generated.
+
+        If the file does exist, its content is hashed for later comparison.
+
+        These files are always located in the "persistent data directory" of
+        the current test run.
+
+        Args:
+            u_boot_console: A console connection to U-Boot.
+            fn: The filename (without path) to create.
+            size: The desired size of the file in bytes.
+
+        Returns:
+            Nothing.
+        """
+
+        self.fn = fn
+
+        self.abs_fn = u_boot_console.config.persistent_data_dir + '/' + fn
+
+        if os.path.exists(self.abs_fn):
+            u_boot_console.log.action('Persistent data file ' + self.abs_fn +
+                ' already exists')
+            self.content_hash = md5sum_file(self.abs_fn)
+        else:
+            u_boot_console.log.action('Generating ' + self.abs_fn +
+                ' (random, persistent, %d bytes)' % size)
+            data = os.urandom(size)
+            with open(self.abs_fn, 'wb') as fh:
+                fh.write(data)
+            self.content_hash = md5sum_data(data)
+
+def attempt_to_open_file(fn):
+    """Attempt to open a file, without throwing exceptions.
+
+    Any errors (exceptions) that occur during the attempt to open the file
+    are ignored. This is useful in order to test whether a file (in
+    particular, a device node) exists and can be successfully opened, in order
+    to poll for e.g. USB enumeration completion.
+
+    Args:
+        fn: The filename to attempt to open.
+
+    Returns:
+        An open file handle to the file, or None if the file could not be
+            opened.
+    """
+
+    try:
+        return open(fn, 'rb')
+    except:
+        return None
+
+def wait_until_open_succeeds(fn):
+    """Poll until a file can be opened, or a timeout occurs.
+
+    Continually attempt to open a file, and return when this succeeds, or
+    raise an exception after a timeout.
+
+    Args:
+        fn: The filename to attempt to open.
+
+    Returns:
+        An open file handle to the file.
+    """
+
+    for i in xrange(100):
+        fh = attempt_to_open_file(fn)
+        if fh:
+            return fh
+        time.sleep(0.1)
+    raise Exception('File could not be opened')
+
+def wait_until_file_open_fails(fn, ignore_errors):
+    """Poll until a file cannot be opened, or a timeout occurs.
+
+    Continually attempt to open a file, and return when this fails, or
+    raise an exception after a timeout.
+
+    Args:
+        fn: The filename to attempt to open.
+        ignore_errors: Indicate whether to ignore timeout errors. If True, the
+            function will simply return if a timeout occurs, otherwise an
+            exception will be raised.
+
+    Returns:
+        Nothing.
+    """
+
+    for i in xrange(100):
+        fh = attempt_to_open_file(fn)
+        if not fh:
+            return
+        fh.close()
+        time.sleep(0.1)
+    if ignore_errors:
+        return
+    raise Exception('File can still be opened')
+
+def run_and_log(u_boot_console, cmd, ignore_errors=False):
+    """Run a command and log its output.
+
+    Args:
+        u_boot_console: A console connection to U-Boot.
+        cmd: The command to run, as an array of argv[].
+        ignore_errors: Indicate whether to ignore errors. If True, the function
+            will simply return if the command cannot be executed or exits with
+            an error code, otherwise an exception will be raised if such
+            problems occur.
+
+    Returns:
+        Nothing.
+    """
+
+    runner = u_boot_console.log.get_runner(cmd[0], sys.stdout)
+    runner.run(cmd, ignore_errors=ignore_errors)
+    runner.close()
+
+ram_base = None
+def find_ram_base(u_boot_console):
+    """Find the running U-Boot's RAM location.
+
+    Probe the running U-Boot to determine the address of the first bank
+    of RAM. This is useful for tests that test reading/writing RAM, or
+    load/save files that aren't associated with some standard address
+    typically represented in an environment variable such as
+    ${kernel_addr_r}. The value is cached so that it only needs to be
+    actively read once.
+
+    Args:
+        u_boot_console: A console connection to U-Boot.
+
+    Returns:
+        The address of U-Boot's first RAM bank, as an integer.
+    """
+
+    global ram_base
+    if u_boot_console.config.buildconfig.get('config_cmd_bdi', 'n') != 'y':
+        pytest.skip('bdinfo command not supported')
+    if ram_base == -1:
+        pytest.skip('Previously failed to find RAM bank start')
+    if ram_base is not None:
+        return ram_base
+
+    with u_boot_console.log.section('find_ram_base'):
+        response = u_boot_console.run_command('bdinfo')
+        for l in response.split('\n'):
+            if '-> start' in l:
+                ram_base = int(l.split('=')[1].strip(), 16)
+                break
+        if ram_base is None:
+            ram_base = -1
+            raise Exception('Failed to find RAM bank start in `bdinfo`')
+
+    return ram_base