test/py: Implement pytest infrastructure

This tool aims to test U-Boot by executing U-Boot shell commands using the
console interface. A single top-level script exists to execute or attach
to the U-Boot console, run the entire script of tests against it, and
summarize the results. Advantages of this approach are:

- Testing is performed in the same way a user or script would interact
  with U-Boot; there can be no disconnect.
- There is no need to write or embed test-related code into U-Boot itself.
  It is asserted that writing test-related code in Python is simpler and
  more flexible that writing it all in C.
- It is reasonably simple to interact with U-Boot in this way.

A few simple tests are provided as examples. Soon, we should convert as
many as possible of the other tests in test/* and test/cmd_ut.c too.

The hook scripts, relay control utilities, and udev rules I use for my
own HW setup are published at https://github.com/swarren/uboot-test-hooks.

See README.md for more details!

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org> #v3

14 files changed, 2090 insertions, 0 deletions

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+*.pyc
diff --git a/test/py/README.md b/test/py/README.md
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+# U-Boot pytest suite
+
+## Introduction
+
+This tool aims to test U-Boot by executing U-Boot shell commands using the
+console interface. A single top-level script exists to execute or attach to the
+U-Boot console, run the entire script of tests against it, and summarize the
+results. Advantages of this approach are:
+
+- Testing is performed in the same way a user or script would interact with
+  U-Boot; there can be no disconnect.
+- There is no need to write or embed test-related code into U-Boot itself.
+  It is asserted that writing test-related code in Python is simpler and more
+  flexible that writing it all in C.
+- It is reasonably simple to interact with U-Boot in this way.
+
+## Requirements
+
+The test suite is implemented using pytest. Interaction with the U-Boot console
+involves executing some binary and interacting with its stdin/stdout. You will
+need to implement various "hook" scripts that are called by the test suite at
+the appropriate time.
+
+On Debian or Debian-like distributions, the following packages are required.
+Similar package names should exist in other distributions.
+
+| Package        | Version tested (Ubuntu 14.04) |
+| -------------- | ----------------------------- |
+| python         | 2.7.5-5ubuntu3                |
+| python-pytest  | 2.5.1-1                       |
+
+The test script supports either:
+
+- Executing a sandbox port of U-Boot on the local machine as a sub-process,
+  and interacting with it over stdin/stdout.
+- Executing an external "hook" scripts to flash a U-Boot binary onto a
+  physical board, attach to the board's console stream, and reset the board.
+  Further details are described later.
+
+### Using `virtualenv` to provide requirements
+
+Older distributions (e.g. Ubuntu 10.04) may not provide all the required
+packages, or may provide versions that are too old to run the test suite. One
+can use the Python `virtualenv` script to locally install more up-to-date
+versions of the required packages without interfering with the OS installation.
+For example:
+
+```bash
+$ cd /path/to/u-boot
+$ sudo apt-get install python python-virtualenv
+$ virtualenv venv
+$ . ./venv/bin/activate
+$ pip install pytest
+```
+
+## Testing sandbox
+
+To run the testsuite on the sandbox port (U-Boot built as a native user-space
+application), simply execute:
+
+```
+./test/py/test.py --bd sandbox --build
+```
+
+The `--bd` option tells the test suite which board type is being tested. This
+lets the test suite know which features the board has, and hence exactly what
+can be tested.
+
+The `--build` option tells U-Boot to compile U-Boot. Alternatively, you may
+omit this option and build U-Boot yourself, in whatever way you choose, before
+running the test script.
+
+The test script will attach to U-Boot, execute all valid tests for the board,
+then print a summary of the test process. A complete log of the test session
+will be written to `${build_dir}/test-log.html`. This is best viewed in a web
+browser, but may be read directly as plain text, perhaps with the aid of the
+`html2text` utility.
+
+## Command-line options
+
+- `--board-type`, `--bd`, `-B` set the type of the board to be tested. For
+  example, `sandbox` or `seaboard`.
+- `--board-identity`, `--id` set the identity of the board to be tested.
+  This allows differentiation between multiple instances of the same type of
+  physical board that are attached to the same host machine. This parameter is
+  not interpreted by the test script in any way, but rather is simply passed
+  to the hook scripts described below, and may be used in any site-specific
+  way deemed necessary.
+- `--build` indicates that the test script should compile U-Boot itself
+  before running the tests. If using this option, make sure that any
+  environment variables required by the build process are already set, such as
+  `$CROSS_COMPILE`.
+- `--build-dir` sets the directory containing the compiled U-Boot binaries.
+  If omitted, this is `${source_dir}/build-${board_type}`.
+- `--result-dir` sets the directory to write results, such as log files,
+  into. If omitted, the build directory is used.
+- `--persistent-data-dir` sets the directory used to store persistent test
+  data. This is test data that may be re-used across test runs, such as file-
+  system images.
+
+`pytest` also implements a number of its own command-line options. Please see
+`pytest` documentation for complete details. Execute `py.test --version` for
+a brief summary. Note that U-Boot's test.py script passes all command-line
+arguments directly to `pytest` for processing.
+
+## Testing real hardware
+
+The tools and techniques used to interact with real hardware will vary
+radically between different host and target systems, and the whims of the user.
+For this reason, the test suite does not attempt to directly interact with real
+hardware in any way. Rather, it executes a standardized set of "hook" scripts
+via `$PATH`. These scripts implement certain actions on behalf of the test
+suite. This keeps the test suite simple and isolated from system variances
+unrelated to U-Boot features.
+
+### Hook scripts
+
+#### Environment variables
+
+The following environment variables are set when running hook scripts:
+
+- `UBOOT_BOARD_TYPE` the board type being tested.
+- `UBOOT_BOARD_IDENTITY` the board identity being tested, or `na` if none was
+  specified.
+- `UBOOT_SOURCE_DIR` the U-Boot source directory.
+- `UBOOT_TEST_PY_DIR` the full path to `test/py/` in the source directory.
+- `UBOOT_BUILD_DIR` the U-Boot build directory.
+- `UBOOT_RESULT_DIR` the test result directory.
+- `UBOOT_PERSISTENT_DATA_DIR` the test peristent data directory.
+
+#### `u-boot-test-console`
+
+This script provides access to the U-Boot console. The script's stdin/stdout
+should be connected to the board's console. This process should continue to run
+indefinitely, until killed. The test suite will run this script in parallel
+with all other hooks.
+
+This script may be implemented e.g. by exec()ing `cu`, `kermit`, `conmux`, etc.
+
+If you are able to run U-Boot under a hardware simulator such as qemu, then
+you would likely spawn that simulator from this script. However, note that
+`u-boot-test-reset` may be called multiple times per test script run, and must
+cause U-Boot to start execution from scratch each time. Hopefully your
+simulator includes a virtual reset button! If not, you can launch the
+simulator from `u-boot-test-reset` instead, while arranging for this console
+process to always communicate with the current simulator instance.
+
+#### `u-boot-test-flash`
+
+Prior to running the test suite against a board, some arrangement must be made
+so that the board executes the particular U-Boot binary to be tested. Often,
+this involves writing the U-Boot binary to the board's flash ROM. The test
+suite calls this hook script for that purpose.
+
+This script should perform the entire flashing process synchronously; the
+script should only exit once flashing is complete, and a board reset will
+cause the newly flashed U-Boot binary to be executed.
+
+It is conceivable that this script will do nothing. This might be useful in
+the following cases:
+
+- Some other process has already written the desired U-Boot binary into the
+  board's flash prior to running the test suite.
+- The board allows U-Boot to be downloaded directly into RAM, and executed
+  from there. Use of this feature will reduce wear on the board's flash, so
+  may be preferable if available, and if cold boot testing of U-Boot is not
+  required. If this feature is used, the `u-boot-test-reset` script should
+  peform this download, since the board could conceivably be reset multiple
+  times in a single test run.
+
+It is up to the user to determine if those situations exist, and to code this
+hook script appropriately.
+
+This script will typically be implemented by calling out to some SoC- or
+board-specific vendor flashing utility.
+
+#### `u-boot-test-reset`
+
+Whenever the test suite needs to reset the target board, this script is
+executed. This is guaranteed to happen at least once, prior to executing the
+first test function. If any test fails, the test infra-structure will execute
+this script again to restore U-Boot to an operational state before running the
+next test function.
+
+This script will likely be implemented by communicating with some form of
+relay or electronic switch attached to the board's reset signal.
+
+The semantics of this script require that when it is executed, U-Boot will
+start running from scratch. If the U-Boot binary to be tested has been written
+to flash, pulsing the board's reset signal is likely all this script need do.
+However, in some scenarios, this script may perform other actions. For
+example, it may call out to some SoC- or board-specific vendor utility in order
+to download the U-Boot binary directly into RAM and execute it. This would
+avoid the need for `u-boot-test-flash` to actually write U-Boot to flash, thus
+saving wear on the flash chip(s).
+
+### Board-type-specific configuration
+
+Each board has a different configuration and behaviour. Many of these
+differences can be automatically detected by parsing the `.config` file in the
+build directory. However, some differences can't yet be handled automatically.
+
+For each board, an optional Python module `u_boot_board_${board_type}` may exist
+to provide board-specific information to the test script. Any global value
+defined in these modules is available for use by any test function. The data
+contained in these scripts must be purely derived from U-Boot source code.
+Hence, these configuration files are part of the U-Boot source tree too.
+
+### Execution environment configuration
+
+Each user's hardware setup may enable testing different subsets of the features
+implemented by a particular board's configuration of U-Boot. For example, a
+U-Boot configuration may support USB device mode and USB Mass Storage, but this
+can only be tested if a USB cable is connected between the board and the host
+machine running the test script.
+
+For each board, optional Python modules `u_boot_boardenv_${board_type}` and
+`u_boot_boardenv_${board_type}_${board_identity}` may exist to provide
+board-specific and board-identity-specific information to the test script. Any
+global value defined in these modules is available for use by any test
+function. The data contained in these is specific to a particular user's
+hardware configuration. Hence, these configuration files are not part of the
+U-Boot source tree, and should be installed outside of the source tree. Users
+should set `$PYTHONPATH` prior to running the test script to allow these
+modules to be loaded.
+
+### Board module parameter usage
+
+The test scripts rely on the following variables being defined by the board
+module:
+
+- None at present.
+
+### U-Boot `.config` feature usage
+
+The test scripts rely on various U-Boot `.config` features, either directly in
+order to test those features, or indirectly in order to query information from
+the running U-Boot instance in order to test other features.
+
+One example is that testing of the `md` command requires knowledge of a RAM
+address to use for the test. This data is parsed from the output of the
+`bdinfo` command, and hence relies on CONFIG_CMD_BDI being enabled.
+
+For a complete list of dependencies, please search the test scripts for
+instances of:
+
+- `buildconfig.get(...`
+- `@pytest.mark.buildconfigspec(...`
+
+### Complete invocation example
+
+Assuming that you have installed the hook scripts into $HOME/ubtest/bin, and
+any required environment configuration Python modules into $HOME/ubtest/py,
+then you would likely invoke the test script as follows:
+
+If U-Boot has already been built:
+
+```bash
+PATH=$HOME/ubtest/bin:$PATH \
+    PYTHONPATH=${HOME}/ubtest/py:${PYTHONPATH} \
+    ./test/py/test.py --bd seaboard
+```
+
+If you want the test script to compile U-Boot for you too, then you likely
+need to set `$CROSS_COMPILE` to allow this, and invoke the test script as
+follow:
+
+```bash
+CROSS_COMPILE=arm-none-eabi- \
+    PATH=$HOME/ubtest/bin:$PATH \
+    PYTHONPATH=${HOME}/ubtest/py:${PYTHONPATH} \
+    ./test/py/test.py --bd seaboard --build
+```
+
+## Writing tests
+
+Please refer to the pytest documentation for details of writing pytest tests.
+Details specific to the U-Boot test suite are described below.
+
+A test fixture named `u_boot_console` should be used by each test function. This
+provides the means to interact with the U-Boot console, and retrieve board and
+environment configuration information.
+
+The function `u_boot_console.run_command()` executes a shell command on the
+U-Boot console, and returns all output from that command. This allows
+validation or interpretation of the command output. This function validates
+that certain strings are not seen on the U-Boot console. These include shell
+error messages and the U-Boot sign-on message (in order to detect unexpected
+board resets). See the source of `u_boot_console_base.py` for a complete list of
+"bad" strings. Some test scenarios are expected to trigger these strings. Use
+`u_boot_console.disable_check()` to temporarily disable checking for specific
+strings. See `test_unknown_cmd.py` for an example.
+
+Board- and board-environment configuration values may be accessed as sub-fields
+of the `u_boot_console.config` object, for example
+`u_boot_console.config.ram_base`.
+
+Build configuration values (from `.config`) may be accessed via the dictionary
+`u_boot_console.config.buildconfig`, with keys equal to the Kconfig variable
+names.
diff --git a/test/py/conftest.py b/test/py/conftest.py
new file mode 100644
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--- /dev/null
+++ b/test/py/conftest.py
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+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Implementation of pytest run-time hook functions. These are invoked by
+# pytest at certain points during operation, e.g. startup, for each executed
+# test, at shutdown etc. These hooks perform functions such as:
+# - Parsing custom command-line options.
+# - Pullilng in user-specified board configuration.
+# - Creating the U-Boot console test fixture.
+# - Creating the HTML log file.
+# - Monitoring each test's results.
+# - Implementing custom pytest markers.
+
+import atexit
+import errno
+import os
+import os.path
+import pexpect
+import pytest
+from _pytest.runner import runtestprotocol
+import ConfigParser
+import StringIO
+import sys
+
+# Globals: The HTML log file, and the connection to the U-Boot console.
+log = None
+console = None
+
+def mkdir_p(path):
+    '''Create a directory path.
+
+    This includes creating any intermediate/parent directories. Any errors
+    caused due to already extant directories are ignored.
+
+    Args:
+        path: The directory path to create.
+
+    Returns:
+        Nothing.
+    '''
+
+    try:
+        os.makedirs(path)
+    except OSError as exc:
+        if exc.errno == errno.EEXIST and os.path.isdir(path):
+            pass
+        else:
+            raise
+
+def pytest_addoption(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=)')
+    parser.addoption('--result-dir', default=None,
+        help='U-Boot test result/tmp directory')
+    parser.addoption('--persistent-data-dir', default=None,
+        help='U-Boot test persistent generated data directory')
+    parser.addoption('--board-type', '--bd', '-B', default='sandbox',
+        help='U-Boot board type')
+    parser.addoption('--board-identity', '--id', default='na',
+        help='U-Boot board identity/instance')
+    parser.addoption('--build', default=False, action='store_true',
+        help='Compile U-Boot before running tests')
+
+def pytest_configure(config):
+    '''pytest hook: Perform custom initialization at startup time.
+
+    Args:
+        config: The pytest configuration.
+
+    Returns:
+        Nothing.
+    '''
+
+    global log
+    global console
+    global ubconfig
+
+    test_py_dir = os.path.dirname(os.path.abspath(__file__))
+    source_dir = os.path.dirname(os.path.dirname(test_py_dir))
+
+    board_type = config.getoption('board_type')
+    board_type_filename = board_type.replace('-', '_')
+
+    board_identity = config.getoption('board_identity')
+    board_identity_filename = board_identity.replace('-', '_')
+
+    build_dir = config.getoption('build_dir')
+    if not build_dir:
+        build_dir = source_dir + '/build-' + board_type
+    mkdir_p(build_dir)
+
+    result_dir = config.getoption('result_dir')
+    if not result_dir:
+        result_dir = build_dir
+    mkdir_p(result_dir)
+
+    persistent_data_dir = config.getoption('persistent_data_dir')
+    if not persistent_data_dir:
+        persistent_data_dir = build_dir + '/persistent-data'
+    mkdir_p(persistent_data_dir)
+
+    import multiplexed_log
+    log = multiplexed_log.Logfile(result_dir + '/test-log.html')
+
+    if config.getoption('build'):
+        if build_dir != source_dir:
+            o_opt = 'O=%s' % build_dir
+        else:
+            o_opt = ''
+        cmds = (
+            ['make', o_opt, '-s', board_type + '_defconfig'],
+            ['make', o_opt, '-s', '-j8'],
+        )
+        runner = log.get_runner('make', sys.stdout)
+        for cmd in cmds:
+            runner.run(cmd, cwd=source_dir)
+        runner.close()
+
+    class ArbitraryAttributeContainer(object):
+        pass
+
+    ubconfig = ArbitraryAttributeContainer()
+    ubconfig.brd = dict()
+    ubconfig.env = dict()
+
+    modules = [
+        (ubconfig.brd, 'u_boot_board_' + board_type_filename),
+        (ubconfig.env, 'u_boot_boardenv_' + board_type_filename),
+        (ubconfig.env, 'u_boot_boardenv_' + board_type_filename + '_' +
+            board_identity_filename),
+    ]
+    for (dict_to_fill, module_name) in modules:
+        try:
+            module = __import__(module_name)
+        except ImportError:
+            continue
+        dict_to_fill.update(module.__dict__)
+
+    ubconfig.buildconfig = dict()
+
+    for conf_file in ('.config', 'include/autoconf.mk'):
+        dot_config = build_dir + '/' + conf_file
+        if not os.path.exists(dot_config):
+            raise Exception(conf_file + ' does not exist; ' +
+                'try passing --build option?')
+
+        with open(dot_config, 'rt') as f:
+            ini_str = '[root]\n' + f.read()
+            ini_sio = StringIO.StringIO(ini_str)
+            parser = ConfigParser.RawConfigParser()
+            parser.readfp(ini_sio)
+            ubconfig.buildconfig.update(parser.items('root'))
+
+    ubconfig.test_py_dir = test_py_dir
+    ubconfig.source_dir = source_dir
+    ubconfig.build_dir = build_dir
+    ubconfig.result_dir = result_dir
+    ubconfig.persistent_data_dir = persistent_data_dir
+    ubconfig.board_type = board_type
+    ubconfig.board_identity = board_identity
+
+    env_vars = (
+        'board_type',
+        'board_identity',
+        'source_dir',
+        'test_py_dir',
+        'build_dir',
+        'result_dir',
+        'persistent_data_dir',
+    )
+    for v in env_vars:
+        os.environ['U_BOOT_' + v.upper()] = getattr(ubconfig, v)
+
+    if board_type == 'sandbox':
+        import u_boot_console_sandbox
+        console = u_boot_console_sandbox.ConsoleSandbox(log, ubconfig)
+    else:
+        import u_boot_console_exec_attach
+        console = u_boot_console_exec_attach.ConsoleExecAttach(log, ubconfig)
+
+def pytest_generate_tests(metafunc):
+    '''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
+    find the list of values to use for those parameters, and the test is
+    parametrized so that it runs once for each combination of values.
+
+    Args:
+        metafunc: The pytest test function.
+
+    Returns:
+        Nothing.
+    '''
+
+    subconfigs = {
+        'brd': console.config.brd,
+        'env': console.config.env,
+    }
+    for fn in metafunc.fixturenames:
+        parts = fn.split('__')
+        if len(parts) < 2:
+            continue
+        if parts[0] not in subconfigs:
+            continue
+        subconfig = subconfigs[parts[0]]
+        vals = []
+        val = subconfig.get(fn, [])
+        # If that exact name is a key in the data source:
+        if val:
+            # ... use the dict value as a single parameter value.
+            vals = (val, )
+        else:
+            # ... 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 u_boot_console(request):
+    '''Generate the value of a test's u_boot_console fixture.
+
+    Args:
+        request: The pytest request.
+
+    Returns:
+        The fixture value.
+    '''
+
+    return console
+
+tests_not_run = set()
+tests_failed = set()
+tests_skipped = set()
+tests_passed = set()
+
+def pytest_itemcollected(item):
+    '''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.
+
+    Args:
+        item: The item that was collected.
+
+    Returns:
+        Nothing.
+    '''
+
+    tests_not_run.add(item.name)
+
+def cleanup():
+    '''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
+    or skipped tests.
+
+    Args:
+        None.
+
+    Returns:
+        Nothing.
+    '''
+
+    if console:
+        console.close()
+    if log:
+        log.status_pass('%d passed' % len(tests_passed))
+        if tests_skipped:
+            log.status_skipped('%d skipped' % len(tests_skipped))
+            for test in tests_skipped:
+                log.status_skipped('... ' + test)
+        if tests_failed:
+            log.status_fail('%d failed' % len(tests_failed))
+            for test in tests_failed:
+                log.status_fail('... ' + test)
+        if tests_not_run:
+            log.status_fail('%d not run' % len(tests_not_run))
+            for test in tests_not_run:
+                log.status_fail('... ' + test)
+        log.close()
+atexit.register(cleanup)
+
+def setup_boardspec(item):
+    '''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
+    marked to be skipped.
+
+    Args:
+        item: The pytest test item.
+
+    Returns:
+        Nothing.
+    '''
+
+    mark = item.get_marker('boardspec')
+    if not mark:
+        return
+    required_boards = []
+    for board in mark.args:
+        if board.startswith('!'):
+            if ubconfig.board_type == board[1:]:
+                pytest.skip('board not supported')
+                return
+        else:
+            required_boards.append(board)
+    if required_boards and ubconfig.board_type not in required_boards:
+        pytest.skip('board not supported')
+
+def setup_buildconfigspec(item):
+    '''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
+    have the required feature, the test is marked to be skipped.
+
+    Args:
+        item: The pytest test item.
+
+    Returns:
+        Nothing.
+    '''
+
+    mark = item.get_marker('buildconfigspec')
+    if not mark:
+        return
+    for option in mark.args:
+        if not ubconfig.buildconfig.get('config_' + option.lower(), None):
+            pytest.skip('.config feature not enabled')
+
+def pytest_runtest_setup(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.
+
+    Args:
+        item: The pytest test 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.
+
+    This hook wraps the standard pytest runtestprotocol() function in order
+    to acquire visibility into, and record, each test function's result.
+
+    Args:
+        item: The pytest test item to execute.
+        nextitem: The pytest test item that will be executed after this one.
+
+    Returns:
+        A list of pytest reports (test result data).
+    '''
+
+    reports = runtestprotocol(item, nextitem=nextitem)
+    failed = None
+    skipped = None
+    for report in reports:
+        if report.outcome == 'failed':
+            failed = report
+            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)
+    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')
+    except:
+        # If something went wrong with logging, it's better to let the test
+        # process continue, which may report other exceptions that triggered
+        # the logging issue (e.g. console.log wasn't created). Hence, just
+        # squash the exception. If the test setup failed due to e.g. syntax
+        # error somewhere else, this won't be seen. However, once that issue
+        # is fixed, if this exception still exists, it will then be logged as
+        # part of the test's stdout.
+        import traceback
+        print 'Exception occurred while logging runtest status:'
+        traceback.print_exc()
+        # FIXME: Can we force a test failure here?
+
+    log.end_section(item.name)
+
+    if failed:
+        console.cleanup_spawn()
+
+    return reports
diff --git a/test/py/multiplexed_log.css b/test/py/multiplexed_log.css
new file mode 100644
index 0000000000..50f7b90929
--- /dev/null
+++ b/test/py/multiplexed_log.css
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2015 Stephen Warren
+ * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+/*
+ * This provides pretty formatting of the HTML log file, e.g.
+ * - colored bars beside/above log sections for easily parsed delineation.
+ * - color highlighting of various messages.
+ */
+
+body {
+    background-color: black;
+    color: #ffffff;
+}
+
+pre {
+    margin-top: 0px;
+    margin-bottom: 0px;
+}
+
+.implicit {
+    color: #808080;
+}
+
+.section {
+    border-style: solid;
+    border-color: #303030;
+    border-width: 0px 0px 0px 5px;
+    padding-left: 5px
+}
+
+.section-header {
+    background-color: #303030;
+    margin-left: -5px;
+    margin-top: 5px;
+}
+
+.section-trailer {
+    display: none;
+}
+
+.stream {
+    border-style: solid;
+    border-color: #303030;
+    border-width: 0px 0px 0px 5px;
+    padding-left: 5px
+}
+
+.stream-header {
+    background-color: #303030;
+    margin-left: -5px;
+    margin-top: 5px;
+}
+
+.stream-trailer {
+    display: none;
+}
+
+.error {
+    color: #ff0000
+}
+
+.warning {
+    color: #ffff00
+}
+
+.info {
+    color: #808080
+}
+
+.action {
+    color: #8080ff
+}
+
+.status-pass {
+    color: #00ff00
+}
+
+.status-skipped {
+    color: #ffff00
+}
+
+.status-fail {
+    color: #ff0000
+}
diff --git a/test/py/multiplexed_log.py b/test/py/multiplexed_log.py
new file mode 100644
index 0000000000..48f2b51de1
--- /dev/null
+++ b/test/py/multiplexed_log.py
@@ -0,0 +1,515 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Generate an HTML-formatted log file containing multiple streams of data,
+# each represented in a well-delineated/-structured fashion.
+
+import cgi
+import os.path
+import shutil
+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 multiplexed log file. Objects of this type should be created by factory
+    functions in the Logfile class rather than directly.'''
+
+    def __init__(self, logfile, name, chained_file):
+        '''Initialize a new object.
+
+        Args:
+            logfile: The Logfile object to log to.
+            name: The name of this log stream.
+            chained_file: The file-like object to which all stream data should be
+            logged to in addition to logfile. Can be None.
+
+        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".
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        pass
+
+    def write(self, data, implicit=False):
+        '''Write data to the log stream.
+
+        Args:
+            data: The data to write tot he file.
+            implicit: Boolean indicating whether data actually appeared in the
+                stream, or was implicitly generated. A valid use-case is to
+                repeat a shell prompt at the start of each separate log
+                section, which makes the log sections more readable in
+                isolation.
+
+        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.
+
+        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 multiplexed log file. Objects of this type should be created by factory
+    functions in the Logfile class rather than directly.'''
+
+    def __init__(self, logfile, name, chained_file):
+        '''Initialize a new object.
+
+        Args:
+            logfile: The Logfile object to log to.
+            name: The name of this log stream or sub-process.
+            chained_file: The file-like object to which all stream data should
+                be logged to in addition to logfile. Can be None.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.logfile = logfile
+        self.name = name
+        self.chained_file = chained_file
+
+    def close(self):
+        '''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.
+
+        Args:
+            cmd: The command to execute.
+            cwd: The directory to run the command in. Can be None to use the
+                current directory.
+
+        Returns:
+            Nothing.
+        '''
+
+        msg = "+" + " ".join(cmd) + "\n"
+        if self.chained_file:
+            self.chained_file.write(msg)
+        self.logfile.write(self, msg)
+
+        try:
+            p = subprocess.Popen(cmd, cwd=cwd,
+                stdin=None, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+            (stdout, stderr) = p.communicate()
+            output = ''
+            if stdout:
+                if stderr:
+                    output += 'stdout:\n'
+                output += stdout
+            if stderr:
+                if stdout:
+                    output += 'stderr:\n'
+                output += stderr
+            exit_status = p.returncode
+            exception = None
+        except subprocess.CalledProcessError as cpe:
+            output = cpe.output
+            exit_status = cpe.returncode
+            exception = cpe
+        except Exception as e:
+            output = ''
+            exit_status = 0
+            exception = e
+        if output and not output.endswith('\n'):
+            output += '\n'
+        if exit_status and not exception:
+            exception = Exception('Exit code: ' + str(exit_status))
+        if exception:
+            output += str(exception) + '\n'
+        self.logfile.write(self, output)
+        if self.chained_file:
+            self.chained_file.write(output)
+        if exception:
+            raise exception
+
+class SectionCtxMgr(object):
+    '''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.'''
+
+    def __init__(self, log, marker):
+        '''Initialize a new object.
+
+        Args:
+            log: The Logfile object to log to.
+            marker: The name of the nested log section.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.log = log
+        self.marker = marker
+
+    def __enter__(self):
+        self.log.start_section(self.marker)
+
+    def __exit__(self, extype, value, traceback):
+        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.'''
+
+    def __init__(self, fn):
+        '''Initialize a new object.
+
+        Args:
+            fn: The filename to write to.
+
+        Returns:
+            Nothing.
+        '''
+
+        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("""\
+<html>
+<head>
+<link rel="stylesheet" type="text/css" href="multiplexed_log.css">
+</head>
+<body>
+<tt>
+""")
+
+    def close(self):
+        '''Close the log file.
+
+        After calling this function, no more data may be written to the log.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        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)))
+
+    def _escape(self, data):
+        '''Render data format suitable for inclusion in an HTML document.
+
+        This includes HTML-escaping certain characters, and translating
+        control characters to a hexadecimal representation.
+
+        Args:
+            data: The raw string data to be escaped.
+
+        Returns:
+            An escaped version of the data.
+        '''
+
+        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.
+
+        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.last_stream = None
+
+    def _note(self, note_type, msg):
+        '''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
+                accompanying multiplexed_log.css.
+            msg: The note/message to log.
+
+        Returns:
+            Nothing.
+        '''
+
+        self._terminate_stream()
+        self.f.write("<div class=\"" + note_type + "\">\n<pre>")
+        self.f.write(self._escape(msg))
+        self.f.write("\n</pre></div>\n")
+
+    def start_section(self, marker):
+        '''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")
+
+    def end_section(self, marker):
+        '''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.
+
+        Args:
+            marker: The name of the section that is ending.
+
+        Returns:
+            Nothing.
+        '''
+
+        if (not self.blocks) or (marker != self.blocks[-1]):
+            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")
+        self.blocks.pop()
+
+    def section(self, marker):
+        '''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
+        section of the log file.
+
+        Usage:
+            with log.section("somename"):
+                some test code
+
+        Args:
+            marker: The name of the nested section.
+
+        Returns:
+            A context manager object.
+        '''
+
+        return SectionCtxMgr(self, marker)
+
+    def error(self, msg):
+        '''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.
+
+        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.
+
+        Args:
+            msg: An informational message.
+
+        Returns:
+            Nothing.
+        '''
+
+        self._note("info", msg)
+
+    def action(self, msg):
+        '''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.
+
+        Args:
+            msg: A message describing 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).
+
+        Args:
+            msg: A message describing passed test(s).
+
+        Returns:
+            Nothing.
+        '''
+
+        self._note("status-skipped", msg)
+
+    def status_fail(self, msg):
+        '''Write a note to the log file describing failed test(s).
+
+        Args:
+            msg: A message describing passed 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.
+
+        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
+        handle any required interleaving of data (from multiple streams) in
+        the log, in a way that makes it obvious which stream each bit of data
+        came from.
+
+        Args:
+            name: The name of the stream.
+            chained_file: The file-like object to which all stream data should
+                be logged to in addition to this log. Can be None.
+
+        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.
+
+        Args:
+            name: The name of this sub-process.
+            chained_file: The file-like object to which all stream data should
+                be logged to in addition to logfile. Can be None.
+
+        Returns:
+            A RunAndLog object.
+        '''
+
+        return RunAndLog(self, name, chained_file)
+
+    def write(self, stream, data, implicit=False):
+        '''Write stream data into the log file.
+
+        This function should only be used by instances of LogfileStream or
+        RunAndLog.
+
+        Args:
+            stream: The stream whose data is being logged.
+            data: The data to log.
+            implicit: Boolean indicating whether data actually appeared in the
+                stream, or was implicitly generated. A valid use-case is to
+                repeat a shell prompt at the start of each separate log
+                section, which makes the log sections more readable in
+                isolation.
+
+        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>")
+        if implicit:
+            self.f.write("<span class=\"implicit\">")
+        self.f.write(self._escape(data))
+        if implicit:
+            self.f.write("</span>")
+        self.last_stream = stream
+
+    def flush(self):
+        '''Flush the log stream, to ensure correct log interleaving.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.f.flush()
diff --git a/test/py/pytest.ini b/test/py/pytest.ini
new file mode 100644
index 0000000000..67e514f420
--- /dev/null
+++ b/test/py/pytest.ini
@@ -0,0 +1,11 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Static configuration data for pytest. pytest reads this at startup time.
+
+[pytest]
+markers =
+    boardspec: U-Boot: Describes the set of boards a test can/can't run on.
+    buildconfigspec: U-Boot: Describes Kconfig/config-header constraints.
diff --git a/test/py/test.py b/test/py/test.py
new file mode 100755
index 0000000000..9c23898774
--- /dev/null
+++ b/test/py/test.py
@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Wrapper script to invoke pytest with the directory name that contains the
+# U-Boot tests.
+
+import os
+import os.path
+import sys
+
+# Get rid of argv[0]
+sys.argv.pop(0)
+
+# argv; py.test test_directory_name user-supplied-arguments
+args = ["py.test", os.path.dirname(__file__) + "/tests"]
+args.extend(sys.argv)
+
+try:
+    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, """
+exec(py.test) failed; perhaps you are missing some dependencies?
+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
new file mode 100644
index 0000000000..d262f0534e
--- /dev/null
+++ b/test/py/tests/test_000_version.py
@@ -0,0 +1,20 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# pytest runs tests the order of their module path, which is related to the
+# filename containing the test. This file is named such that it is sorted
+# first, simply as a very basic sanity check of the functionality of the U-Boot
+# command prompt.
+
+def test_version(u_boot_console):
+    '''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
+    # error detection is disabled since the sign-on message is expected.
+    with u_boot_console.disable_check('main_signon'):
+        response = u_boot_console.run_command('version')
+    # Ensure "version" printed what we expected.
+    u_boot_console.validate_version_string_in_text(response)
diff --git a/test/py/tests/test_help.py b/test/py/tests/test_help.py
new file mode 100644
index 0000000000..894f3b5f17
--- /dev/null
+++ b/test/py/tests/test_help.py
@@ -0,0 +1,9 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+def test_help(u_boot_console):
+    '''Test that the "help" command can be executed.'''
+
+    u_boot_console.run_command('help')
diff --git a/test/py/tests/test_unknown_cmd.py b/test/py/tests/test_unknown_cmd.py
new file mode 100644
index 0000000000..2de93e0026
--- /dev/null
+++ b/test/py/tests/test_unknown_cmd.py
@@ -0,0 +1,14 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# 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.'''
+
+    # The "unknown command" error is actively expected here,
+    # so error detection for it is disabled.
+    with u_boot_console.disable_check('unknown_command'):
+        response = u_boot_console.run_command('non_existent_cmd')
+    assert('Unknown command \'non_existent_cmd\' - try \'help\'' in response)
diff --git a/test/py/u_boot_console_base.py b/test/py/u_boot_console_base.py
new file mode 100644
index 0000000000..520f9a9e9f
--- /dev/null
+++ b/test/py/u_boot_console_base.py
@@ -0,0 +1,360 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Common logic to interact with U-Boot via the console. This class provides
+# the interface that tests use to execute U-Boot shell commands and wait for
+# their results. Sub-classes exist to perform board-type-specific setup
+# operations, such as spawning a sub-process for Sandbox, or attaching to the
+# serial console of real hardware.
+
+import multiplexed_log
+import os
+import pytest
+import re
+import sys
+
+# 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]*)')
+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: ')
+
+class ConsoleDisableCheck(object):
+    '''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.'''
+
+    def __init__(self, console, check_type):
+        self.console = console
+        self.check_type = check_type
+
+    def __enter__(self):
+        self.console.disable_check_count[self.check_type] += 1
+
+    def __exit__(self, extype, value, traceback):
+        self.console.disable_check_count[self.check_type] -= 1
+
+class ConsoleBase(object):
+    '''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.'''
+
+    def __init__(self, log, config, max_fifo_fill):
+        '''Initialize a U-Boot console connection.
+
+        Can only usefully be called by sub-classes.
+
+        Args:
+            log: A mulptiplex_log.Logfile object, to which the U-Boot output
+                will be logged.
+            config: A configuration data structure, as built by conftest.py.
+            max_fifo_fill: The maximum number of characters to send to U-Boot
+                command-line before waiting for U-Boot to echo the characters
+                back. For UART-based HW without HW flow control, this value
+                should be set less than the UART RX FIFO size to avoid
+                overflow, assuming that U-Boot can't keep up with full-rate
+                traffic at the baud rate.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.log = log
+        self.config = config
+        self.max_fifo_fill = max_fifo_fill
+
+        self.logstream = self.log.get_stream('console', sys.stdout)
+
+        # Array slice removes leading/trailing quotes
+        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.at_prompt = False
+        self.at_prompt_logevt = None
+        self.ram_base = None
+
+    def close(self):
+        '''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
+        received from U-Boot.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        if self.p:
+            self.p.close()
+        self.logstream.close()
+
+    def run_command(self, cmd, wait_for_echo=True, send_nl=True,
+            wait_for_prompt=True):
+        '''Execute a command via the U-Boot console.
+
+        The command is always sent to U-Boot.
+
+        U-Boot echoes any command back to its output, and this function
+        typically waits for that to occur. The wait can be disabled by setting
+        wait_for_echo=False, which is useful e.g. when sending CTRL-C to
+        interrupt a long-running command such as "ums".
+
+        Command execution is typically triggered by sending a newline
+        character. This can be disabled by setting send_nl=False, which is
+        also useful when sending CTRL-C.
+
+        This function typically waits for the command to finish executing, and
+        returns the console output that it generated. This can be disabled by
+        setting wait_for_prompt=False, which is useful when invoking a long-
+        running command such as "ums".
+
+        Args:
+            cmd: The command to send.
+            wait_for_each: Boolean indicating whether to wait for U-Boot to
+                echo the command text back to its output.
+            send_nl: Boolean indicating whether to send a newline character
+                after the command string.
+            wait_for_prompt: Boolean indicating whether to wait for the
+                command prompt to be sent by U-Boot. This typically occurs
+                immediately after the command has been executed.
+
+        Returns:
+            If wait_for_prompt == False:
+                Nothing.
+            Else:
+                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:
+                cmd += '\n'
+            while cmd:
+                # Limit max outstanding data, so UART FIFOs don't overflow
+                chunk = cmd[:self.max_fifo_fill]
+                cmd = cmd[self.max_fifo_fill:]
+                self.p.send(chunk)
+                if not wait_for_echo:
+                    continue
+                chunk = re.escape(chunk)
+                chunk = chunk.replace('\\\n', '[\r\n]')
+                m = self.p.expect([chunk] + bad_patterns)
+                if m != 0:
+                    self.at_prompt = False
+                    raise Exception('Bad pattern found on console: ' +
+                                    bad_pattern_ids[m - 1])
+            if not wait_for_prompt:
+                return
+            m = self.p.expect([self.prompt_escaped] + bad_patterns)
+            if m != 0:
+                self.at_prompt = False
+                raise Exception('Bad pattern found on console: ' +
+                                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
+            # indentation.
+            return self.p.before.strip('\r\n')
+        except Exception as ex:
+            self.log.error(str(ex))
+            self.cleanup_spawn()
+            raise
+
+    def ctrlc(self):
+        '''Send a CTRL-C character to U-Boot.
+
+        This is useful in order to stop execution of long-running synchronous
+        commands such as "ums".
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.run_command(chr(3), wait_for_echo=False, send_nl=False)
+
+    def ensure_spawned(self):
+        '''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.
+
+        This is an internal function and should not be called directly.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        if self.p:
+            return
+        try:
+            self.at_prompt = False
+            self.log.action('Starting U-Boot')
+            self.p = self.get_spawn()
+            # Real targets can take a long time to scroll large amounts of
+            # text if LCD is enabled. This value may need tweaking in the
+            # future, possibly per-test to be optimal. This works for 'help'
+            # on board 'seaboard'.
+            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:')
+            if build_idx == -1:
+                self.u_boot_version_string = self.u_boot_main_signon
+            else:
+                self.u_boot_version_string = self.u_boot_main_signon[:build_idx]
+            while True:
+                match = self.p.expect([self.prompt_escaped,
+                                       pattern_stop_autoboot_prompt])
+                if match == 1:
+                    self.p.send(chr(3)) # CTRL-C
+                    continue
+                break
+            self.at_prompt = True
+            self.at_prompt_logevt = self.logstream.logfile.cur_evt
+        except Exception as ex:
+            self.log.error(str(ex))
+            self.cleanup_spawn()
+            raise
+
+    def cleanup_spawn(self):
+        '''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.
+
+        This is an internal function and should not be called directly.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        try:
+            if self.p:
+                self.p.close()
+        except:
+            pass
+        self.p = None
+
+    def validate_version_string_in_text(self, text):
+        '''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.
+
+        Args:
+            text: The command output text to check.
+
+        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.
+
+        Create a new context manager (for use with the "with" statement) which
+        temporarily disables a particular console output error check.
+
+        Args:
+            check_type: The type of error-check to disable. Valid values may
+            be found in self.disable_check_count above.
+
+        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
new file mode 100644
index 0000000000..0ca9e7c178
--- /dev/null
+++ b/test/py/u_boot_console_exec_attach.py
@@ -0,0 +1,65 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Logic to interact with U-Boot running on real hardware, typically via a
+# physical serial port.
+
+import sys
+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
+    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.'''
+
+    def __init__(self, log, config):
+        '''Initialize a U-Boot console connection.
+
+        Args:
+            log: A multiplexed_log.Logfile instance.
+            config: A "configuration" object as defined in conftest.py.
+
+        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?).
+        # 16 is a common FIFO size.
+        # HW flow control would mean this could be infinite.
+        super(ConsoleExecAttach, self).__init__(log, config, max_fifo_fill=16)
+
+        self.log.action('Flashing U-Boot')
+        cmd = ['u-boot-test-flash', config.board_type, config.board_identity]
+        runner = self.log.get_runner(cmd[0], sys.stdout)
+        runner.run(cmd)
+        runner.close()
+
+    def get_spawn(self):
+        '''Connect to a fresh U-Boot instance.
+
+        The target board is reset, so that U-Boot begins running from scratch.
+
+        Args:
+            None.
+
+        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)
+
+        self.log.action('Resetting board')
+        cmd = ['u-boot-test-reset'] + args
+        runner = self.log.get_runner(cmd[0], sys.stdout)
+        runner.run(cmd)
+        runner.close()
+
+        return s
diff --git a/test/py/u_boot_console_sandbox.py b/test/py/u_boot_console_sandbox.py
new file mode 100644
index 0000000000..88b137e8c3
--- /dev/null
+++ b/test/py/u_boot_console_sandbox.py
@@ -0,0 +1,79 @@
+# Copyright (c) 2015 Stephen Warren
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Logic to interact with the sandbox port of U-Boot, running as a sub-process.
+
+import time
+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.'''
+
+    def __init__(self, log, config):
+        '''Initialize a U-Boot console connection.
+
+        Args:
+            log: A multiplexed_log.Logfile instance.
+            config: A "configuration" object as defined in conftest.py.
+
+        Returns:
+            Nothing.
+        '''
+
+        super(ConsoleSandbox, self).__init__(log, config, max_fifo_fill=1024)
+
+    def get_spawn(self):
+        '''Connect to a fresh U-Boot instance.
+
+        A new sandbox process is created, so that U-Boot begins running from
+        scratch.
+
+        Args:
+            None.
+
+        Returns:
+            A u_boot_spawn.Spawn object that is attached to U-Boot.
+        '''
+
+        return Spawn([self.config.build_dir + '/u-boot'])
+
+    def kill(self, sig):
+        '''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.
+
+        If required, this function waits a reasonable time for the process to
+        exit.
+
+        Args:
+            None.
+
+        Returns:
+            Boolean indicating whether the process has exited.
+        '''
+
+        p = self.p
+        self.p = None
+        for i in xrange(100):
+            ret = not p.isalive()
+            if ret:
+                break
+            time.sleep(0.1)
+        p.close()
+        return ret
diff --git a/test/py/u_boot_spawn.py b/test/py/u_boot_spawn.py
new file mode 100644
index 0000000000..1baee63df2
--- /dev/null
+++ b/test/py/u_boot_spawn.py
@@ -0,0 +1,174 @@
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Logic to spawn a sub-process and interact with its stdio.
+
+import os
+import re
+import pty
+import signal
+import select
+import time
+
+class Timeout(Exception):
+    '''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
+    sent to the process, and responses waited for.
+    '''
+
+    def __init__(self, args):
+        '''Spawn (fork/exec) the sub-process.
+
+        Args:
+            args: array of processs arguments. argv[0] is the command to execute.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.waited = False
+        self.buf = ''
+        self.logfile_read = None
+        self.before = ''
+        self.after = ''
+        self.timeout = None
+
+        (self.pid, self.fd) = pty.fork()
+        if self.pid == 0:
+            try:
+                # For some reason, SIGHUP is set to SIG_IGN at this point when
+                # run under "go" (www.go.cd). Perhaps this happens under any
+                # background (non-interactive) system?
+                signal.signal(signal.SIGHUP, signal.SIG_DFL)
+                os.execvp(args[0], args)
+            except:
+                print 'CHILD EXECEPTION:'
+                import traceback
+                traceback.print_exc()
+            finally:
+                os._exit(255)
+
+        self.poll = select.poll()
+        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.
+
+        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.
+
+        Args:
+            None.
+
+        Returns:
+            Boolean indicating whether process is alive.
+        '''
+
+        if self.waited:
+            return False
+
+        w = os.waitpid(self.pid, os.WNOHANG)
+        if w[0] == 0:
+            return True
+
+        self.waited = True
+        return False
+
+    def send(self, data):
+        '''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.
+
+        This function waits for the process to emit one pattern from the
+        supplied list of patterns, or for a timeout to occur.
+
+        Args:
+            patterns: A list of strings or regex objects that we expect to
+                see in the sub-process' stdout.
+
+        Returns:
+            The index within the patterns array of the pattern the process
+            emitted.
+
+        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])
+
+        try:
+            while True:
+                earliest_m = None
+                earliest_pi = None
+                for pi in xrange(len(patterns)):
+                    pattern = patterns[pi]
+                    m = pattern.search(self.buf)
+                    if not m:
+                        continue
+                    if earliest_m and m.start() > earliest_m.start():
+                        continue
+                    earliest_m = m
+                    earliest_pi = pi
+                if earliest_m:
+                    pos = earliest_m.start()
+                    posafter = earliest_m.end() + 1
+                    self.before = self.buf[:pos]
+                    self.after = self.buf[pos:posafter]
+                    self.buf = self.buf[posafter:]
+                    return earliest_pi
+                events = self.poll.poll(self.timeout)
+                if not events:
+                    raise Timeout()
+                c = os.read(self.fd, 1024)
+                if not c:
+                    raise EOFError()
+                if self.logfile_read:
+                    self.logfile_read.write(c)
+                self.buf += c
+        finally:
+            if self.logfile_read:
+                self.logfile_read.flush()
+
+    def close(self):
+        '''Close the stdio connection to the sub-process.
+
+        This also waits a reasonable time for the sub-process to stop running.
+
+        Args:
+            None.
+
+        Returns:
+            Nothing.
+        '''
+
+        os.close(self.fd)
+        for i in xrange(100):
+            if not self.isalive():
+                break
+            time.sleep(0.1)