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![Heinrich Schuchardt](/assets/img/avatar_default.png)
We already can let a Python test depend on a build option being set via @pytest.mark.buildconfigspec(). It may be necessary to let a test depend on a build option *not* being set. So let's introduce @pytest.mark.notbuildconfigspec for this purpose. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
366 lines
16 KiB
Markdown
366 lines
16 KiB
Markdown
# U-Boot pytest suite
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## Introduction
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This tool aims to test U-Boot by executing U-Boot shell commands using the
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console interface. A single top-level script exists to execute or attach to the
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U-Boot console, run the entire script of tests against it, and summarize the
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results. Advantages of this approach are:
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- Testing is performed in the same way a user or script would interact with
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U-Boot; there can be no disconnect.
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- There is no need to write or embed test-related code into U-Boot itself.
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It is asserted that writing test-related code in Python is simpler and more
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flexible than writing it all in C.
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- It is reasonably simple to interact with U-Boot in this way.
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## Requirements
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The test suite is implemented using pytest. Interaction with the U-Boot console
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involves executing some binary and interacting with its stdin/stdout. You will
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need to implement various "hook" scripts that are called by the test suite at
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the appropriate time.
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On Debian or Debian-like distributions, the following packages are required.
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Some packages are required to execute any test, and others only for specific
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tests. Similar package names should exist in other distributions.
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| Package | Version tested (Ubuntu 14.04) |
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| -------------- | ----------------------------- |
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| python | 2.7.5-5ubuntu3 |
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| python-pytest | 2.5.1-1 |
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| python-subunit | - |
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| gdisk | 0.8.8-1ubuntu0.1 |
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| dfu-util | 0.5-1 |
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| dtc | 1.4.0+dfsg-1 |
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| openssl | 1.0.1f-1ubuntu2.22 |
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The test script supports either:
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- Executing a sandbox port of U-Boot on the local machine as a sub-process,
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and interacting with it over stdin/stdout.
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- Executing an external "hook" scripts to flash a U-Boot binary onto a
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physical board, attach to the board's console stream, and reset the board.
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Further details are described later.
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### Using `virtualenv` to provide requirements
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Older distributions (e.g. Ubuntu 10.04) may not provide all the required
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packages, or may provide versions that are too old to run the test suite. One
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can use the Python `virtualenv` script to locally install more up-to-date
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versions of the required packages without interfering with the OS installation.
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For example:
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```bash
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$ cd /path/to/u-boot
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$ sudo apt-get install python python-virtualenv
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$ virtualenv venv
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$ . ./venv/bin/activate
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$ pip install pytest
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```
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## Testing sandbox
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To run the testsuite on the sandbox port (U-Boot built as a native user-space
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application), simply execute:
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```
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./test/py/test.py --bd sandbox --build
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```
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The `--bd` option tells the test suite which board type is being tested. This
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lets the test suite know which features the board has, and hence exactly what
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can be tested.
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The `--build` option tells U-Boot to compile U-Boot. Alternatively, you may
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omit this option and build U-Boot yourself, in whatever way you choose, before
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running the test script.
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The test script will attach to U-Boot, execute all valid tests for the board,
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then print a summary of the test process. A complete log of the test session
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will be written to `${build_dir}/test-log.html`. This is best viewed in a web
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browser, but may be read directly as plain text, perhaps with the aid of the
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`html2text` utility.
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### Testing under a debugger
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If you need to run sandbox under a debugger, you may pass the command-line
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option `--gdbserver COMM`. This causes two things to happens:
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- Instead of running U-Boot directly, it will be run under gdbserver, with
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debug communication via the channel `COMM`. You can attach a debugger to the
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sandbox process in order to debug it. See `man gdbserver` and the example
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below for details of valid values for `COMM`.
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- All timeouts in tests are disabled, allowing U-Boot an arbitrary amount of
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time to execute commands. This is useful if U-Boot is stopped at a breakpoint
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during debugging.
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A usage example is:
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Window 1:
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```shell
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./test/py/test.py --bd sandbox --gdbserver localhost:1234
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```
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Window 2:
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```shell
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gdb ./build-sandbox/u-boot -ex 'target remote localhost:1234'
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```
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Alternatively, you could leave off the `-ex` option and type the command
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manually into gdb once it starts.
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You can use any debugger you wish, so long as it speaks the gdb remote
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protocol, or any graphical wrapper around gdb.
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Some tests deliberately cause the sandbox process to exit, e.g. to test the
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reset command, or sandbox's CTRL-C handling. When this happens, you will need
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to attach the debugger to the new sandbox instance. If these tests are not
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relevant to your debugging session, you can skip them using pytest's -k
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command-line option; see the next section.
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## Command-line options
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- `--board-type`, `--bd`, `-B` set the type of the board to be tested. For
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example, `sandbox` or `seaboard`.
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- `--board-identity`, `--id` set the identity of the board to be tested.
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This allows differentiation between multiple instances of the same type of
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physical board that are attached to the same host machine. This parameter is
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not interpreted by the test script in any way, but rather is simply passed
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to the hook scripts described below, and may be used in any site-specific
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way deemed necessary.
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- `--build` indicates that the test script should compile U-Boot itself
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before running the tests. If using this option, make sure that any
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environment variables required by the build process are already set, such as
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`$CROSS_COMPILE`.
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- `--build-dir` sets the directory containing the compiled U-Boot binaries.
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If omitted, this is `${source_dir}/build-${board_type}`.
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- `--result-dir` sets the directory to write results, such as log files,
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into. If omitted, the build directory is used.
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- `--persistent-data-dir` sets the directory used to store persistent test
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data. This is test data that may be re-used across test runs, such as file-
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system images.
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`pytest` also implements a number of its own command-line options. Commonly used
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options are mentioned below. Please see `pytest` documentation for complete
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details. Execute `py.test --version` for a brief summary. Note that U-Boot's
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test.py script passes all command-line arguments directly to `pytest` for
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processing.
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- `-k` selects which tests to run. The default is to run all known tests. This
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option takes a single argument which is used to filter test names. Simple
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logical operators are supported. For example:
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- `'ums'` runs only tests with "ums" in their name.
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- `'ut_dm'` runs only tests with "ut_dm" in their name. Note that in this
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case, "ut_dm" is a parameter to a test rather than the test name. The full
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test name is e.g. "test_ut[ut_dm_leak]".
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- `'not reset'` runs everything except tests with "reset" in their name.
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- `'ut or hush'` runs only tests with "ut" or "hush" in their name.
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- `'not (ut or hush)'` runs everything except tests with "ut" or "hush" in
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their name.
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- `-s` prevents pytest from hiding a test's stdout. This allows you to see
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U-Boot's console log in real time on pytest's stdout.
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## Testing real hardware
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The tools and techniques used to interact with real hardware will vary
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radically between different host and target systems, and the whims of the user.
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For this reason, the test suite does not attempt to directly interact with real
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hardware in any way. Rather, it executes a standardized set of "hook" scripts
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via `$PATH`. These scripts implement certain actions on behalf of the test
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suite. This keeps the test suite simple and isolated from system variances
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unrelated to U-Boot features.
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### Hook scripts
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#### Environment variables
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The following environment variables are set when running hook scripts:
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- `UBOOT_BOARD_TYPE` the board type being tested.
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- `UBOOT_BOARD_IDENTITY` the board identity being tested, or `na` if none was
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specified.
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- `UBOOT_SOURCE_DIR` the U-Boot source directory.
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- `UBOOT_TEST_PY_DIR` the full path to `test/py/` in the source directory.
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- `UBOOT_BUILD_DIR` the U-Boot build directory.
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- `UBOOT_RESULT_DIR` the test result directory.
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- `UBOOT_PERSISTENT_DATA_DIR` the test persistent data directory.
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#### `u-boot-test-console`
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This script provides access to the U-Boot console. The script's stdin/stdout
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should be connected to the board's console. This process should continue to run
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indefinitely, until killed. The test suite will run this script in parallel
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with all other hooks.
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This script may be implemented e.g. by exec()ing `cu`, `kermit`, `conmux`, etc.
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If you are able to run U-Boot under a hardware simulator such as qemu, then
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you would likely spawn that simulator from this script. However, note that
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`u-boot-test-reset` may be called multiple times per test script run, and must
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cause U-Boot to start execution from scratch each time. Hopefully your
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simulator includes a virtual reset button! If not, you can launch the
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simulator from `u-boot-test-reset` instead, while arranging for this console
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process to always communicate with the current simulator instance.
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#### `u-boot-test-flash`
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Prior to running the test suite against a board, some arrangement must be made
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so that the board executes the particular U-Boot binary to be tested. Often,
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this involves writing the U-Boot binary to the board's flash ROM. The test
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suite calls this hook script for that purpose.
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This script should perform the entire flashing process synchronously; the
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script should only exit once flashing is complete, and a board reset will
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cause the newly flashed U-Boot binary to be executed.
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It is conceivable that this script will do nothing. This might be useful in
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the following cases:
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- Some other process has already written the desired U-Boot binary into the
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board's flash prior to running the test suite.
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- The board allows U-Boot to be downloaded directly into RAM, and executed
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from there. Use of this feature will reduce wear on the board's flash, so
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may be preferable if available, and if cold boot testing of U-Boot is not
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required. If this feature is used, the `u-boot-test-reset` script should
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perform this download, since the board could conceivably be reset multiple
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times in a single test run.
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It is up to the user to determine if those situations exist, and to code this
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hook script appropriately.
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This script will typically be implemented by calling out to some SoC- or
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board-specific vendor flashing utility.
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#### `u-boot-test-reset`
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Whenever the test suite needs to reset the target board, this script is
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executed. This is guaranteed to happen at least once, prior to executing the
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first test function. If any test fails, the test infra-structure will execute
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this script again to restore U-Boot to an operational state before running the
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next test function.
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This script will likely be implemented by communicating with some form of
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relay or electronic switch attached to the board's reset signal.
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The semantics of this script require that when it is executed, U-Boot will
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start running from scratch. If the U-Boot binary to be tested has been written
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to flash, pulsing the board's reset signal is likely all this script need do.
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However, in some scenarios, this script may perform other actions. For
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example, it may call out to some SoC- or board-specific vendor utility in order
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to download the U-Boot binary directly into RAM and execute it. This would
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avoid the need for `u-boot-test-flash` to actually write U-Boot to flash, thus
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saving wear on the flash chip(s).
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#### Examples
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https://github.com/swarren/uboot-test-hooks contains some working example hook
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scripts, and may be useful as a reference when implementing hook scripts for
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your platform. These scripts are not considered part of U-Boot itself.
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### Board-type-specific configuration
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Each board has a different configuration and behaviour. Many of these
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differences can be automatically detected by parsing the `.config` file in the
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build directory. However, some differences can't yet be handled automatically.
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For each board, an optional Python module `u_boot_board_${board_type}` may exist
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to provide board-specific information to the test script. Any global value
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defined in these modules is available for use by any test function. The data
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contained in these scripts must be purely derived from U-Boot source code.
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Hence, these configuration files are part of the U-Boot source tree too.
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### Execution environment configuration
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Each user's hardware setup may enable testing different subsets of the features
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implemented by a particular board's configuration of U-Boot. For example, a
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U-Boot configuration may support USB device mode and USB Mass Storage, but this
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can only be tested if a USB cable is connected between the board and the host
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machine running the test script.
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For each board, optional Python modules `u_boot_boardenv_${board_type}` and
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`u_boot_boardenv_${board_type}_${board_identity}` may exist to provide
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board-specific and board-identity-specific information to the test script. Any
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global value defined in these modules is available for use by any test
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function. The data contained in these is specific to a particular user's
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hardware configuration. Hence, these configuration files are not part of the
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U-Boot source tree, and should be installed outside of the source tree. Users
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should set `$PYTHONPATH` prior to running the test script to allow these
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modules to be loaded.
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### Board module parameter usage
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The test scripts rely on the following variables being defined by the board
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module:
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- None at present.
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### U-Boot `.config` feature usage
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The test scripts rely on various U-Boot `.config` features, either directly in
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order to test those features, or indirectly in order to query information from
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the running U-Boot instance in order to test other features.
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One example is that testing of the `md` command requires knowledge of a RAM
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address to use for the test. This data is parsed from the output of the
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`bdinfo` command, and hence relies on CONFIG_CMD_BDI being enabled.
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For a complete list of dependencies, please search the test scripts for
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instances of:
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- `buildconfig.get(...`
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- `@pytest.mark.buildconfigspec(...`
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- `@pytest.mark.notbuildconfigspec(...`
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### Complete invocation example
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Assuming that you have installed the hook scripts into $HOME/ubtest/bin, and
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any required environment configuration Python modules into $HOME/ubtest/py,
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then you would likely invoke the test script as follows:
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If U-Boot has already been built:
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```bash
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PATH=$HOME/ubtest/bin:$PATH \
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PYTHONPATH=${HOME}/ubtest/py/${HOSTNAME}:${PYTHONPATH} \
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./test/py/test.py --bd seaboard
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```
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If you want the test script to compile U-Boot for you too, then you likely
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need to set `$CROSS_COMPILE` to allow this, and invoke the test script as
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follow:
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```bash
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CROSS_COMPILE=arm-none-eabi- \
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PATH=$HOME/ubtest/bin:$PATH \
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PYTHONPATH=${HOME}/ubtest/py/${HOSTNAME}:${PYTHONPATH} \
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./test/py/test.py --bd seaboard --build
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```
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## Writing tests
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Please refer to the pytest documentation for details of writing pytest tests.
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Details specific to the U-Boot test suite are described below.
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A test fixture named `u_boot_console` should be used by each test function. This
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provides the means to interact with the U-Boot console, and retrieve board and
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environment configuration information.
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The function `u_boot_console.run_command()` executes a shell command on the
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U-Boot console, and returns all output from that command. This allows
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validation or interpretation of the command output. This function validates
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that certain strings are not seen on the U-Boot console. These include shell
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error messages and the U-Boot sign-on message (in order to detect unexpected
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board resets). See the source of `u_boot_console_base.py` for a complete list of
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"bad" strings. Some test scenarios are expected to trigger these strings. Use
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`u_boot_console.disable_check()` to temporarily disable checking for specific
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strings. See `test_unknown_cmd.py` for an example.
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Board- and board-environment configuration values may be accessed as sub-fields
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of the `u_boot_console.config` object, for example
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`u_boot_console.config.ram_base`.
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Build configuration values (from `.config`) may be accessed via the dictionary
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`u_boot_console.config.buildconfig`, with keys equal to the Kconfig variable
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names.
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