diff --git a/docs/dev/how_to.rst b/docs/dev/how_to.rst index ff078fce911b1..dcf8df2331eb2 100644 --- a/docs/dev/how_to.rst +++ b/docs/dev/how_to.rst @@ -29,3 +29,4 @@ various areas of the TVM stack. relay_add_pass relay_bring_your_own_codegen codebase_walkthrough + pytest_target_parametrization diff --git a/docs/dev/pytest_target_parametrization.rst b/docs/dev/pytest_target_parametrization.rst new file mode 100644 index 0000000000000..55c4d65a7c74c --- /dev/null +++ b/docs/dev/pytest_target_parametrization.rst @@ -0,0 +1,244 @@ +Python Target Parametrization +============================= + +Summary +------- + +A single python function in the test suite can expand to several +parametrized unit tests, each of which tests a single target device. +In order for a test to be run, all of the following must be true. + +- The test exists in a file or directory that has been passed to + `pytest`. + +- The pytest marks applied to the function, either explicitly or + through target parametrization, must be compatible with the + expression passed to pytest's `-m` argument. + +- For parametrized tests using the `target` fixture, the target must + appear in the environment variable `TVM_TEST_TARGETS`. + +- For parametrized tests using the `target` fixture, the build + configuration in `config.cmake` must enable the corresponding + runtime. + +Unit-Test File Contents +----------------------- + +.. _pytest-marks: https://docs.pytest.org/en/6.2.x/mark.html + +Each test file has one or more test functions. The test functions can +be decorated with `pytest marks `_ to include metadata. +The most frequently applied marks are as follows. + +- ``@pytest.mark.gpu`` - Tags a function as using GPU + capabilities. This has no effect on its own, but can be paired with + command-line arguments ``-m gpu`` or ``-m 'not gpu'`` to restrict + which tests pytest will executed. Typically not called on its own. + +- ``@tvm.testing.uses_gpu`` - Applies ``@pytest.mark.gpu``. Needed + only for tests that explicitly loop over + ``tvm.testing.enabled_targets()``. + +- ``@tvm.testing.requires_gpu`` - Applies ``@tvm.testing.uses_gpu``, + and additionally marks that the test should be skipped + (``@pytest.mark.skipif``) entirely if no GPU is present. + +- ``@tvfm.testing.requires_RUNTIME`` - Several decorators + (e.g. ``@tvm.testing.requires_cuda``), each of which skips a test if + the specified runtime cannot be used. A runtime cannot be used if it + is disabled in the ``config.cmake``, or if a compatible device is + not present. For runtimes that use the GPU, this includes + ``@tvm.testing.requires_gpu``. + +A single test can loop over ``tvm.testing.enabled_targets()`` to +validate all enabled targets, based on the environment variable +``TVM_TEST_TARGETS``, the build configuration, and the physical +hardware present. Most current tests use this style, but it is not +recommended for new tests. The pytest output for this style silently +skips runtimes that are disabled in ``config.cmake``, or do not have a +device on which they can run. In addition, the test halts on the +first target to fail, which is ambiguous as to whether the error +occurs on a particular target, or on every target. + +.. code-block:: python + + # Old style, not recommend anymore + def test_function(): + for target,dev in tvm.testing.enabled_targets(): + # Test code goes here + +The recommended method to run a test on multiple targets is by +parametrizing the test. This can be done explicitly for a fixed list +of targets by decorating with +``@tvm.testing.parametrize_targets('target_1', 'target_2', ...)``, and +accepting ``target`` or ``dev`` as function arguments. The function will +be run once for each target listed, and the success/failure of each +target is reported separately. Each test run is decorated with the +``@tvm.testing.requires_RUNTIME`` that corresponds to the target being +used. As a result, if a target is disabled in ``config.cmake`` or does +not have appropriate hardware to run, it will be explicitly listed as +skipped. + +.. code-block:: python + + # New style, explicit listing of targets to use. + @tvm.testing.parametrize_target('llvm', 'cuda') + def test_function(target, dev): + # Test code goes here + +For tests that should run correctly on all targets, the decorator can +be omitted. Any test that accepts a ``target`` or ``dev`` argument +will automatically be parametrized over all targets specified in +``TVM_TEST_TARGETS``. The parametrization provides the same +pass/fail/skipped report for each target, while allowing the test +suite to be easily extended to cover additional targets. + +.. code-block:: python + + # New style, implicitly parametrized to run on all + # targets in environment variable TVM_TEST_TARGETS + def test_function(target, dev): + # Test code goes here + +The ``@tvm.testing.parametrize_targets`` can also be used as a bare +decorator to explicitly draw attention to the parametrization, but has +no additional effect. + +.. code-block:: python + + # New style, explicitly parametrized to run on all + # targets in environment variable TVM_TEST_TARGETS + @tvm.testing.parametrize_targets + def test_function(target, dev): + # Test code goes here + + +Specific targets can be excluded or marked as expected to fail using +the `@tvm.testing.exclude_targets` or +`@tvm.testing.known_failing_targets` decorators. For more information +on their intended use cases, please see their docstrings. + +Lastly, in some cases it may be necessary to parametrize across +multiple parameters. For instance, there may be target-specific +implementations that should be tested, where some targets have more +than one implementation. These can be done by explicitly +parametrizing over tuples of arguments, such as shown below. In these +cases, only the explicitly listed targets will run, but they will +still have the appropriate `@tvm.testing.requires_RUNTIME` mark +applied to them. + +.. code-block:: python + + @pytest.mark.parametrize('target,impl', [ + ('llvm', cpu_implementation), + ('cuda', gpu_implementation_small_batch), + ('cuda', gpu_implementation_large_batch), + ]) + def test_function(target, dev, impl): + # Test code goes here + +Running locally +--------------- + +To run the python unit-tests locally, use the command ``pytest`` in +the ``${TVM_HOME}`` directory. + +- Environment variables + - ``TVM_TEST_TARGETS`` should be a semicolon-separated list of + targets to run. If unset, will default to the targets defined in + ``tvm.testing.DEFAULT_TEST_TARGETS``. + + Note: If ``TVM_TEST_TARGETS`` does not contain any targets that + are both enabled, and have an accessible device of that type, + then the tests will fall back to running on the ``llvm`` target + only. + + - ``TVM_LIBRARY_PATH`` should be a path to the ``libtvm.so`` + library. This can be used, for example, to run tests using a + debug build. If unset, will search for ``libtvm.so`` relative to + the TVM source directory. + +- Command-line arguments + + - Passing a path to a folder or file will run only the unit tests + in that folder or file. This can be useful, for example, to + avoid running tests located in ``tests/python/frontend`` on a + system without a specific frontend installed. + + - The ``-m`` argument only runs unit tests that are tagged with a + specific pytest marker. The most frequent usage is to use ``m + gpu`` to run only tests that are marked with + ``@pytest.mark.gpu`` and use a GPU to run. It can also be used + to run only tests that do not use a GPU, by passing ``m 'not + gpu'``. + + Note: This filtering takes place after the selection of targets + based on the ``TVM_TEST_TARGETS`` environment variable. Even if + ``-m gpu`` is specified, if ``TVM_TEST_TARGETS`` does not + contain GPU targets, no GPU tests will be run. + +Running in local docker container +--------------------------------- + +.. _tlcpack: https://hub.docker.com/u/tlcpack + +The ``docker/bash.sh`` script can be used to run unit tests inside the +same docker image as is used by the CI. The first argument should +specify which docker image to run (e.g. ``docker/bash.sh ci_gpu``). +Allowed image names are defined at the top of the Jenkinsfile located +in the TVM source directory, and map to images at `tlcpack`_. + +If no additional arguments are given, the docker image will be loaded +with an interactive bash session. If a script is passed as an +optional argument (e.g. ``docker/bash.sh ci_gpu tests/scripts/task_python_unittest.sh``), then that script will be +executed inside the docker image. + +Note: The docker images contain all system dependencies, but do not +include the ``build/config.cmake`` configuration file for those +systems. The TVM source directory is used as the home directory of +the docker image, and so this will default to using the same +config/build directories as the local config. One solution is to +maintain separate ``build_local`` and ``build_docker`` directories, +and make a symlink from ``build`` to the appropriate folder when +entering/exiting docker. + +Running in CI +------------- + +Everything in the CI starts from the task definitions present in the +Jenkinsfile. This includes defining which docker image gets used, +what the compile-time configuration is, and which tests are included +in which stages. + +- Docker images + + Each task of the Jenkinsfile (e.g. 'BUILD: CPU') makes calls to + ``docker/bash.sh``. The argument following the call to + docker/bash.sh defines the docker image in CI, just as it does + locally. + +- Compile-time configuration + + The docker image does not have the ``config.cmake`` file built into + it, so this is the first step in each of the ``BUILD`` tasks. This + is done using the ``tests/scripts/task_config_build_*.sh`` scripts. + Which script is used depends on the build being tested, and is + specified in the Jenkinsfile. + + Each ``BUILD`` task concludes by packing a library for use in later + tests. + +- Which tests run + + The ``Unit Test`` and ``Integration Test`` stages of the Jenkinsfile + determine how ``pytest`` is called. Each task starts by unpacking a + compiled library that was previous compiled in the ``BUILD`` stage, + then runs a test script + (e.g. ``tests/script/task_python_unittest.sh``). These scripts set + the files/folders and command-line options that are passed to + ``pytest``. + + Several of these scripts include the ``-m gpu`` option, which + restricts the tests to only run tests that include the + ``@pytest.mark.gpu`` mark.