forked from OSchip/llvm-project
415 lines
14 KiB
ReStructuredText
415 lines
14 KiB
ReStructuredText
lit - LLVM Integrated Tester
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============================
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SYNOPSIS
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--------
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:program:`lit` [*options*] [*tests*]
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DESCRIPTION
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-----------
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:program:`lit` is a portable tool for executing LLVM and Clang style test
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suites, summarizing their results, and providing indication of failures.
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:program:`lit` is designed to be a lightweight testing tool with as simple a
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user interface as possible.
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:program:`lit` should be run with one or more *tests* to run specified on the
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command line. Tests can be either individual test files or directories to
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search for tests (see :ref:`test-discovery`).
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Each specified test will be executed (potentially in parallel) and once all
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tests have been run :program:`lit` will print summary information on the number
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of tests which passed or failed (see :ref:`test-status-results`). The
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:program:`lit` program will execute with a non-zero exit code if any tests
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fail.
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By default :program:`lit` will use a succinct progress display and will only
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print summary information for test failures. See :ref:`output-options` for
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options controlling the :program:`lit` progress display and output.
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:program:`lit` also includes a number of options for controlling how tests are
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executed (specific features may depend on the particular test format). See
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:ref:`execution-options` for more information.
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Finally, :program:`lit` also supports additional options for only running a
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subset of the options specified on the command line, see
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:ref:`selection-options` for more information.
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Users interested in the :program:`lit` architecture or designing a
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:program:`lit` testing implementation should see :ref:`lit-infrastructure`.
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GENERAL OPTIONS
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---------------
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.. option:: -h, --help
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Show the :program:`lit` help message.
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.. option:: -j N, --threads=N
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Run ``N`` tests in parallel. By default, this is automatically chosen to
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match the number of detected available CPUs.
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.. option:: --config-prefix=NAME
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Search for :file:`{NAME}.cfg` and :file:`{NAME}.site.cfg` when searching for
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test suites, instead of :file:`lit.cfg` and :file:`lit.site.cfg`.
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.. option:: -D NAME, -D NAME=VALUE, --param NAME, --param NAME=VALUE
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Add a user defined parameter ``NAME`` with the given ``VALUE`` (or the empty
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string if not given). The meaning and use of these parameters is test suite
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dependent.
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.. _output-options:
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OUTPUT OPTIONS
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--------------
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.. option:: -q, --quiet
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Suppress any output except for test failures.
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.. option:: -s, --succinct
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Show less output, for example don't show information on tests that pass.
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.. option:: -v, --verbose
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Show more information on test failures, for example the entire test output
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instead of just the test result.
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.. option:: --no-progress-bar
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Do not use curses based progress bar.
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.. option:: --show-unsupported
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Show the names of unsupported tests.
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.. option:: --show-xfail
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Show the names of tests that were expected to fail.
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.. _execution-options:
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EXECUTION OPTIONS
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-----------------
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.. option:: --path=PATH
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Specify an additional ``PATH`` to use when searching for executables in tests.
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.. option:: --vg
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Run individual tests under valgrind (using the memcheck tool). The
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``--error-exitcode`` argument for valgrind is used so that valgrind failures
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will cause the program to exit with a non-zero status.
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When this option is enabled, :program:`lit` will also automatically provide a
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"``valgrind``" feature that can be used to conditionally disable (or expect
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failure in) certain tests.
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.. option:: --vg-arg=ARG
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When :option:`--vg` is used, specify an additional argument to pass to
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:program:`valgrind` itself.
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.. option:: --vg-leak
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When :option:`--vg` is used, enable memory leak checks. When this option is
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enabled, :program:`lit` will also automatically provide a "``vg_leak``"
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feature that can be used to conditionally disable (or expect failure in)
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certain tests.
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.. option:: --time-tests
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Track the wall time individual tests take to execute and includes the results
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in the summary output. This is useful for determining which tests in a test
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suite take the most time to execute. Note that this option is most useful
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with ``-j 1``.
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.. _selection-options:
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SELECTION OPTIONS
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-----------------
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.. option:: --max-tests=N
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Run at most ``N`` tests and then terminate.
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.. option:: --max-time=N
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Spend at most ``N`` seconds (approximately) running tests and then terminate.
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.. option:: --shuffle
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Run the tests in a random order.
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ADDITIONAL OPTIONS
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------------------
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.. option:: --debug
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Run :program:`lit` in debug mode, for debugging configuration issues and
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:program:`lit` itself.
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.. option:: --show-suites
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List the discovered test suites and exit.
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.. option:: --show-tests
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List all of the the discovered tests and exit.
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EXIT STATUS
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-----------
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:program:`lit` will exit with an exit code of 1 if there are any FAIL or XPASS
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results. Otherwise, it will exit with the status 0. Other exit codes are used
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for non-test related failures (for example a user error or an internal program
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error).
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.. _test-discovery:
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TEST DISCOVERY
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--------------
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The inputs passed to :program:`lit` can be either individual tests, or entire
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directories or hierarchies of tests to run. When :program:`lit` starts up, the
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first thing it does is convert the inputs into a complete list of tests to run
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as part of *test discovery*.
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In the :program:`lit` model, every test must exist inside some *test suite*.
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:program:`lit` resolves the inputs specified on the command line to test suites
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by searching upwards from the input path until it finds a :file:`lit.cfg` or
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:file:`lit.site.cfg` file. These files serve as both a marker of test suites
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and as configuration files which :program:`lit` loads in order to understand
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how to find and run the tests inside the test suite.
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Once :program:`lit` has mapped the inputs into test suites it traverses the
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list of inputs adding tests for individual files and recursively searching for
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tests in directories.
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This behavior makes it easy to specify a subset of tests to run, while still
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allowing the test suite configuration to control exactly how tests are
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interpreted. In addition, :program:`lit` always identifies tests by the test
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suite they are in, and their relative path inside the test suite. For
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appropriately configured projects, this allows :program:`lit` to provide
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convenient and flexible support for out-of-tree builds.
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.. _test-status-results:
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TEST STATUS RESULTS
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-------------------
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Each test ultimately produces one of the following six results:
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**PASS**
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The test succeeded.
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**XFAIL**
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The test failed, but that is expected. This is used for test formats which allow
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specifying that a test does not currently work, but wish to leave it in the test
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suite.
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**XPASS**
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The test succeeded, but it was expected to fail. This is used for tests which
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were specified as expected to fail, but are now succeeding (generally because
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the feature they test was broken and has been fixed).
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**FAIL**
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The test failed.
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**UNRESOLVED**
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The test result could not be determined. For example, this occurs when the test
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could not be run, the test itself is invalid, or the test was interrupted.
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**UNSUPPORTED**
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The test is not supported in this environment. This is used by test formats
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which can report unsupported tests.
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Depending on the test format tests may produce additional information about
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their status (generally only for failures). See the :ref:`output-options`
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section for more information.
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.. _lit-infrastructure:
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LIT INFRASTRUCTURE
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------------------
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This section describes the :program:`lit` testing architecture for users interested in
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creating a new :program:`lit` testing implementation, or extending an existing one.
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:program:`lit` proper is primarily an infrastructure for discovering and running
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arbitrary tests, and to expose a single convenient interface to these
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tests. :program:`lit` itself doesn't know how to run tests, rather this logic is
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defined by *test suites*.
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TEST SUITES
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~~~~~~~~~~~
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As described in :ref:`test-discovery`, tests are always located inside a *test
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suite*. Test suites serve to define the format of the tests they contain, the
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logic for finding those tests, and any additional information to run the tests.
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:program:`lit` identifies test suites as directories containing ``lit.cfg`` or
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``lit.site.cfg`` files (see also :option:`--config-prefix`). Test suites are
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initially discovered by recursively searching up the directory hierarchy for
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all the input files passed on the command line. You can use
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:option:`--show-suites` to display the discovered test suites at startup.
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Once a test suite is discovered, its config file is loaded. Config files
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themselves are Python modules which will be executed. When the config file is
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executed, two important global variables are predefined:
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**lit_config**
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The global **lit** configuration object (a *LitConfig* instance), which defines
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the builtin test formats, global configuration parameters, and other helper
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routines for implementing test configurations.
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**config**
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This is the config object (a *TestingConfig* instance) for the test suite,
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which the config file is expected to populate. The following variables are also
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available on the *config* object, some of which must be set by the config and
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others are optional or predefined:
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**name** *[required]* The name of the test suite, for use in reports and
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diagnostics.
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**test_format** *[required]* The test format object which will be used to
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discover and run tests in the test suite. Generally this will be a builtin test
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format available from the *lit.formats* module.
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**test_source_root** The filesystem path to the test suite root. For out-of-dir
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builds this is the directory that will be scanned for tests.
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**test_exec_root** For out-of-dir builds, the path to the test suite root inside
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the object directory. This is where tests will be run and temporary output files
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placed.
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**environment** A dictionary representing the environment to use when executing
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tests in the suite.
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**suffixes** For **lit** test formats which scan directories for tests, this
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variable is a list of suffixes to identify test files. Used by: *ShTest*.
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**substitutions** For **lit** test formats which substitute variables into a test
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script, the list of substitutions to perform. Used by: *ShTest*.
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**unsupported** Mark an unsupported directory, all tests within it will be
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reported as unsupported. Used by: *ShTest*.
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**parent** The parent configuration, this is the config object for the directory
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containing the test suite, or None.
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**root** The root configuration. This is the top-most :program:`lit` configuration in
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the project.
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**pipefail** Normally a test using a shell pipe fails if any of the commands
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on the pipe fail. If this is not desired, setting this variable to false
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makes the test fail only if the last command in the pipe fails.
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TEST DISCOVERY
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~~~~~~~~~~~~~~
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Once test suites are located, :program:`lit` recursively traverses the source
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directory (following *test_source_root*) looking for tests. When :program:`lit`
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enters a sub-directory, it first checks to see if a nested test suite is
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defined in that directory. If so, it loads that test suite recursively,
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otherwise it instantiates a local test config for the directory (see
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:ref:`local-configuration-files`).
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Tests are identified by the test suite they are contained within, and the
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relative path inside that suite. Note that the relative path may not refer to
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an actual file on disk; some test formats (such as *GoogleTest*) define
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"virtual tests" which have a path that contains both the path to the actual
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test file and a subpath to identify the virtual test.
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.. _local-configuration-files:
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LOCAL CONFIGURATION FILES
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~~~~~~~~~~~~~~~~~~~~~~~~~
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When :program:`lit` loads a subdirectory in a test suite, it instantiates a
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local test configuration by cloning the configuration for the parent directory
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--- the root of this configuration chain will always be a test suite. Once the
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test configuration is cloned :program:`lit` checks for a *lit.local.cfg* file
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in the subdirectory. If present, this file will be loaded and can be used to
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specialize the configuration for each individual directory. This facility can
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be used to define subdirectories of optional tests, or to change other
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configuration parameters --- for example, to change the test format, or the
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suffixes which identify test files.
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TEST RUN OUTPUT FORMAT
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~~~~~~~~~~~~~~~~~~~~~~
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The :program:`lit` output for a test run conforms to the following schema, in
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both short and verbose modes (although in short mode no PASS lines will be
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shown). This schema has been chosen to be relatively easy to reliably parse by
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a machine (for example in buildbot log scraping), and for other tools to
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generate.
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Each test result is expected to appear on a line that matches:
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.. code-block:: none
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<result code>: <test name> (<progress info>)
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where ``<result-code>`` is a standard test result such as PASS, FAIL, XFAIL,
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XPASS, UNRESOLVED, or UNSUPPORTED. The performance result codes of IMPROVED and
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REGRESSED are also allowed.
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The ``<test name>`` field can consist of an arbitrary string containing no
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newline.
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The ``<progress info>`` field can be used to report progress information such
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as (1/300) or can be empty, but even when empty the parentheses are required.
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Each test result may include additional (multiline) log information in the
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following format:
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.. code-block:: none
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<log delineator> TEST '(<test name>)' <trailing delineator>
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... log message ...
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<log delineator>
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where ``<test name>`` should be the name of a preceding reported test, ``<log
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delineator>`` is a string of "*" characters *at least* four characters long
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(the recommended length is 20), and ``<trailing delineator>`` is an arbitrary
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(unparsed) string.
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The following is an example of a test run output which consists of four tests A,
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B, C, and D, and a log message for the failing test C:
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.. code-block:: none
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PASS: A (1 of 4)
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PASS: B (2 of 4)
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FAIL: C (3 of 4)
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******************** TEST 'C' FAILED ********************
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Test 'C' failed as a result of exit code 1.
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********************
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PASS: D (4 of 4)
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LIT EXAMPLE TESTS
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~~~~~~~~~~~~~~~~~
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The :program:`lit` distribution contains several example implementations of
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test suites in the *ExampleTests* directory.
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SEE ALSO
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--------
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valgrind(1)
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