lit - LLVM Integrated Tester

.. program:: lit

SYNOPSIS

:program:lit [options] [tests]

DESCRIPTION

:program:lit is a portable tool for executing LLVM and Clang style test suites, summarizing their results, and providing indication of failures. :program:lit is designed to be a lightweight testing tool with as simple a user interface as possible.

:program:lit should be run with one or more tests to run specified on the command line. Tests can be either individual test files or directories to search for tests (see :ref:test-discovery).

Each specified test will be executed (potentially concurrently) and once all tests have been run :program:lit will print summary information on the number of tests which passed or failed (see :ref:test-status-results). The :program:lit program will execute with a non-zero exit code if any tests fail.

By default :program:lit will use a succinct progress display and will only print summary information for test failures. See :ref:output-options for options controlling the :program:lit progress display and output.

:program:lit also includes a number of options for controlling how tests are executed (specific features may depend on the particular test format). See :ref:execution-options for more information.

Finally, :program:lit also supports additional options for only running a subset of the options specified on the command line, see :ref:selection-options for more information.

:program:lit parses options from the environment variable LIT_OPTS after parsing options from the command line. LIT_OPTS is primarily useful for supplementing or overriding the command-line options supplied to :program:lit by check targets defined by a project's build system.

:program:lit can also read options from response files which are specified as inputs using the @path/to/file.rsp syntax.

Users interested in the :program:lit architecture or designing a :program:lit testing implementation should see :ref:lit-infrastructure.

GENERAL OPTIONS

.. option:: -h, --help

Show the :program:lit help message.

.. option:: -j N, --workers=N

Run N tests in parallel. By default, this is automatically chosen to match the number of detected available CPUs.

.. option:: --config-prefix=NAME

Search for :file:{NAME}.cfg and :file:{NAME}.site.cfg when searching for test suites, instead of :file:lit.cfg and :file:lit.site.cfg.

.. option:: -D NAME[=VALUE], --param NAME[=VALUE]

Add a user defined parameter NAME with the given VALUE (or the empty string if not given). The meaning and use of these parameters is test suite dependent.

.. _output-options:

OUTPUT OPTIONS

.. option:: -q, --quiet

Suppress any output except for test failures.

.. option:: -s, --succinct

Show less output, for example don't show information on tests that pass. Also show a progress bar, unless --no-progress-bar is specified.

.. option:: -v, --verbose

Show more information on test failures, for example the entire test output instead of just the test result.

.. option:: -vv, --echo-all-commands

Echo all commands to stdout, as they are being executed. This can be valuable for debugging test failures, as the last echoed command will be the one which has failed. :program:lit normally inserts a no-op command (: in the case of bash) with argument 'RUN: at line N' before each command pipeline, and this option also causes those no-op commands to be echoed to stdout to help you locate the source line of the failed command. This option implies --verbose.

.. option:: -a, --show-all

Show more information about all tests, for example the entire test commandline and output.

.. option:: --no-progress-bar

Do not use curses based progress bar.

.. option:: --show-unsupported

Show the names of unsupported tests.

.. option:: --show-xfail

Show the names of tests that were expected to fail.

.. _execution-options:

EXECUTION OPTIONS

.. option:: --path=PATH

Specify an additional PATH to use when searching for executables in tests.

.. option:: --vg

Run individual tests under valgrind (using the memcheck tool). The --error-exitcode argument for valgrind is used so that valgrind failures will cause the program to exit with a non-zero status.

When this option is enabled, :program:lit will also automatically provide a "valgrind" feature that can be used to conditionally disable (or expect failure in) certain tests.

.. option:: --vg-arg=ARG

When :option:--vg is used, specify an additional argument to pass to :program:valgrind itself.

.. option:: --vg-leak

When :option:--vg is used, enable memory leak checks. When this option is enabled, :program:lit will also automatically provide a "vg_leak" feature that can be used to conditionally disable (or expect failure in) certain tests.

.. option:: --time-tests

Track the wall time individual tests take to execute and includes the results in the summary output. This is useful for determining which tests in a test suite take the most time to execute.

.. option:: --ignore-fail

Exit with status zero even if some tests fail.

.. option:: --no-indirectly-run-check

Do not error if a test would not be run if the user had specified the containing directory instead of naming the test directly.

.. _selection-options:

SELECTION OPTIONS

By default, lit will run failing tests first, then run tests in descending execution time order to optimize concurrency. The execution order can be changed using the :option:--order option.

The timing data is stored in the test_exec_root in a file named .lit_test_times.txt. If this file does not exist, then lit checks the test_source_root for the file to optionally accelerate clean builds.

.. option:: --shuffle

Run the tests in a random order, not failing/slowest first. Deprecated, use :option:--order instead.

.. option:: --max-failures N

Stop execution after the given number N of failures. An integer argument should be passed on the command line prior to execution.

.. option:: --max-tests=N

Run at most N tests and then terminate.

.. option:: --max-time=N

Spend at most N seconds (approximately) running tests and then terminate. Note that this is not an alias for :option:--timeout; the two are different kinds of maximums.

.. option:: --num-shards=M

Divide the set of selected tests into M equal-sized subsets or "shards", and run only one of them. Must be used with the --run-shard=N option, which selects the shard to run. The environment variable LIT_NUM_SHARDS can also be used in place of this option. These two options provide a coarse mechanism for partitioning large testsuites, for parallel execution on separate machines (say in a large testing farm).

.. option:: --order={lexical,random,smart}

Define the order in which tests are run. The supported values are:

• lexical - tests will be run in lexical order according to the test file path. This option is useful when predictable test order is desired.

• random - tests will be run in random order.

• smart - tests that failed previously will be run first, then the remaining tests, all in descending execution time order. This is the default as it optimizes concurrency.

.. option:: --run-shard=N

Select which shard to run, assuming the --num-shards=M option was provided. The two options must be used together, and the value of N must be in the range 1..M. The environment variable LIT_RUN_SHARD can also be used in place of this option.

.. option:: --timeout=N

Spend at most N seconds (approximately) running each individual test. 0 means no time limit, and 0 is the default. Note that this is not an alias for :option:--max-time; the two are different kinds of maximums.

.. option:: --filter=REGEXP

Run only those tests whose name matches the regular expression specified in REGEXP. The environment variable LIT_FILTER can be also used in place of this option, which is especially useful in environments where the call to lit is issued indirectly.

.. option:: --filter-out=REGEXP

Filter out those tests whose name matches the regular expression specified in REGEXP. The environment variable LIT_FILTER_OUT can be also used in place of this option, which is especially useful in environments where the call to lit is issued indirectly.

.. option:: --xfail=LIST

Treat those tests whose name is in the semicolon separated list LIST as XFAIL. This can be helpful when one does not want to modify the test suite. The environment variable LIT_XFAIL can be also used in place of this option, which is especially useful in environments where the call to lit is issued indirectly.

A test name can specified as a file name relative to the test suite directory. For example:

.. code-block:: none

LIT_XFAIL="affinity/kmp-hw-subset.c;offloading/memory_manager.cpp"

In this case, all of the following tests are treated as XFAIL:

.. code-block:: none

libomp :: affinity/kmp-hw-subset.c
libomptarget :: nvptx64-nvidia-cuda :: offloading/memory_manager.cpp
libomptarget :: x86_64-pc-linux-gnu :: offloading/memory_manager.cpp

Alternatively, a test name can be specified as the full test name reported in LIT output. For example, we can adjust the previous example not to treat the nvptx64-nvidia-cuda version of offloading/memory_manager.cpp as XFAIL:

.. code-block:: none

LIT_XFAIL="affinity/kmp-hw-subset.c;libomptarget :: x86_64-pc-linux-gnu :: offloading/memory_manager.cpp"

.. option:: --xfail-not=LIST

Do not treat the specified tests as XFAIL. The environment variable LIT_XFAIL_NOT can also be used in place of this option. The syntax is the same as for :option:--xfail and LIT_XFAIL. :option:--xfail-not and LIT_XFAIL_NOT always override all other XFAIL specifications, including an :option:--xfail appearing later on the command line. The primary purpose is to suppress an XPASS result without modifying a test case that uses the XFAIL directive.

ADDITIONAL OPTIONS

.. option:: --debug

Run :program:lit in debug mode, for debugging configuration issues and :program:lit itself.

.. option:: --show-suites

List the discovered test suites and exit.

.. option:: --show-tests

List all of the discovered tests and exit.

EXIT STATUS

:program:lit will exit with an exit code of 1 if there are any FAIL or XPASS results. Otherwise, it will exit with the status 0. Other exit codes are used for non-test related failures (for example a user error or an internal program error).

.. _test-discovery:

TEST DISCOVERY

The inputs passed to :program:lit can be either individual tests, or entire directories or hierarchies of tests to run. When :program:lit starts up, the first thing it does is convert the inputs into a complete list of tests to run as part of test discovery.

In the :program:lit model, every test must exist inside some test suite. :program:lit resolves the inputs specified on the command line to test suites by searching upwards from the input path until it finds a :file:lit.cfg or :file:lit.site.cfg file. These files serve as both a marker of test suites and as configuration files which :program:lit loads in order to understand how to find and run the tests inside the test suite.

Once :program:lit has mapped the inputs into test suites it traverses the list of inputs adding tests for individual files and recursively searching for tests in directories.

This behavior makes it easy to specify a subset of tests to run, while still allowing the test suite configuration to control exactly how tests are interpreted. In addition, :program:lit always identifies tests by the test suite they are in, and their relative path inside the test suite. For appropriately configured projects, this allows :program:lit to provide convenient and flexible support for out-of-tree builds.

.. _test-status-results:

TEST STATUS RESULTS

Each test ultimately produces one of the following eight results:

PASS

The test succeeded.

FLAKYPASS

The test succeeded after being re-run more than once. This only applies to tests containing an ALLOW_RETRIES: annotation.

XFAIL

The test failed, but that is expected. This is used for test formats which allow specifying that a test does not currently work, but wish to leave it in the test suite.

XPASS

The test succeeded, but it was expected to fail. This is used for tests which were specified as expected to fail, but are now succeeding (generally because the feature they test was broken and has been fixed).

FAIL

The test failed.

UNRESOLVED

The test result could not be determined. For example, this occurs when the test could not be run, the test itself is invalid, or the test was interrupted.

UNSUPPORTED

The test is not supported in this environment. This is used by test formats which can report unsupported tests.

TIMEOUT

The test was run, but it timed out before it was able to complete. This is considered a failure.

Depending on the test format tests may produce additional information about their status (generally only for failures). See the :ref:output-options section for more information.

.. _lit-infrastructure:

LIT INFRASTRUCTURE

This section describes the :program:lit testing architecture for users interested in creating a new :program:lit testing implementation, or extending an existing one.

:program:lit proper is primarily an infrastructure for discovering and running arbitrary tests, and to expose a single convenient interface to these tests. :program:lit itself doesn't know how to run tests, rather this logic is defined by test suites.

TEST SUITES

As described in :ref:`test-discovery`, tests are always located inside a *test
suite*.  Test suites serve to define the format of the tests they contain, the
logic for finding those tests, and any additional information to run the tests.

:program:`lit` identifies test suites as directories containing ``lit.cfg`` or
``lit.site.cfg`` files (see also :option:`--config-prefix`).  Test suites are
initially discovered by recursively searching up the directory hierarchy for
all the input files passed on the command line.  You can use
:option:`--show-suites` to display the discovered test suites at startup.

Once a test suite is discovered, its config file is loaded.  Config files
themselves are Python modules which will be executed.  When the config file is
executed, two important global variables are predefined:

**lit_config**

 The global **lit** configuration object (a *LitConfig* instance), which defines
 the builtin test formats, global configuration parameters, and other helper
 routines for implementing test configurations.

**config**

 This is the config object (a *TestingConfig* instance) for the test suite,
 which the config file is expected to populate.  The following variables are also
 available on the *config* object, some of which must be set by the config and
 others are optional or predefined:

 **name** *[required]* The name of the test suite, for use in reports and
 diagnostics.

 **test_format** *[required]* The test format object which will be used to
 discover and run tests in the test suite.  Generally this will be a builtin test
 format available from the *lit.formats* module.

 **test_source_root** The filesystem path to the test suite root.  For out-of-dir
 builds this is the directory that will be scanned for tests.

 **test_exec_root** For out-of-dir builds, the path to the test suite root inside
 the object directory.  This is where tests will be run and temporary output files
 placed.

 **environment** A dictionary representing the environment to use when executing
 tests in the suite.

 **standalone_tests** When true, mark a directory with tests expected to be run
 standalone. Test discovery is disabled for that directory and
 *--no-indirectly-run-check* is in effect. *lit.suffixes* and *lit.excludes*
 must be empty when this variable is true.

 **suffixes** For **lit** test formats which scan directories for tests, this
 variable is a list of suffixes to identify test files.  Used by: *ShTest*.

 **substitutions** For **lit** test formats which substitute variables into a test
 script, the list of substitutions to perform.  Used by: *ShTest*.

 **unsupported** Mark an unsupported directory, all tests within it will be
 reported as unsupported.  Used by: *ShTest*.

 **parent** The parent configuration, this is the config object for the directory
 containing the test suite, or None.

 **root** The root configuration.  This is the top-most :program:`lit` configuration in
 the project.

 **pipefail** Normally a test using a shell pipe fails if any of the commands
 on the pipe fail. If this is not desired, setting this variable to false
 makes the test fail only if the last command in the pipe fails.

 **available_features** A set of features that can be used in `XFAIL`,
 `REQUIRES`, and `UNSUPPORTED` directives.

TEST DISCOVERY

Once test suites are located, :program:lit recursively traverses the source directory (following test_source_root) looking for tests. When :program:lit enters a sub-directory, it first checks to see if a nested test suite is defined in that directory. If so, it loads that test suite recursively, otherwise it instantiates a local test config for the directory (see :ref:local-configuration-files).

Tests are identified by the test suite they are contained within, and the relative path inside that suite. Note that the relative path may not refer to an actual file on disk; some test formats (such as GoogleTest) define "virtual tests" which have a path that contains both the path to the actual test file and a subpath to identify the virtual test.

.. _local-configuration-files:

LOCAL CONFIGURATION FILES

When :program:`lit` loads a subdirectory in a test suite, it instantiates a
local test configuration by cloning the configuration for the parent directory
--- the root of this configuration chain will always be a test suite.  Once the
test configuration is cloned :program:`lit` checks for a *lit.local.cfg* file
in the subdirectory.  If present, this file will be loaded and can be used to
specialize the configuration for each individual directory.  This facility can
be used to define subdirectories of optional tests, or to change other
configuration parameters --- for example, to change the test format, or the
suffixes which identify test files.

SUBSTITUTIONS
~~~~~~~~~~~~~

:program:`lit` allows patterns to be substituted inside RUN commands. It also
provides the following base set of substitutions, which are defined in
TestRunner.py:

 ======================= ==============
  Macro                   Substitution
 ======================= ==============
 %s                      source path (path to the file currently being run)
 %S                      source dir (directory of the file currently being run)
 %p                      same as %S
 %{pathsep}              path separator
 %{fs-src-root}          root component of file system paths pointing to the LLVM checkout
 %{fs-tmp-root}          root component of file system paths pointing to the test's temporary directory
 %{fs-sep}               file system path separator
 %t                      temporary file name unique to the test
 %basename_t             The last path component of %t but without the ``.tmp`` extension
 %T                      parent directory of %t (not unique, deprecated, do not use)
 %%                      %
 %/s                     %s but ``\`` is replaced by ``/``
 %/S                     %S but ``\`` is replaced by ``/``
 %/p                     %p but ``\`` is replaced by ``/``
 %/t                     %t but ``\`` is replaced by ``/``
 %/T                     %T but ``\`` is replaced by ``/``
 %{/s:regex_replacement} %/s but escaped for use in the replacement of a ``s@@@`` command in sed
 %{/S:regex_replacement} %/S but escaped for use in the replacement of a ``s@@@`` command in sed
 %{/p:regex_replacement} %/p but escaped for use in the replacement of a ``s@@@`` command in sed
 %{/t:regex_replacement} %/t but escaped for use in the replacement of a ``s@@@`` command in sed
 %{/T:regex_replacement} %/T but escaped for use in the replacement of a ``s@@@`` command in sed
 %:s                     On Windows, %/s but a ``:`` is removed if its the second character.
                         Otherwise, %s but with a single leading ``/`` removed.
 %:S                     On Windows, %/S but a ``:`` is removed if its the second character.
                         Otherwise, %S but with a single leading ``/`` removed.
 %:p                     On Windows, %/p but a ``:`` is removed if its the second character.
                         Otherwise, %p but with a single leading ``/`` removed.
 %:t                     On Windows, %/t but a ``:`` is removed if its the second character.
                         Otherwise, %t but with a single leading ``/`` removed.
 %:T                     On Windows, %/T but a ``:`` is removed if its the second character.
                         Otherwise, %T but with a single leading ``/`` removed.
 ======================= ==============

Other substitutions are provided that are variations on this base set and
further substitution patterns can be defined by each test module. See the
modules :ref:`local-configuration-files`.

By default, substitutions are expanded exactly once, so that if e.g. a
substitution ``%build`` is defined in top of another substitution ``%cxx``,
``%build`` will expand to ``%cxx`` textually, not to what ``%cxx`` expands to.
However, if the ``recursiveExpansionLimit`` property of the ``TestingConfig``
is set to a non-negative integer, substitutions will be expanded recursively
until that limit is reached. It is an error if the limit is reached and
expanding substitutions again would yield a different result.

More detailed information on substitutions can be found in the
:doc:`../TestingGuide`.

TEST RUN OUTPUT FORMAT
~~~~~~~~~~~~~~~~~~~~~~

The :program:`lit` output for a test run conforms to the following schema, in
both short and verbose modes (although in short mode no PASS lines will be
shown).  This schema has been chosen to be relatively easy to reliably parse by
a machine (for example in buildbot log scraping), and for other tools to
generate.

Each test result is expected to appear on a line that matches:

.. code-block:: none

  <result code>: <test name> (<progress info>)

where ``<result-code>`` is a standard test result such as PASS, FAIL, XFAIL,
XPASS, UNRESOLVED, or UNSUPPORTED.  The performance result codes of IMPROVED and
REGRESSED are also allowed.

The ``<test name>`` field can consist of an arbitrary string containing no
newline.

The ``<progress info>`` field can be used to report progress information such
as (1/300) or can be empty, but even when empty the parentheses are required.

Each test result may include additional (multiline) log information in the
following format:

.. code-block:: none

  <log delineator> TEST '(<test name>)' <trailing delineator>
  ... log message ...
  <log delineator>

where ``<test name>`` should be the name of a preceding reported test, ``<log
delineator>`` is a string of "*" characters *at least* four characters long
(the recommended length is 20), and ``<trailing delineator>`` is an arbitrary
(unparsed) string.

The following is an example of a test run output which consists of four tests A,
B, C, and D, and a log message for the failing test C:

.. code-block:: none

  PASS: A (1 of 4)
  PASS: B (2 of 4)
  FAIL: C (3 of 4)
  ******************** TEST 'C' FAILED ********************
  Test 'C' failed as a result of exit code 1.
  ********************
  PASS: D (4 of 4)

LIT EXAMPLE TESTS
~~~~~~~~~~~~~~~~~

The :program:`lit` distribution contains several example implementations of
test suites in the *ExampleTests* directory.

SEE ALSO
--------

valgrind(1)