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       lit - LLVM Integrated Tester


       lit [options] [tests]


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

       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 "TEST DISCOVERY").

       Each specified test will be executed (potentially in parallel) and once
       all tests have been run lit will print summary information on the
       number of tests which passed or failed (see "TEST STATUS RESULTS"). The
       lit program will execute with a non-zero exit code if any tests fail.

       By default lit will use a succinct progress display and will only print
       summary information for test failures. See "OUTPUT OPTIONS" for options
       controlling the lit progress display and output.

       lit also includes a number of options for controlling how tests are
       exected (specific features may depend on the particular test format).
       See "EXECUTION OPTIONS" for more information.

       Finally, lit also supports additional options for only running a subset
       of the options specified on the command line, see "SELECTION OPTIONS"
       for more information.

       Users interested in the lit architecture or designing a lit testing
       implementation should see "LIT ARCHITECTURE"


       -h, --help
           Show the lit help message.

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

           Search for NAME.cfg and when searching for test
           suites, instead of lit.cfg and

       --param NAME, --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.


       -q, --quiet
           Suppress any output except for test failures.

       -s, --succinct
           Show less output, for example don't show information on tests that

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

           Do not use curses based progress bar.


           Specify an addition PATH to use when searching for executables in

           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 --vg is used, specify an additional argument to pass to
           valgrind itself.

           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. Note
           that this option is most useful with -j 1.


           Run at most N tests and then terminate.

           Spend at most N seconds (approximately) running tests and then

           Run the tests in a random order.


           Run lit in debug mode, for debugging configuration issues and lit

           List the discovered test suites as part of the standard output.

           Run Tcl scripts internally (instead of converting to shell

           Run each test N times. Currently this is primarily useful for
           timing tests, other results are not collated in any reasonable


       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
       used for non-test related failures (for example a user error or an
       internal program error).


       The inputs passed to lit can be either individual tests, or entire
       directories or hierarchies of tests to run. When 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 lit model, every test must exist inside some test suite. lit
       resolves the inputs specified on the command line to test suites by
       searching upwards from the input path until it finds a lit.cfg or file. These files serve as both a marker of test suites
       and as configuration files which lit loads in order to understand how
       to find and run the tests inside the test suite.

       Once 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, 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 lit to provide
       convenient and flexible support for out-of-tree builds.


       Each test ultimately produces one of the following six results:

           The test succeeded.

           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.

           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 feautre they test was broken and
           has been fixed).

           The test failed.

           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.

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

       Depending on the test format tests may produce additional information
       about their status (generally only for failures). See the Output
       section for more information.


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

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

       As described in "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.

       lit identifies test suites as directories containing lit.cfg or files (see also --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 --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 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.

           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

           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_src_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 places.

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

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

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

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

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

           on_clone The config is actually cloned for every subdirectory
           inside a test suite, to allow local configuration on a per-
           directory basis. The on_clone variable can be set to a Python
           function which will be called whenever a configuration is cloned
           (for a subdirectory). The function should takes three arguments:
           (1) the parent configuration, (2) the new configuration (which the
           on_clone function will generally modify), and (3) the test path to
           the new directory being scanned.

       Once test suites are located, lit recursively traverses the source
       directory (following test_src_root) looking for tests. When lit enters
       a sub-directory, it first checks to see if a nest 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

       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

       When lit loads a subdirectory in a test suite, it instantiates a local
       test configuration by cloning the configuration for the parent
       direction -- the root of this configuration chain will always be a test
       suite. Once the test configuration is cloned 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.

       The lit distribution contains several example implementations of test
       suites in the ExampleTests directory.




       Written by Daniel Dunbar and maintained by the LLVM Team