LIT(1)



LIT(1)                               LLVM                               LIT(1)

NAME
       lit - LLVM Integrated Tester

SYNOPSIS
       lit [options] [tests]

DESCRIPTION
       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 in-
       terface as possible.

       lit should be run with one or more tests to run specified on  the  com-
       mand 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 num-
       ber 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 ex-
       ecuted (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 im-
       plementation should see LIT INFRASTRUCTURE.

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

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

       --config-prefix=NAME
              Search  for  NAME.cfg  and NAME.site.cfg when searching for test
              suites, instead of lit.cfg and lit.site.cfg.

       -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 param-
              eters is test suite dependent.

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

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

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

       -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.  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  im-
              plies --verbose.

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

       --no-progress-bar
              Do not use curses based progress bar.

       --show-unsupported
              Show the names of unsupported tests.

       --show-xfail
              Show the names of tests that were expected to fail.

EXECUTION OPTIONS
       --path=PATH
              Specify an additional PATH to use when searching for executables
              in tests.

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

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

       --vg-arg=ARG
              When --vg is used, specify an additional  argument  to  pass  to
              valgrind itself.

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

       --time-tests
              Track the wall time individual tests take  to  execute  and  in-
              cludes  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.

SELECTION OPTIONS
       --max-tests=N
              Run at most N tests and then terminate.

       --max-time=N
              Spend  at  most N seconds (approximately) running tests and then
              terminate.

       --shuffle
              Run the tests in a random order.

       --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  envi-
              ronment  variable  LIT_NUM_SHARDS  can  also be used in place of
              this option. These two options provide a  coarse  mechanism  for
              paritioning large testsuites, for parallel execution on separate
              machines (say in a large testing farm).

       --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.

       --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.

ADDITIONAL OPTIONS
       --debug
              Run lit in debug mode, for debugging  configuration  issues  and
              lit itself.

       --show-suites
              List the discovered test suites and exit.

       --show-tests
              List all of the discovered tests and exit.

EXIT STATUS
       lit will exit with an exit code of 1 if there are any FAIL or XPASS re-
       sults.  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
       The inputs passed to lit can be either individual tests, or entire  di-
       rectories  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
       lit.site.cfg 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  con-
       venient and flexible support for out-of-tree builds.

TEST STATUS RESULTS
       Each test ultimately produces one of the following six results:

       PASS
          The test succeeded.

       XFAIL
          The  test  failed, but that is expected.  This is used for test for-
          mats 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 succeed-
          ing (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.

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

LIT INFRASTRUCTURE
       This  section  describes  the lit testing architecture for users inter-
       ested in creating a new lit testing implementation, or extending an ex-
       isting 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.

   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 con-
       tain, the logic for finding those tests, and any additional information
       to run the tests.

       lit  identifies  test  suites  as  directories  containing  lit.cfg  or
       lit.site.cfg files (see also --config-prefix).  Test  suites  are  ini-
       tially  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_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.

          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 lit configuration
          in the project.

          pipefail Normally a test using a shell pipe fails if any of the com-
          mands  on  the pipe fail. If this is not desired, setting this vari-
          able 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, RE-
          QUIRES, and UNSUPPORTED directives.

   TEST DISCOVERY
       Once test suites are located, lit recursively traverses the source  di-
       rectory  (following  test_source_root) looking for tests.  When lit en-
       ters 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 recur-
       sively, otherwise it instantiates a local test config for the directory
       (see 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
       When lit loads a subdirectory in a test suite, it instantiates a  local
       test  configuration  by cloning the configuration for the parent direc-
       tory -- the root of this configuration chain  will  always  be  a  test
       suite.   Once the test configuration is cloned lit checks for a lit.lo-
       cal.cfg file in the subdirectory.  If present, this file will be loaded
       and can be used to specialize the configuration for each individual di-
       rectory.  This facility can be used to  define  subdirectories  of  op-
       tional  tests, or to change other configuration parameters -- for exam-
       ple, to change the test format, or the  suffixes  which  identify  test
       files.

   PRE-DEFINED SUBSTITUTIONS
       lit  provides  various  patterns that can be used with the RUN command.
       These are defined in TestRunner.py. The base set of substitutions are:

                       +-----------+----------------------------+
                       |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             |
                       +-----------+----------------------------+
                       |%t         | temporary file name unique |
                       |           | to the test                |
                       +-----------+----------------------------+
                       |%T         | parent  directory  of   %t |
                       |           | (not  unique,  deprecated, |
                       |           | do not use)                |
                       +-----------+----------------------------+
                       |%%         | %                          |
                       +-----------+----------------------------+

       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 LOCAL CONFIGURATION FILES.

       More detailed information on substitutions can be found in the ../Test-
       ingGuide.

   TEST RUN OUTPUT FORMAT
       The 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:

          <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:

          <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 arbi-
       trary (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:

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

SEE ALSO
       valgrind(1)

AUTHOR
       Maintained by the LLVM Team (https://llvm.org/).

COPYRIGHT
       2003-2020, LLVM Project

8                                 2020-03-19                            LIT(1)

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