LIT(1)                               LLVM                               LIT(1)

       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  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
       executed (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 INFRASTRUCTURE.

       -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.

              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 param-
              eters 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 pass.

       -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 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

              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.

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

              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.

              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 itself.

              List the discovered test suites and exit.

              List all of the the discovered tests and exit.

       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).

       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  con-
       venient 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 for-
          mats 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 succeed-
          ing (generally because the feature they test was broken and has been

          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
       OPTIONS section for more information.

       This  section  describes  the lit testing architecture for users inter-
       ested 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 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 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:

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

          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:

          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.

          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 gener-
          ally modify), and (3) the test  path  to  the  new  directory  being

          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.

       Once test suites are located,  lit  recursively  traverses  the  source
       directory  (following  test_source_root)  looking  for tests.  When 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 recur-
       sively, otherwise it instantiates a local test config for the directory

       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 direc-
       tion --- 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 indi-
       vidual 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

       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

       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)

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


       Maintained by The LLVM Team (

       2003-2016, LLVM Project

3.5                               2016-10-07                            LIT(1)

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