Ubuntu Manpage: lit - LLVM Integrated Tester

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
       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 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.

GENERAL OPTIONS

       -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.

       --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 parameters 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 implies --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 valgrind 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”  feature that can be used to conditionally disable (or expect
              failure in) certain tests.

       --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.
              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 environment
              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 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

       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
       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 convenient 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 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.

       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.

LIT INFRASTRUCTURE

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.

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 lit.site.cfg 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_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 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, 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 recursively, 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 directory — 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.

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 ../TestingGuide.

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
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:

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.

AUTHOR

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

COPYRIGHT

       2003-2020, LLVM Project