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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, sum-
marizing their results, and providing indication of failures. lit is de-
signed 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 concurrently) 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 con-
trolling the lit progress display and output.

lit also includes a number of options for controlling how tests are exe-
cuted (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.

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

Users interested in the lit architecture or designing a lit testing imple-
mentation should see LIT INFRASTRUCTURE.

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

-j N, --workers=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. Also show a progress bar, unless --no-progress-bar is speci-
fied.

-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 com-
mand (: in the case of bash) with argument 'RUN: at line N' before
each command pipeline, and this option also causes those no-op com-
mands 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 ex-
pect failure in) certain tests.

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

--ignore-fail
Exit with status zero even if some tests fail.

--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
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 --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.

--shuffle
Run the tests in a random order, not failing/slowest first. Depre-
cated, use --order instead.

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

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

--max-time=N
Spend at most N seconds (approximately) running tests and then ter-
minate. Note that this is not an alias for --timeout; the two are
different kinds of maximums.

--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 environ-
ment variable LIT_NUM_SHARDS can also be used in place of this op-
tion. These two options provide a coarse mechanism for partitioning
large testsuites, for parallel execution on separate machines (say
in a large testing farm).

--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.

--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.

--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 --max-time; the two are different kinds of maxi-
mums.

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

--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 en-
vironments where the call to lit is issued indirectly.

--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:

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

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

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 ex-
ample not to treat the nvptx64-nvidia-cuda version of offload-
ing/memory_manager.cpp as XFAIL:

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

--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 --xfail and LIT_XFAIL. --xfail-not and
LIT_XFAIL_NOT always override all other XFAIL specifications, in-
cluding an --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
--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 directo-
ries 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 re-
solves 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 ap-
propriately 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 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 (gener-
ally 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 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 arbi-
trary 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 dis-
play 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 de-
fines 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 diag-
nostics.

test_format [required] The test format object which will be used to dis-
cover 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 tempo-
rary output files placed.

environment A dictionary representing the environment to use when exe-
cuting 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 di-
rectory 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, RE-
QUIRES, and UNSUPPORTED directives.

TEST DISCOVERY
Once test suites are located, lit recursively traverses the source direc-
tory (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 spe-
cialize the configuration for each individual directory. This facility can
be used to define subdirectories of optional tests, or to change other con-
figuration parameters --- for example, to change the test format, or the
suffixes which identify test files.

SUBSTITUTIONS
lit allows patterns to be substituted inside RUN commands. It also provides
the following base set of substitutions, which are defined in TestRun-
ner.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 |
+-------------------------+-----------------------------+
| %t | temporary file name unique |
| | to the test |
+-------------------------+-----------------------------+
| %basename_t | The last path component of |
| | %t but without the .tmp ex- |
| | tension |
+-------------------------+-----------------------------+
| %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 LOCAL CONFIGURATION FILES.

By default, substitutions are expanded exactly once, so that if e.g. a sub-
stitution %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 sub-
stitutions again would yield a different result.

More detailed information on substitutions can be found in the LLVM Testing
Infrastructure Guide.

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 IM-
PROVED and REGRESSED are also allowed.

The <test name> field can consist of an arbitrary string containing no new-
line.

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 re-
quired.

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 de-
lineator> is a string of "*" characters at least four characters long (the
recommended length is 20), and <trailing delineator> is an arbitrary (un-
parsed) 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.