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"
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 NAME.site.cfg when searching for test
suites, instead of lit.cfg and lit.site.cfg.
--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.
Suppress any output except for test failures.
Show less output, for example don't show information on tests that
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
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
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:
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
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 just Python modules which will be executed. When
the config file is executed, two important global variables are
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:
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
"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
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
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.
LIT EXAMPLE TESTS
The lit distribution contains several example implementations of test
suites in the ExampleTests directory.
Written by Daniel Dunbar and maintained by the LLVM Team