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.
- --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.
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.
- --no-progress-bar
- Do not use curses based progress bar.
EXECUTION OPTIONS¶
- --path=PATH
- Specify an addition 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.
- --vg-arg=ARG
- When --vg is used, specify an additional argument to
pass to valgrind itself.
- --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.
ADDITIONAL OPTIONS¶
- --debug
- Run lit in debug mode, for debugging configuration
issues and lit itself.
- --show-suites
- List the discovered test suites as part of the standard
output.
- --no-tcl-as-sh
- Run Tcl scripts internally (instead of converting to shell
scripts).
- --repeat=N
- Run each test N times. Currently this is primarily
useful for timing tests, other results are not collated in any reasonable
fashion.
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 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
- 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_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 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, TclTest.
substitutions For lit test formats which substitute variables
into a test script, the list of substitutions to perform. Used by:
ShTest, TclTest.
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.
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 generally
modify), and (3) the test path to the new directory being scanned.
TEST DISCOVERY¶
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 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 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.
The b<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 preceeding 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.
Example Test Run Output Listing
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¶
Written by Daniel Dunbar and maintained by the LLVM Team
(<
http://llvm.org/>).
POD ERRORS¶
Hey!
The above document had some coding errors, which are explained
below:
- Around line 389:
- =back without =over