1 lit - LLVM Integrated Tester
2 ============================
7 :program:`lit` [*options*] [*tests*]
12 :program:`lit` is a portable tool for executing LLVM and Clang style test
13 suites, summarizing their results, and providing indication of failures.
14 :program:`lit` is designed to be a lightweight testing tool with as simple a
15 user interface as possible.
17 :program:`lit` should be run with one or more *tests* to run specified on the
18 command line. Tests can be either individual test files or directories to
19 search for tests (see :ref:`test-discovery`).
21 Each specified test will be executed (potentially in parallel) and once all
22 tests have been run :program:`lit` will print summary information on the number
23 of tests which passed or failed (see :ref:`test-status-results`). The
24 :program:`lit` program will execute with a non-zero exit code if any tests
27 By default :program:`lit` will use a succinct progress display and will only
28 print summary information for test failures. See :ref:`output-options` for
29 options controlling the :program:`lit` progress display and output.
31 :program:`lit` also includes a number of options for controlling how tests are
32 executed (specific features may depend on the particular test format). See
33 :ref:`execution-options` for more information.
35 Finally, :program:`lit` also supports additional options for only running a
36 subset of the options specified on the command line, see
37 :ref:`selection-options` for more information.
39 Users interested in the :program:`lit` architecture or designing a
40 :program:`lit` testing implementation should see :ref:`lit-infrastructure`.
45 .. option:: -h, --help
47 Show the :program:`lit` help message.
49 .. option:: -j N, --threads=N
51 Run ``N`` tests in parallel. By default, this is automatically chosen to
52 match the number of detected available CPUs.
54 .. option:: --config-prefix=NAME
56 Search for :file:`{NAME}.cfg` and :file:`{NAME}.site.cfg` when searching for
57 test suites, instead of :file:`lit.cfg` and :file:`lit.site.cfg`.
59 .. option:: -D NAME, -D NAME=VALUE, --param NAME, --param NAME=VALUE
61 Add a user defined parameter ``NAME`` with the given ``VALUE`` (or the empty
62 string if not given). The meaning and use of these parameters is test suite
70 .. option:: -q, --quiet
72 Suppress any output except for test failures.
74 .. option:: -s, --succinct
76 Show less output, for example don't show information on tests that pass.
78 .. option:: -v, --verbose
80 Show more information on test failures, for example the entire test output
81 instead of just the test result.
83 .. option:: -a, --show-all
85 Show more information about all tests, for example the entire test
86 commandline and output.
88 .. option:: --no-progress-bar
90 Do not use curses based progress bar.
92 .. option:: --show-unsupported
94 Show the names of unsupported tests.
96 .. option:: --show-xfail
98 Show the names of tests that were expected to fail.
100 .. _execution-options:
105 .. option:: --path=PATH
107 Specify an additional ``PATH`` to use when searching for executables in tests.
111 Run individual tests under valgrind (using the memcheck tool). The
112 ``--error-exitcode`` argument for valgrind is used so that valgrind failures
113 will cause the program to exit with a non-zero status.
115 When this option is enabled, :program:`lit` will also automatically provide a
116 "``valgrind``" feature that can be used to conditionally disable (or expect
117 failure in) certain tests.
119 .. option:: --vg-arg=ARG
121 When :option:`--vg` is used, specify an additional argument to pass to
122 :program:`valgrind` itself.
124 .. option:: --vg-leak
126 When :option:`--vg` is used, enable memory leak checks. When this option is
127 enabled, :program:`lit` will also automatically provide a "``vg_leak``"
128 feature that can be used to conditionally disable (or expect failure in)
131 .. option:: --time-tests
133 Track the wall time individual tests take to execute and includes the results
134 in the summary output. This is useful for determining which tests in a test
135 suite take the most time to execute. Note that this option is most useful
138 .. _selection-options:
143 .. option:: --max-tests=N
145 Run at most ``N`` tests and then terminate.
147 .. option:: --max-time=N
149 Spend at most ``N`` seconds (approximately) running tests and then terminate.
151 .. option:: --shuffle
153 Run the tests in a random order.
160 Run :program:`lit` in debug mode, for debugging configuration issues and
161 :program:`lit` itself.
163 .. option:: --show-suites
165 List the discovered test suites and exit.
167 .. option:: --show-tests
169 List all of the discovered tests and exit.
174 :program:`lit` will exit with an exit code of 1 if there are any FAIL or XPASS
175 results. Otherwise, it will exit with the status 0. Other exit codes are used
176 for non-test related failures (for example a user error or an internal program
184 The inputs passed to :program:`lit` can be either individual tests, or entire
185 directories or hierarchies of tests to run. When :program:`lit` starts up, the
186 first thing it does is convert the inputs into a complete list of tests to run
187 as part of *test discovery*.
189 In the :program:`lit` model, every test must exist inside some *test suite*.
190 :program:`lit` resolves the inputs specified on the command line to test suites
191 by searching upwards from the input path until it finds a :file:`lit.cfg` or
192 :file:`lit.site.cfg` file. These files serve as both a marker of test suites
193 and as configuration files which :program:`lit` loads in order to understand
194 how to find and run the tests inside the test suite.
196 Once :program:`lit` has mapped the inputs into test suites it traverses the
197 list of inputs adding tests for individual files and recursively searching for
198 tests in directories.
200 This behavior makes it easy to specify a subset of tests to run, while still
201 allowing the test suite configuration to control exactly how tests are
202 interpreted. In addition, :program:`lit` always identifies tests by the test
203 suite they are in, and their relative path inside the test suite. For
204 appropriately configured projects, this allows :program:`lit` to provide
205 convenient and flexible support for out-of-tree builds.
207 .. _test-status-results:
212 Each test ultimately produces one of the following six results:
220 The test failed, but that is expected. This is used for test formats which allow
221 specifying that a test does not currently work, but wish to leave it in the test
226 The test succeeded, but it was expected to fail. This is used for tests which
227 were specified as expected to fail, but are now succeeding (generally because
228 the feature they test was broken and has been fixed).
236 The test result could not be determined. For example, this occurs when the test
237 could not be run, the test itself is invalid, or the test was interrupted.
241 The test is not supported in this environment. This is used by test formats
242 which can report unsupported tests.
244 Depending on the test format tests may produce additional information about
245 their status (generally only for failures). See the :ref:`output-options`
246 section for more information.
248 .. _lit-infrastructure:
253 This section describes the :program:`lit` testing architecture for users interested in
254 creating a new :program:`lit` testing implementation, or extending an existing one.
256 :program:`lit` proper is primarily an infrastructure for discovering and running
257 arbitrary tests, and to expose a single convenient interface to these
258 tests. :program:`lit` itself doesn't know how to run tests, rather this logic is
259 defined by *test suites*.
264 As described in :ref:`test-discovery`, tests are always located inside a *test
265 suite*. Test suites serve to define the format of the tests they contain, the
266 logic for finding those tests, and any additional information to run the tests.
268 :program:`lit` identifies test suites as directories containing ``lit.cfg`` or
269 ``lit.site.cfg`` files (see also :option:`--config-prefix`). Test suites are
270 initially discovered by recursively searching up the directory hierarchy for
271 all the input files passed on the command line. You can use
272 :option:`--show-suites` to display the discovered test suites at startup.
274 Once a test suite is discovered, its config file is loaded. Config files
275 themselves are Python modules which will be executed. When the config file is
276 executed, two important global variables are predefined:
280 The global **lit** configuration object (a *LitConfig* instance), which defines
281 the builtin test formats, global configuration parameters, and other helper
282 routines for implementing test configurations.
286 This is the config object (a *TestingConfig* instance) for the test suite,
287 which the config file is expected to populate. The following variables are also
288 available on the *config* object, some of which must be set by the config and
289 others are optional or predefined:
291 **name** *[required]* The name of the test suite, for use in reports and
294 **test_format** *[required]* The test format object which will be used to
295 discover and run tests in the test suite. Generally this will be a builtin test
296 format available from the *lit.formats* module.
298 **test_source_root** The filesystem path to the test suite root. For out-of-dir
299 builds this is the directory that will be scanned for tests.
301 **test_exec_root** For out-of-dir builds, the path to the test suite root inside
302 the object directory. This is where tests will be run and temporary output files
305 **environment** A dictionary representing the environment to use when executing
308 **suffixes** For **lit** test formats which scan directories for tests, this
309 variable is a list of suffixes to identify test files. Used by: *ShTest*.
311 **substitutions** For **lit** test formats which substitute variables into a test
312 script, the list of substitutions to perform. Used by: *ShTest*.
314 **unsupported** Mark an unsupported directory, all tests within it will be
315 reported as unsupported. Used by: *ShTest*.
317 **parent** The parent configuration, this is the config object for the directory
318 containing the test suite, or None.
320 **root** The root configuration. This is the top-most :program:`lit` configuration in
323 **pipefail** Normally a test using a shell pipe fails if any of the commands
324 on the pipe fail. If this is not desired, setting this variable to false
325 makes the test fail only if the last command in the pipe fails.
330 Once test suites are located, :program:`lit` recursively traverses the source
331 directory (following *test_source_root*) looking for tests. When :program:`lit`
332 enters a sub-directory, it first checks to see if a nested test suite is
333 defined in that directory. If so, it loads that test suite recursively,
334 otherwise it instantiates a local test config for the directory (see
335 :ref:`local-configuration-files`).
337 Tests are identified by the test suite they are contained within, and the
338 relative path inside that suite. Note that the relative path may not refer to
339 an actual file on disk; some test formats (such as *GoogleTest*) define
340 "virtual tests" which have a path that contains both the path to the actual
341 test file and a subpath to identify the virtual test.
343 .. _local-configuration-files:
345 LOCAL CONFIGURATION FILES
346 ~~~~~~~~~~~~~~~~~~~~~~~~~
348 When :program:`lit` loads a subdirectory in a test suite, it instantiates a
349 local test configuration by cloning the configuration for the parent directory
350 --- the root of this configuration chain will always be a test suite. Once the
351 test configuration is cloned :program:`lit` checks for a *lit.local.cfg* file
352 in the subdirectory. If present, this file will be loaded and can be used to
353 specialize the configuration for each individual directory. This facility can
354 be used to define subdirectories of optional tests, or to change other
355 configuration parameters --- for example, to change the test format, or the
356 suffixes which identify test files.
358 TEST RUN OUTPUT FORMAT
359 ~~~~~~~~~~~~~~~~~~~~~~
361 The :program:`lit` output for a test run conforms to the following schema, in
362 both short and verbose modes (although in short mode no PASS lines will be
363 shown). This schema has been chosen to be relatively easy to reliably parse by
364 a machine (for example in buildbot log scraping), and for other tools to
367 Each test result is expected to appear on a line that matches:
371 <result code>: <test name> (<progress info>)
373 where ``<result-code>`` is a standard test result such as PASS, FAIL, XFAIL,
374 XPASS, UNRESOLVED, or UNSUPPORTED. The performance result codes of IMPROVED and
375 REGRESSED are also allowed.
377 The ``<test name>`` field can consist of an arbitrary string containing no
380 The ``<progress info>`` field can be used to report progress information such
381 as (1/300) or can be empty, but even when empty the parentheses are required.
383 Each test result may include additional (multiline) log information in the
388 <log delineator> TEST '(<test name>)' <trailing delineator>
392 where ``<test name>`` should be the name of a preceding reported test, ``<log
393 delineator>`` is a string of "*" characters *at least* four characters long
394 (the recommended length is 20), and ``<trailing delineator>`` is an arbitrary
397 The following is an example of a test run output which consists of four tests A,
398 B, C, and D, and a log message for the failing test C:
405 ******************** TEST 'C' FAILED ********************
406 Test 'C' failed as a result of exit code 1.
413 The :program:`lit` distribution contains several example implementations of
414 test suites in the *ExampleTests* directory.