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:: --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:: --no-progress-bar
85 Do not use curses based progress bar.
87 .. _execution-options:
92 .. option:: --path=PATH
94 Specify an additional ``PATH`` to use when searching for executables in tests.
98 Run individual tests under valgrind (using the memcheck tool). The
99 ``--error-exitcode`` argument for valgrind is used so that valgrind failures
100 will cause the program to exit with a non-zero status.
102 When this option is enabled, :program:`lit` will also automatically provide a
103 "``valgrind``" feature that can be used to conditionally disable (or expect
104 failure in) certain tests.
106 .. option:: --vg-arg=ARG
108 When :option:`--vg` is used, specify an additional argument to pass to
109 :program:`valgrind` itself.
111 .. option:: --vg-leak
113 When :option:`--vg` is used, enable memory leak checks. When this option is
114 enabled, :program:`lit` will also automatically provide a "``vg_leak``"
115 feature that can be used to conditionally disable (or expect failure in)
118 .. option:: --time-tests
120 Track the wall time individual tests take to execute and includes the results
121 in the summary output. This is useful for determining which tests in a test
122 suite take the most time to execute. Note that this option is most useful
125 .. _selection-options:
130 .. option:: --max-tests=N
132 Run at most ``N`` tests and then terminate.
134 .. option:: --max-time=N
136 Spend at most ``N`` seconds (approximately) running tests and then terminate.
138 .. option:: --shuffle
140 Run the tests in a random order.
147 Run :program:`lit` in debug mode, for debugging configuration issues and
148 :program:`lit` itself.
150 .. option:: --show-suites
152 List the discovered test suites and exit.
154 .. option:: --show-tests
156 List all of the the discovered tests and exit.
161 :program:`lit` will exit with an exit code of 1 if there are any FAIL or XPASS
162 results. Otherwise, it will exit with the status 0. Other exit codes are used
163 for non-test related failures (for example a user error or an internal program
171 The inputs passed to :program:`lit` can be either individual tests, or entire
172 directories or hierarchies of tests to run. When :program:`lit` starts up, the
173 first thing it does is convert the inputs into a complete list of tests to run
174 as part of *test discovery*.
176 In the :program:`lit` model, every test must exist inside some *test suite*.
177 :program:`lit` resolves the inputs specified on the command line to test suites
178 by searching upwards from the input path until it finds a :file:`lit.cfg` or
179 :file:`lit.site.cfg` file. These files serve as both a marker of test suites
180 and as configuration files which :program:`lit` loads in order to understand
181 how to find and run the tests inside the test suite.
183 Once :program:`lit` has mapped the inputs into test suites it traverses the
184 list of inputs adding tests for individual files and recursively searching for
185 tests in directories.
187 This behavior makes it easy to specify a subset of tests to run, while still
188 allowing the test suite configuration to control exactly how tests are
189 interpreted. In addition, :program:`lit` always identifies tests by the test
190 suite they are in, and their relative path inside the test suite. For
191 appropriately configured projects, this allows :program:`lit` to provide
192 convenient and flexible support for out-of-tree builds.
194 .. _test-status-results:
199 Each test ultimately produces one of the following six results:
207 The test failed, but that is expected. This is used for test formats which allow
208 specifying that a test does not currently work, but wish to leave it in the test
213 The test succeeded, but it was expected to fail. This is used for tests which
214 were specified as expected to fail, but are now succeeding (generally because
215 the feature they test was broken and has been fixed).
223 The test result could not be determined. For example, this occurs when the test
224 could not be run, the test itself is invalid, or the test was interrupted.
228 The test is not supported in this environment. This is used by test formats
229 which can report unsupported tests.
231 Depending on the test format tests may produce additional information about
232 their status (generally only for failures). See the :ref:`output-options`
233 section for more information.
235 .. _lit-infrastructure:
240 This section describes the :program:`lit` testing architecture for users interested in
241 creating a new :program:`lit` testing implementation, or extending an existing one.
243 :program:`lit` proper is primarily an infrastructure for discovering and running
244 arbitrary tests, and to expose a single convenient interface to these
245 tests. :program:`lit` itself doesn't know how to run tests, rather this logic is
246 defined by *test suites*.
251 As described in :ref:`test-discovery`, tests are always located inside a *test
252 suite*. Test suites serve to define the format of the tests they contain, the
253 logic for finding those tests, and any additional information to run the tests.
255 :program:`lit` identifies test suites as directories containing ``lit.cfg`` or
256 ``lit.site.cfg`` files (see also :option:`--config-prefix`). Test suites are
257 initially discovered by recursively searching up the directory hierarchy for
258 all the input files passed on the command line. You can use
259 :option:`--show-suites` to display the discovered test suites at startup.
261 Once a test suite is discovered, its config file is loaded. Config files
262 themselves are Python modules which will be executed. When the config file is
263 executed, two important global variables are predefined:
267 The global **lit** configuration object (a *LitConfig* instance), which defines
268 the builtin test formats, global configuration parameters, and other helper
269 routines for implementing test configurations.
273 This is the config object (a *TestingConfig* instance) for the test suite,
274 which the config file is expected to populate. The following variables are also
275 available on the *config* object, some of which must be set by the config and
276 others are optional or predefined:
278 **name** *[required]* The name of the test suite, for use in reports and
281 **test_format** *[required]* The test format object which will be used to
282 discover and run tests in the test suite. Generally this will be a builtin test
283 format available from the *lit.formats* module.
285 **test_source_root** The filesystem path to the test suite root. For out-of-dir
286 builds this is the directory that will be scanned for tests.
288 **test_exec_root** For out-of-dir builds, the path to the test suite root inside
289 the object directory. This is where tests will be run and temporary output files
292 **environment** A dictionary representing the environment to use when executing
295 **suffixes** For **lit** test formats which scan directories for tests, this
296 variable is a list of suffixes to identify test files. Used by: *ShTest*.
298 **substitutions** For **lit** test formats which substitute variables into a test
299 script, the list of substitutions to perform. Used by: *ShTest*.
301 **unsupported** Mark an unsupported directory, all tests within it will be
302 reported as unsupported. Used by: *ShTest*.
304 **parent** The parent configuration, this is the config object for the directory
305 containing the test suite, or None.
307 **root** The root configuration. This is the top-most :program:`lit` configuration in
310 **on_clone** The config is actually cloned for every subdirectory inside a test
311 suite, to allow local configuration on a per-directory basis. The *on_clone*
312 variable can be set to a Python function which will be called whenever a
313 configuration is cloned (for a subdirectory). The function should takes three
314 arguments: (1) the parent configuration, (2) the new configuration (which the
315 *on_clone* function will generally modify), and (3) the test path to the new
316 directory being scanned.
318 **pipefail** Normally a test using a shell pipe fails if any of the commands
319 on the pipe fail. If this is not desired, setting this variable to false
320 makes the test fail only if the last command in the pipe fails.
325 Once test suites are located, :program:`lit` recursively traverses the source
326 directory (following *test_source_root*) looking for tests. When :program:`lit`
327 enters a sub-directory, it first checks to see if a nested test suite is
328 defined in that directory. If so, it loads that test suite recursively,
329 otherwise it instantiates a local test config for the directory (see
330 :ref:`local-configuration-files`).
332 Tests are identified by the test suite they are contained within, and the
333 relative path inside that suite. Note that the relative path may not refer to
334 an actual file on disk; some test formats (such as *GoogleTest*) define
335 "virtual tests" which have a path that contains both the path to the actual
336 test file and a subpath to identify the virtual test.
338 .. _local-configuration-files:
340 LOCAL CONFIGURATION FILES
341 ~~~~~~~~~~~~~~~~~~~~~~~~~
343 When :program:`lit` loads a subdirectory in a test suite, it instantiates a
344 local test configuration by cloning the configuration for the parent direction
345 --- the root of this configuration chain will always be a test suite. Once the
346 test configuration is cloned :program:`lit` checks for a *lit.local.cfg* file
347 in the subdirectory. If present, this file will be loaded and can be used to
348 specialize the configuration for each individual directory. This facility can
349 be used to define subdirectories of optional tests, or to change other
350 configuration parameters --- for example, to change the test format, or the
351 suffixes which identify test files.
353 TEST RUN OUTPUT FORMAT
354 ~~~~~~~~~~~~~~~~~~~~~~
356 The :program:`lit` output for a test run conforms to the following schema, in
357 both short and verbose modes (although in short mode no PASS lines will be
358 shown). This schema has been chosen to be relatively easy to reliably parse by
359 a machine (for example in buildbot log scraping), and for other tools to
362 Each test result is expected to appear on a line that matches:
366 <result code>: <test name> (<progress info>)
368 where ``<result-code>`` is a standard test result such as PASS, FAIL, XFAIL,
369 XPASS, UNRESOLVED, or UNSUPPORTED. The performance result codes of IMPROVED and
370 REGRESSED are also allowed.
372 The ``<test name>`` field can consist of an arbitrary string containing no
375 The ``<progress info>`` field can be used to report progress information such
376 as (1/300) or can be empty, but even when empty the parentheses are required.
378 Each test result may include additional (multiline) log information in the
383 <log delineator> TEST '(<test name>)' <trailing delineator>
387 where ``<test name>`` should be the name of a preceding reported test, ``<log
388 delineator>`` is a string of "*" characters *at least* four characters long
389 (the recommended length is 20), and ``<trailing delineator>`` is an arbitrary
392 The following is an example of a test run output which consists of four tests A,
393 B, C, and D, and a log message for the failing test C:
400 ******************** TEST 'C' FAILED ********************
401 Test 'C' failed as a result of exit code 1.
408 The :program:`lit` distribution contains several example implementations of
409 test suites in the *ExampleTests* directory.