t/README: Document the do's and don'ts of tests
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1Core GIT Tests
2==============
3
4This directory holds many test scripts for core GIT tools. The
5first part of this short document describes how to run the tests
6and read their output.
7
8When fixing the tools or adding enhancements, you are strongly
9encouraged to add tests in this directory to cover what you are
10trying to fix or enhance. The later part of this short document
11describes how your test scripts should be organized.
12
13
14Running Tests
15-------------
16
17The easiest way to run tests is to say "make". This runs all
18the tests.
19
20 *** t0000-basic.sh ***
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21 ok 1 - .git/objects should be empty after git init in an empty repo.
22 ok 2 - .git/objects should have 3 subdirectories.
23 ok 3 - success is reported like this
986aa7f1 24 ...
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25 ok 43 - very long name in the index handled sanely
26 # fixed 1 known breakage(s)
27 # still have 1 known breakage(s)
28 # passed all remaining 42 test(s)
29 1..43
30 *** t0001-init.sh ***
31 ok 1 - plain
32 ok 2 - plain with GIT_WORK_TREE
33 ok 3 - plain bare
34
35Since the tests all output TAP (see http://testanything.org) they can
85b0b34e 36be run with any TAP harness. Here's an example of parallel testing
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37powered by a recent version of prove(1):
38
39 $ prove --timer --jobs 15 ./t[0-9]*.sh
40 [19:17:33] ./t0005-signals.sh ................................... ok 36 ms
41 [19:17:33] ./t0022-crlf-rename.sh ............................... ok 69 ms
42 [19:17:33] ./t0024-crlf-archive.sh .............................. ok 154 ms
43 [19:17:33] ./t0004-unwritable.sh ................................ ok 289 ms
44 [19:17:33] ./t0002-gitfile.sh ................................... ok 480 ms
45 ===( 102;0 25/? 6/? 5/? 16/? 1/? 4/? 2/? 1/? 3/? 1... )===
46
47prove and other harnesses come with a lot of useful options. The
48--state option in particular is very useful:
49
50 # Repeat until no more failures
51 $ prove -j 15 --state=failed,save ./t[0-9]*.sh
986aa7f1 52
5099b99d 53You can also run each test individually from command line, like this:
986aa7f1 54
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55 $ sh ./t3010-ls-files-killed-modified.sh
56 ok 1 - git update-index --add to add various paths.
57 ok 2 - git ls-files -k to show killed files.
58 ok 3 - validate git ls-files -k output.
59 ok 4 - git ls-files -m to show modified files.
60 ok 5 - validate git ls-files -m output.
61 # passed all 5 test(s)
62 1..5
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63
64You can pass --verbose (or -v), --debug (or -d), and --immediate
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65(or -i) command line argument to the test, or by setting GIT_TEST_OPTS
66appropriately before running "make".
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67
68--verbose::
69 This makes the test more verbose. Specifically, the
70 command being run and their output if any are also
71 output.
72
73--debug::
74 This may help the person who is developing a new test.
75 It causes the command defined with test_debug to run.
76
77--immediate::
78 This causes the test to immediately exit upon the first
79 failed test.
80
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81--long-tests::
82 This causes additional long-running tests to be run (where
83 available), for more exhaustive testing.
84
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85--valgrind::
86 Execute all Git binaries with valgrind and exit with status
87 126 on errors (just like regular tests, this will only stop
88 the test script when running under -i). Valgrind errors
89 go to stderr, so you might want to pass the -v option, too.
986aa7f1 90
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91 Since it makes no sense to run the tests with --valgrind and
92 not see any output, this option implies --verbose. For
93 convenience, it also implies --tee.
94
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95--tee::
96 In addition to printing the test output to the terminal,
97 write it to files named 't/test-results/$TEST_NAME.out'.
98 As the names depend on the tests' file names, it is safe to
99 run the tests with this option in parallel.
100
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101--with-dashes::
102 By default tests are run without dashed forms of
103 commands (like git-commit) in the PATH (it only uses
104 wrappers from ../bin-wrappers). Use this option to include
105 the build directory (..) in the PATH, which contains all
106 the dashed forms of commands. This option is currently
107 implied by other options like --valgrind and
108 GIT_TEST_INSTALLED.
109
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110--root=<directory>::
111 Create "trash" directories used to store all temporary data during
112 testing under <directory>, instead of the t/ directory.
113 Using this option with a RAM-based filesystem (such as tmpfs)
114 can massively speed up the test suite.
115
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116You can also set the GIT_TEST_INSTALLED environment variable to
117the bindir of an existing git installation to test that installation.
118You still need to have built this git sandbox, from which various
119test-* support programs, templates, and perl libraries are used.
120If your installed git is incomplete, it will silently test parts of
121your built version instead.
122
123When using GIT_TEST_INSTALLED, you can also set GIT_TEST_EXEC_PATH to
124override the location of the dashed-form subcommands (what
125GIT_EXEC_PATH would be used for during normal operation).
126GIT_TEST_EXEC_PATH defaults to `$GIT_TEST_INSTALLED/git --exec-path`.
127
128
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129Skipping Tests
130--------------
131
132In some environments, certain tests have no way of succeeding
133due to platform limitation, such as lack of 'unzip' program, or
134filesystem that do not allow arbitrary sequence of non-NUL bytes
135as pathnames.
136
137You should be able to say something like
138
139 $ GIT_SKIP_TESTS=t9200.8 sh ./t9200-git-cvsexport-commit.sh
140
141and even:
142
143 $ GIT_SKIP_TESTS='t[0-4]??? t91?? t9200.8' make
144
145to omit such tests. The value of the environment variable is a
146SP separated list of patterns that tells which tests to skip,
147and either can match the "t[0-9]{4}" part to skip the whole
148test, or t[0-9]{4} followed by ".$number" to say which
149particular test to skip.
150
151Note that some tests in the existing test suite rely on previous
152test item, so you cannot arbitrarily disable one and expect the
153remainder of test to check what the test originally was intended
154to check.
155
156
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157Naming Tests
158------------
159
160The test files are named as:
161
162 tNNNN-commandname-details.sh
163
164where N is a decimal digit.
165
166First digit tells the family:
167
168 0 - the absolute basics and global stuff
169 1 - the basic commands concerning database
170 2 - the basic commands concerning the working tree
171 3 - the other basic commands (e.g. ls-files)
172 4 - the diff commands
173 5 - the pull and exporting commands
174 6 - the revision tree commands (even e.g. merge-base)
8f4a9b62 175 7 - the porcelainish commands concerning the working tree
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176 8 - the porcelainish commands concerning forensics
177 9 - the git tools
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178
179Second digit tells the particular command we are testing.
180
181Third digit (optionally) tells the particular switch or group of switches
182we are testing.
183
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184If you create files under t/ directory (i.e. here) that is not
185the top-level test script, never name the file to match the above
186pattern. The Makefile here considers all such files as the
187top-level test script and tries to run all of them. A care is
188especially needed if you are creating a common test library
189file, similar to test-lib.sh, because such a library file may
190not be suitable for standalone execution.
191
f50c9f76 192
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193Writing Tests
194-------------
195
196The test script is written as a shell script. It should start
197with the standard "#!/bin/sh" with copyright notices, and an
198assignment to variable 'test_description', like this:
199
200 #!/bin/sh
201 #
202 # Copyright (c) 2005 Junio C Hamano
203 #
204
14cd1ff3 205 test_description='xxx test (option --frotz)
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206
207 This test registers the following structure in the cache
208 and tries to run git-ls-files with option --frotz.'
209
f50c9f76 210
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211Source 'test-lib.sh'
212--------------------
213
214After assigning test_description, the test script should source
215test-lib.sh like this:
216
217 . ./test-lib.sh
218
219This test harness library does the following things:
220
221 - If the script is invoked with command line argument --help
222 (or -h), it shows the test_description and exits.
223
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224 - Creates an empty test directory with an empty .git/objects database
225 and chdir(2) into it. This directory is 't/trash
226 directory.$test_name_without_dotsh', with t/ subject to change by
227 the --root option documented above.
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228
229 - Defines standard test helper functions for your scripts to
230 use. These functions are designed to make all scripts behave
231 consistently when command line arguments --verbose (or -v),
232 --debug (or -d), and --immediate (or -i) is given.
233
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234Do's, don'ts & things to keep in mind
235-------------------------------------
236
237Here's a few examples of things you probably should and shouldn't do
238when writing tests.
239
240Do:
241
242 - Put as much code as possible inside test_expect_success and other
243 assertions.
244
245 Even code that isn't a test per se, but merely some setup code
246 should be inside a test assertion if at all possible. Test scripts
247 should only have trivial code outside of their assertions.
248
249 - Chain your test assertions
250
251 Write test code like this:
252
253 git merge foo &&
254 git push bar &&
255 test ...
256
257 Instead of:
258
259 git merge hla
260 git push gh
261 test ...
262
263 That way all of the commands in your tests will succeed or fail. If
264 you must ignore the return value of something (e.g. the return
265 value of export is unportable) it's best to indicate so explicitly
266 with a semicolon:
267
268 export HLAGH;
269 git merge hla &&
270 git push gh &&
271 test ...
272
273Don't:
274
275 - exit() within a <script> part.
276
277 The harness will catch this as a programming error of the test.
278 Use test_done instead if you need to stop the tests early (see
279 "Skipping tests" below).
280
281 - Break the TAP output
282
283 The raw output from your test might be interpreted by a TAP
284 harness. You usually don't have to worry about that. TAP harnesses
285 will ignore everything they don't know about, but don't step on
286 their toes in these areas:
287
288 - Don't print lines like "$x..$y" where $x and $y are integers.
289
290 - Don't print lines that begin with "ok" or "not ok".
291
292 A TAP harness expect a line that begins with either "ok" and "not
293 ok" to signal a test passed or failed (and our harness already
294 produces such lines), so your script shouldn't emit such lines to
295 their output.
296
297 You can glean some further possible issues from the TAP grammar
298 (see http://search.cpan.org/perldoc?TAP::Parser::Grammar#TAP_Grammar)
299 but the best indication is to just run the tests with prove(1),
300 it'll complain if anything is amiss.
301
302Keep in mind:
303
304 - That what you print to stderr and stdout is usually ignored
305
306 Inside <script> part, the standard output and standard error
307 streams are discarded, and the test harness only reports "ok" or
308 "not ok" to the end user running the tests. Under --verbose, they
309 are shown to help debugging the tests.
310
311
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312Skipping tests
313--------------
314
315If you need to skip all the remaining tests you should set skip_all
316and immediately call test_done. The string you give to skip_all will
317be used as an explanation for why the test was skipped. for instance:
318
319 if ! test_have_prereq PERL
320 then
321 skip_all='skipping perl interface tests, perl not available'
322 test_done
323 fi
14cd1ff3 324
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325End with test_done
326------------------
327
328Your script will be a sequence of tests, using helper functions
329from the test harness library. At the end of the script, call
330'test_done'.
331
332
333Test harness library
334--------------------
335
336There are a handful helper functions defined in the test harness
337library for your script to use.
338
9a897893 339 - test_expect_success [<prereq>] <message> <script>
986aa7f1 340
9a897893 341 Usually takes two strings as parameter, and evaluates the
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342 <script>. If it yields success, test is considered
343 successful. <message> should state what it is testing.
344
345 Example:
346
347 test_expect_success \
348 'git-write-tree should be able to write an empty tree.' \
349 'tree=$(git-write-tree)'
350
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351 If you supply three parameters the first will be taken to be a
352 prerequisite, see the test_set_prereq and test_have_prereq
353 documentation below:
354
355 test_expect_success TTY 'git --paginate rev-list uses a pager' \
356 ' ... '
357
358 - test_expect_failure [<prereq>] <message> <script>
986aa7f1 359
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360 This is NOT the opposite of test_expect_success, but is used
361 to mark a test that demonstrates a known breakage. Unlike
362 the usual test_expect_success tests, which say "ok" on
363 success and "FAIL" on failure, this will say "FIXED" on
364 success and "still broken" on failure. Failures from these
365 tests won't cause -i (immediate) to stop.
986aa7f1 366
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367 Like test_expect_success this function can optionally use a three
368 argument invocation with a prerequisite as the first argument.
369
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370 - test_expect_code [<prereq>] <code> <message> <script>
371
372 Analogous to test_expect_success, but pass the test if it exits
373 with a given exit <code>
374
375 test_expect_code 1 'Merge with d/f conflicts' 'git merge "merge msg" B master'
376
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377 - test_debug <script>
378
379 This takes a single argument, <script>, and evaluates it only
380 when the test script is started with --debug command line
381 argument. This is primarily meant for use during the
382 development of a new test script.
383
384 - test_done
385
386 Your test script must have test_done at the end. Its purpose
387 is to summarize successes and failures in the test script and
388 exit with an appropriate error code.
389
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390 - test_tick
391
392 Make commit and tag names consistent by setting the author and
393 committer times to defined stated. Subsequent calls will
394 advance the times by a fixed amount.
395
396 - test_commit <message> [<filename> [<contents>]]
397
398 Creates a commit with the given message, committing the given
399 file with the given contents (default for both is to reuse the
400 message string), and adds a tag (again reusing the message
401 string as name). Calls test_tick to make the SHA-1s
402 reproducible.
403
404 - test_merge <message> <commit-or-tag>
405
406 Merges the given rev using the given message. Like test_commit,
407 creates a tag and calls test_tick before committing.
986aa7f1 408
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409 - test_set_prereq SOME_PREREQ
410
411 Set a test prerequisite to be used later with test_have_prereq. The
412 test-lib will set some prerequisites for you, e.g. PERL and PYTHON
413 which are derived from ./GIT-BUILD-OPTIONS (grep test_set_prereq
414 test-lib.sh for more). Others you can set yourself and use later
415 with either test_have_prereq directly, or the three argument
416 invocation of test_expect_success and test_expect_failure.
417
418 - test_have_prereq SOME PREREQ
419
420 Check if we have a prerequisite previously set with
421 test_set_prereq. The most common use of this directly is to skip
422 all the tests if we don't have some essential prerequisite:
423
424 if ! test_have_prereq PERL
425 then
426 skip_all='skipping perl interface tests, perl not available'
427 test_done
428 fi
429
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430 - test_external [<prereq>] <message> <external> <script>
431
432 Execute a <script> with an <external> interpreter (like perl). This
433 was added for tests like t9700-perl-git.sh which do most of their
434 work in an external test script.
435
436 test_external \
437 'GitwebCache::*FileCache*' \
438 "$PERL_PATH" "$TEST_DIRECTORY"/t9503/test_cache_interface.pl
439
440 If the test is outputting its own TAP you should set the
441 test_external_has_tap variable somewhere before calling the first
442 test_external* function. See t9700-perl-git.sh for an example.
443
444 # The external test will outputs its own plan
445 test_external_has_tap=1
446
447 - test_external_without_stderr [<prereq>] <message> <external> <script>
448
449 Like test_external but fail if there's any output on stderr,
450 instead of checking the exit code.
451
452 test_external_without_stderr \
453 'Perl API' \
454 "$PERL_PATH" "$TEST_DIRECTORY"/t9700/test.pl
455
456
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457Tips for Writing Tests
458----------------------
459
460As with any programming projects, existing programs are the best
461source of the information. However, do _not_ emulate
462t0000-basic.sh when writing your tests. The test is special in
463that it tries to validate the very core of GIT. For example, it
464knows that there will be 256 subdirectories under .git/objects/,
465and it knows that the object ID of an empty tree is a certain
46640-byte string. This is deliberately done so in t0000-basic.sh
467because the things the very basic core test tries to achieve is
468to serve as a basis for people who are changing the GIT internal
469drastically. For these people, after making certain changes,
470not seeing failures from the basic test _is_ a failure. And
471such drastic changes to the core GIT that even changes these
472otherwise supposedly stable object IDs should be accompanied by
473an update to t0000-basic.sh.
474
475However, other tests that simply rely on basic parts of the core
476GIT working properly should not have that level of intimate
477knowledge of the core GIT internals. If all the test scripts
478hardcoded the object IDs like t0000-basic.sh does, that defeats
479the purpose of t0000-basic.sh, which is to isolate that level of
480validation in one place. Your test also ends up needing
481updating when such a change to the internal happens, so do _not_
482do it and leave the low level of validation to t0000-basic.sh.