t/README: Document the predefined test prerequisites
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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
6fd45295 237Here are a few examples of things you probably should and shouldn't do
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238when writing tests.
239
240Do:
241
6fd45295 242 - Put all code inside test_expect_success and other assertions.
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243
244 Even code that isn't a test per se, but merely some setup code
6fd45295 245 should be inside a test assertion.
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246
247 - Chain your test assertions
248
249 Write test code like this:
250
251 git merge foo &&
252 git push bar &&
253 test ...
254
255 Instead of:
256
257 git merge hla
258 git push gh
259 test ...
260
261 That way all of the commands in your tests will succeed or fail. If
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262 you must ignore the return value of something (e.g., the return
263 after unsetting a variable that was already unset is unportable) it's
264 best to indicate so explicitly with a semicolon:
20873f45 265
bdcaa325 266 unset HLAGH;
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267 git merge hla &&
268 git push gh &&
269 test ...
270
271Don't:
272
273 - exit() within a <script> part.
274
275 The harness will catch this as a programming error of the test.
276 Use test_done instead if you need to stop the tests early (see
277 "Skipping tests" below).
278
279 - Break the TAP output
280
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281 The raw output from your test may be interpreted by a TAP harness. TAP
282 harnesses will ignore everything they don't know about, but don't step
283 on their toes in these areas:
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284
285 - Don't print lines like "$x..$y" where $x and $y are integers.
286
287 - Don't print lines that begin with "ok" or "not ok".
288
6fd45295 289 TAP harnesses expect a line that begins with either "ok" and "not
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290 ok" to signal a test passed or failed (and our harness already
291 produces such lines), so your script shouldn't emit such lines to
292 their output.
293
294 You can glean some further possible issues from the TAP grammar
295 (see http://search.cpan.org/perldoc?TAP::Parser::Grammar#TAP_Grammar)
296 but the best indication is to just run the tests with prove(1),
297 it'll complain if anything is amiss.
298
299Keep in mind:
300
6fd45295 301 - Inside <script> part, the standard output and standard error
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302 streams are discarded, and the test harness only reports "ok" or
303 "not ok" to the end user running the tests. Under --verbose, they
304 are shown to help debugging the tests.
305
306
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307Skipping tests
308--------------
309
310If you need to skip all the remaining tests you should set skip_all
311and immediately call test_done. The string you give to skip_all will
312be used as an explanation for why the test was skipped. for instance:
313
314 if ! test_have_prereq PERL
315 then
316 skip_all='skipping perl interface tests, perl not available'
317 test_done
318 fi
14cd1ff3 319
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320End with test_done
321------------------
322
323Your script will be a sequence of tests, using helper functions
324from the test harness library. At the end of the script, call
325'test_done'.
326
327
328Test harness library
329--------------------
330
331There are a handful helper functions defined in the test harness
332library for your script to use.
333
9a897893 334 - test_expect_success [<prereq>] <message> <script>
986aa7f1 335
9a897893 336 Usually takes two strings as parameter, and evaluates the
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337 <script>. If it yields success, test is considered
338 successful. <message> should state what it is testing.
339
340 Example:
341
342 test_expect_success \
343 'git-write-tree should be able to write an empty tree.' \
344 'tree=$(git-write-tree)'
345
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346 If you supply three parameters the first will be taken to be a
347 prerequisite, see the test_set_prereq and test_have_prereq
348 documentation below:
349
350 test_expect_success TTY 'git --paginate rev-list uses a pager' \
351 ' ... '
352
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353 You can also supply a comma-separated list of prerequisites, in the
354 rare case where your test depends on more than one:
355
356 test_expect_success PERL,PYTHON 'yo dawg' \
357 ' test $(perl -E 'print eval "1 +" . qx[python -c "print 2"]') == "4" '
358
9a897893 359 - test_expect_failure [<prereq>] <message> <script>
986aa7f1 360
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361 This is NOT the opposite of test_expect_success, but is used
362 to mark a test that demonstrates a known breakage. Unlike
363 the usual test_expect_success tests, which say "ok" on
364 success and "FAIL" on failure, this will say "FIXED" on
365 success and "still broken" on failure. Failures from these
366 tests won't cause -i (immediate) to stop.
986aa7f1 367
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368 Like test_expect_success this function can optionally use a three
369 argument invocation with a prerequisite as the first argument.
370
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371 - test_expect_code [<prereq>] <code> <message> <script>
372
373 Analogous to test_expect_success, but pass the test if it exits
374 with a given exit <code>
375
376 test_expect_code 1 'Merge with d/f conflicts' 'git merge "merge msg" B master'
377
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378 - test_debug <script>
379
380 This takes a single argument, <script>, and evaluates it only
381 when the test script is started with --debug command line
382 argument. This is primarily meant for use during the
383 development of a new test script.
384
385 - test_done
386
387 Your test script must have test_done at the end. Its purpose
388 is to summarize successes and failures in the test script and
389 exit with an appropriate error code.
390
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391 - test_tick
392
393 Make commit and tag names consistent by setting the author and
394 committer times to defined stated. Subsequent calls will
395 advance the times by a fixed amount.
396
397 - test_commit <message> [<filename> [<contents>]]
398
399 Creates a commit with the given message, committing the given
400 file with the given contents (default for both is to reuse the
401 message string), and adds a tag (again reusing the message
402 string as name). Calls test_tick to make the SHA-1s
403 reproducible.
404
405 - test_merge <message> <commit-or-tag>
406
407 Merges the given rev using the given message. Like test_commit,
408 creates a tag and calls test_tick before committing.
986aa7f1 409
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410 - test_set_prereq SOME_PREREQ
411
412 Set a test prerequisite to be used later with test_have_prereq. The
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413 test-lib will set some prerequisites for you, see the
414 "Prerequisites" section below for a full list of these.
415
416 Others you can set yourself and use later with either
417 test_have_prereq directly, or the three argument invocation of
418 test_expect_success and test_expect_failure.
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419
420 - test_have_prereq SOME PREREQ
421
422 Check if we have a prerequisite previously set with
423 test_set_prereq. The most common use of this directly is to skip
424 all the tests if we don't have some essential prerequisite:
425
426 if ! test_have_prereq PERL
427 then
428 skip_all='skipping perl interface tests, perl not available'
429 test_done
430 fi
431
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432 - test_external [<prereq>] <message> <external> <script>
433
434 Execute a <script> with an <external> interpreter (like perl). This
435 was added for tests like t9700-perl-git.sh which do most of their
436 work in an external test script.
437
438 test_external \
439 'GitwebCache::*FileCache*' \
440 "$PERL_PATH" "$TEST_DIRECTORY"/t9503/test_cache_interface.pl
441
442 If the test is outputting its own TAP you should set the
443 test_external_has_tap variable somewhere before calling the first
444 test_external* function. See t9700-perl-git.sh for an example.
445
446 # The external test will outputs its own plan
447 test_external_has_tap=1
448
449 - test_external_without_stderr [<prereq>] <message> <external> <script>
450
451 Like test_external but fail if there's any output on stderr,
452 instead of checking the exit code.
453
454 test_external_without_stderr \
455 'Perl API' \
456 "$PERL_PATH" "$TEST_DIRECTORY"/t9700/test.pl
457
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458 - test_must_fail <git-command>
459
460 Run a git command and ensure it fails in a controlled way. Use
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461 this instead of "! <git-command>". When git-command dies due to a
462 segfault, test_must_fail diagnoses it as an error; "! <git-command>"
463 treats it as just another expected failure, which would let such a
464 bug go unnoticed.
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465
466 - test_might_fail <git-command>
467
468 Similar to test_must_fail, but tolerate success, too. Use this
469 instead of "<git-command> || :" to catch failures due to segv.
470
471 - test_cmp <expected> <actual>
472
473 Check whether the content of the <actual> file matches the
474 <expected> file. This behaves like "cmp" but produces more
475 helpful output when the test is run with "-v" option.
476
477 - test_when_finished <script>
478
479 Prepend <script> to a list of commands to run to clean up
480 at the end of the current test. If some clean-up command
481 fails, the test will not pass.
482
483 Example:
484
485 test_expect_success 'branch pointing to non-commit' '
486 git rev-parse HEAD^{tree} >.git/refs/heads/invalid &&
487 test_when_finished "git update-ref -d refs/heads/invalid" &&
488 ...
489 '
490
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491Prerequisites
492-------------
493
494These are the prerequisites that the test library predefines with
495test_have_prereq.
496
497See the prereq argument to the test_* functions in the "Test harness
498library" section above and the "test_have_prereq" function for how to
499use these, and "test_set_prereq" for how to define your own.
500
501 - PERL & PYTHON
502
503 Git wasn't compiled with NO_PERL=YesPlease or
504 NO_PYTHON=YesPlease. Wrap any tests that need Perl or Python in
505 these.
506
507 - POSIXPERM
508
509 The filesystem supports POSIX style permission bits.
510
511 - BSLASHPSPEC
512
513 Backslashes in pathspec are not directory separators. This is not
514 set on Windows. See 6fd1106a for details.
515
516 - EXECKEEPSPID
517
518 The process retains the same pid across exec(2). See fb9a2bea for
519 details.
520
521 - SYMLINKS
522
523 The filesystem we're on supports symbolic links. E.g. a FAT
524 filesystem doesn't support these. See 704a3143 for details.
2fac6a4b 525
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526Tips for Writing Tests
527----------------------
528
529As with any programming projects, existing programs are the best
530source of the information. However, do _not_ emulate
531t0000-basic.sh when writing your tests. The test is special in
532that it tries to validate the very core of GIT. For example, it
533knows that there will be 256 subdirectories under .git/objects/,
534and it knows that the object ID of an empty tree is a certain
53540-byte string. This is deliberately done so in t0000-basic.sh
536because the things the very basic core test tries to achieve is
537to serve as a basis for people who are changing the GIT internal
538drastically. For these people, after making certain changes,
539not seeing failures from the basic test _is_ a failure. And
540such drastic changes to the core GIT that even changes these
541otherwise supposedly stable object IDs should be accompanied by
542an update to t0000-basic.sh.
543
544However, other tests that simply rely on basic parts of the core
545GIT working properly should not have that level of intimate
546knowledge of the core GIT internals. If all the test scripts
547hardcoded the object IDs like t0000-basic.sh does, that defeats
548the purpose of t0000-basic.sh, which is to isolate that level of
549validation in one place. Your test also ends up needing
550updating when such a change to the internal happens, so do _not_
551do it and leave the low level of validation to t0000-basic.sh.