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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 ***
  21    *   ok 1: .git/objects should be empty after git-init in an empty repo.
  22    *   ok 2: .git/objects should have 256 subdirectories.
  23    *   ok 3: git-update-index without --add should fail adding.
  24    ...
  25    *   ok 23: no diff after checkout and git-update-index --refresh.
  26    * passed all 23 test(s)
  27    *** t0100-environment-names.sh ***
  28    *   ok 1: using old names should issue warnings.
  29    *   ok 2: using old names but having new names should not issue warnings.
  30    ...
  31
  32Or you can run each test individually from command line, like
  33this:
  34
  35    $ sh ./t3001-ls-files-killed.sh
  36    *   ok 1: git-update-index --add to add various paths.
  37    *   ok 2: git-ls-files -k to show killed files.
  38    *   ok 3: validate git-ls-files -k output.
  39    * passed all 3 test(s)
  40
  41You can pass --verbose (or -v), --debug (or -d), and --immediate
  42(or -i) command line argument to the test, or by setting GIT_TEST_OPTS
  43appropriately before running "make".
  44
  45--verbose::
  46        This makes the test more verbose.  Specifically, the
  47        command being run and their output if any are also
  48        output.
  49
  50--debug::
  51        This may help the person who is developing a new test.
  52        It causes the command defined with test_debug to run.
  53
  54--immediate::
  55        This causes the test to immediately exit upon the first
  56        failed test.
  57
  58--long-tests::
  59        This causes additional long-running tests to be run (where
  60        available), for more exhaustive testing.
  61
  62--valgrind::
  63        Execute all Git binaries with valgrind and exit with status
  64        126 on errors (just like regular tests, this will only stop
  65        the test script when running under -i).  Valgrind errors
  66        go to stderr, so you might want to pass the -v option, too.
  67
  68        Since it makes no sense to run the tests with --valgrind and
  69        not see any output, this option implies --verbose.  For
  70        convenience, it also implies --tee.
  71
  72--tee::
  73        In addition to printing the test output to the terminal,
  74        write it to files named 't/test-results/$TEST_NAME.out'.
  75        As the names depend on the tests' file names, it is safe to
  76        run the tests with this option in parallel.
  77
  78--with-dashes::
  79        By default tests are run without dashed forms of
  80        commands (like git-commit) in the PATH (it only uses
  81        wrappers from ../bin-wrappers).  Use this option to include
  82        the build directory (..) in the PATH, which contains all
  83        the dashed forms of commands.  This option is currently
  84        implied by other options like --valgrind and
  85        GIT_TEST_INSTALLED.
  86
  87You can also set the GIT_TEST_INSTALLED environment variable to
  88the bindir of an existing git installation to test that installation.
  89You still need to have built this git sandbox, from which various
  90test-* support programs, templates, and perl libraries are used.
  91If your installed git is incomplete, it will silently test parts of
  92your built version instead.
  93
  94When using GIT_TEST_INSTALLED, you can also set GIT_TEST_EXEC_PATH to
  95override the location of the dashed-form subcommands (what
  96GIT_EXEC_PATH would be used for during normal operation).
  97GIT_TEST_EXEC_PATH defaults to `$GIT_TEST_INSTALLED/git --exec-path`.
  98
  99
 100Skipping Tests
 101--------------
 102
 103In some environments, certain tests have no way of succeeding
 104due to platform limitation, such as lack of 'unzip' program, or
 105filesystem that do not allow arbitrary sequence of non-NUL bytes
 106as pathnames.
 107
 108You should be able to say something like
 109
 110    $ GIT_SKIP_TESTS=t9200.8 sh ./t9200-git-cvsexport-commit.sh
 111
 112and even:
 113
 114    $ GIT_SKIP_TESTS='t[0-4]??? t91?? t9200.8' make
 115
 116to omit such tests.  The value of the environment variable is a
 117SP separated list of patterns that tells which tests to skip,
 118and either can match the "t[0-9]{4}" part to skip the whole
 119test, or t[0-9]{4} followed by ".$number" to say which
 120particular test to skip.
 121
 122Note that some tests in the existing test suite rely on previous
 123test item, so you cannot arbitrarily disable one and expect the
 124remainder of test to check what the test originally was intended
 125to check.
 126
 127
 128Naming Tests
 129------------
 130
 131The test files are named as:
 132
 133        tNNNN-commandname-details.sh
 134
 135where N is a decimal digit.
 136
 137First digit tells the family:
 138
 139        0 - the absolute basics and global stuff
 140        1 - the basic commands concerning database
 141        2 - the basic commands concerning the working tree
 142        3 - the other basic commands (e.g. ls-files)
 143        4 - the diff commands
 144        5 - the pull and exporting commands
 145        6 - the revision tree commands (even e.g. merge-base)
 146        7 - the porcelainish commands concerning the working tree
 147        8 - the porcelainish commands concerning forensics
 148        9 - the git tools
 149
 150Second digit tells the particular command we are testing.
 151
 152Third digit (optionally) tells the particular switch or group of switches
 153we are testing.
 154
 155If you create files under t/ directory (i.e. here) that is not
 156the top-level test script, never name the file to match the above
 157pattern.  The Makefile here considers all such files as the
 158top-level test script and tries to run all of them.  A care is
 159especially needed if you are creating a common test library
 160file, similar to test-lib.sh, because such a library file may
 161not be suitable for standalone execution.
 162
 163
 164Writing Tests
 165-------------
 166
 167The test script is written as a shell script.  It should start
 168with the standard "#!/bin/sh" with copyright notices, and an
 169assignment to variable 'test_description', like this:
 170
 171        #!/bin/sh
 172        #
 173        # Copyright (c) 2005 Junio C Hamano
 174        #
 175
 176        test_description='xxx test (option --frotz)
 177
 178        This test registers the following structure in the cache
 179        and tries to run git-ls-files with option --frotz.'
 180
 181
 182Source 'test-lib.sh'
 183--------------------
 184
 185After assigning test_description, the test script should source
 186test-lib.sh like this:
 187
 188        . ./test-lib.sh
 189
 190This test harness library does the following things:
 191
 192 - If the script is invoked with command line argument --help
 193   (or -h), it shows the test_description and exits.
 194
 195 - Creates an empty test directory with an empty .git/objects
 196   database and chdir(2) into it.  This directory is 't/trash directory'
 197   if you must know, but I do not think you care.
 198
 199 - Defines standard test helper functions for your scripts to
 200   use.  These functions are designed to make all scripts behave
 201   consistently when command line arguments --verbose (or -v),
 202   --debug (or -d), and --immediate (or -i) is given.
 203
 204
 205End with test_done
 206------------------
 207
 208Your script will be a sequence of tests, using helper functions
 209from the test harness library.  At the end of the script, call
 210'test_done'.
 211
 212
 213Test harness library
 214--------------------
 215
 216There are a handful helper functions defined in the test harness
 217library for your script to use.
 218
 219 - test_expect_success <message> <script>
 220
 221   This takes two strings as parameter, and evaluates the
 222   <script>.  If it yields success, test is considered
 223   successful.  <message> should state what it is testing.
 224
 225   Example:
 226
 227        test_expect_success \
 228            'git-write-tree should be able to write an empty tree.' \
 229            'tree=$(git-write-tree)'
 230
 231 - test_expect_failure <message> <script>
 232
 233   This is NOT the opposite of test_expect_success, but is used
 234   to mark a test that demonstrates a known breakage.  Unlike
 235   the usual test_expect_success tests, which say "ok" on
 236   success and "FAIL" on failure, this will say "FIXED" on
 237   success and "still broken" on failure.  Failures from these
 238   tests won't cause -i (immediate) to stop.
 239
 240 - test_debug <script>
 241
 242   This takes a single argument, <script>, and evaluates it only
 243   when the test script is started with --debug command line
 244   argument.  This is primarily meant for use during the
 245   development of a new test script.
 246
 247 - test_done
 248
 249   Your test script must have test_done at the end.  Its purpose
 250   is to summarize successes and failures in the test script and
 251   exit with an appropriate error code.
 252
 253 - test_tick
 254
 255   Make commit and tag names consistent by setting the author and
 256   committer times to defined stated.  Subsequent calls will
 257   advance the times by a fixed amount.
 258
 259 - test_commit <message> [<filename> [<contents>]]
 260
 261   Creates a commit with the given message, committing the given
 262   file with the given contents (default for both is to reuse the
 263   message string), and adds a tag (again reusing the message
 264   string as name).  Calls test_tick to make the SHA-1s
 265   reproducible.
 266
 267 - test_merge <message> <commit-or-tag>
 268
 269   Merges the given rev using the given message.  Like test_commit,
 270   creates a tag and calls test_tick before committing.
 271
 272Tips for Writing Tests
 273----------------------
 274
 275As with any programming projects, existing programs are the best
 276source of the information.  However, do _not_ emulate
 277t0000-basic.sh when writing your tests.  The test is special in
 278that it tries to validate the very core of GIT.  For example, it
 279knows that there will be 256 subdirectories under .git/objects/,
 280and it knows that the object ID of an empty tree is a certain
 28140-byte string.  This is deliberately done so in t0000-basic.sh
 282because the things the very basic core test tries to achieve is
 283to serve as a basis for people who are changing the GIT internal
 284drastically.  For these people, after making certain changes,
 285not seeing failures from the basic test _is_ a failure.  And
 286such drastic changes to the core GIT that even changes these
 287otherwise supposedly stable object IDs should be accompanied by
 288an update to t0000-basic.sh.
 289
 290However, other tests that simply rely on basic parts of the core
 291GIT working properly should not have that level of intimate
 292knowledge of the core GIT internals.  If all the test scripts
 293hardcoded the object IDs like t0000-basic.sh does, that defeats
 294the purpose of t0000-basic.sh, which is to isolate that level of
 295validation in one place.  Your test also ends up needing
 296updating when such a change to the internal happens, so do _not_
 297do it and leave the low level of validation to t0000-basic.sh.