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+Core Git Tests
+==============
+
+This directory holds many test scripts for core Git tools. The
+first part of this short document describes how to run the tests
+and read their output.
+
+When fixing the tools or adding enhancements, you are strongly
+encouraged to add tests in this directory to cover what you are
+trying to fix or enhance. The later part of this short document
+describes how your test scripts should be organized.
+
+
+Running Tests
+-------------
+
+The easiest way to run tests is to say "make". This runs all
+the tests.
+
+ *** t0000-basic.sh ***
+ ok 1 - .git/objects should be empty after git init in an empty repo.
+ ok 2 - .git/objects should have 3 subdirectories.
+ ok 3 - success is reported like this
+ ...
+ ok 43 - very long name in the index handled sanely
+ # fixed 1 known breakage(s)
+ # still have 1 known breakage(s)
+ # passed all remaining 42 test(s)
+ 1..43
+ *** t0001-init.sh ***
+ ok 1 - plain
+ ok 2 - plain with GIT_WORK_TREE
+ ok 3 - plain bare
+
+Since the tests all output TAP (see http://testanything.org) they can
+be run with any TAP harness. Here's an example of parallel testing
+powered by a recent version of prove(1):
+
+ $ prove --timer --jobs 15 ./t[0-9]*.sh
+ [19:17:33] ./t0005-signals.sh ................................... ok 36 ms
+ [19:17:33] ./t0022-crlf-rename.sh ............................... ok 69 ms
+ [19:17:33] ./t0024-crlf-archive.sh .............................. ok 154 ms
+ [19:17:33] ./t0004-unwritable.sh ................................ ok 289 ms
+ [19:17:33] ./t0002-gitfile.sh ................................... ok 480 ms
+ ===( 102;0 25/? 6/? 5/? 16/? 1/? 4/? 2/? 1/? 3/? 1... )===
+
+prove and other harnesses come with a lot of useful options. The
+--state option in particular is very useful:
+
+ # Repeat until no more failures
+ $ prove -j 15 --state=failed,save ./t[0-9]*.sh
+
+You can give DEFAULT_TEST_TARGET=prove on the make command (or define it
+in config.mak) to cause "make test" to run tests under prove.
+GIT_PROVE_OPTS can be used to pass additional options, e.g.
+
+ $ make DEFAULT_TEST_TARGET=prove GIT_PROVE_OPTS='--timer --jobs 16' test
+
+You can also run each test individually from command line, like this:
+
+ $ sh ./t3010-ls-files-killed-modified.sh
+ ok 1 - git update-index --add to add various paths.
+ ok 2 - git ls-files -k to show killed files.
+ ok 3 - validate git ls-files -k output.
+ ok 4 - git ls-files -m to show modified files.
+ ok 5 - validate git ls-files -m output.
+ # passed all 5 test(s)
+ 1..5
+
+You can pass --verbose (or -v), --debug (or -d), and --immediate
+(or -i) command line argument to the test, or by setting GIT_TEST_OPTS
+appropriately before running "make". Short options can be bundled, i.e.
+'-d -v' is the same as '-dv'.
+
+-v::
+--verbose::
+ This makes the test more verbose. Specifically, the
+ command being run and their output if any are also
+ output.
+
+--verbose-only=<pattern>::
+ Like --verbose, but the effect is limited to tests with
+ numbers matching <pattern>. The number matched against is
+ simply the running count of the test within the file.
+
+-x::
+ Turn on shell tracing (i.e., `set -x`) during the tests
+ themselves. Implies `--verbose`.
+ Ignored in test scripts that set the variable 'test_untraceable'
+ to a non-empty value, unless it's run with a Bash version
+ supporting BASH_XTRACEFD, i.e. v4.1 or later.
+
+-d::
+--debug::
+ This may help the person who is developing a new test.
+ It causes the command defined with test_debug to run.
+ The "trash" directory (used to store all temporary data
+ during testing) is not deleted even if there are no
+ failed tests so that you can inspect its contents after
+ the test finished.
+
+-i::
+--immediate::
+ This causes the test to immediately exit upon the first
+ failed test. Cleanup commands requested with
+ test_when_finished are not executed if the test failed,
+ in order to keep the state for inspection by the tester
+ to diagnose the bug.
+
+-l::
+--long-tests::
+ This causes additional long-running tests to be run (where
+ available), for more exhaustive testing.
+
+-r::
+--run=<test-selector>::
+ Run only the subset of tests indicated by
+ <test-selector>. See section "Skipping Tests" below for
+ <test-selector> syntax.
+
+--valgrind=<tool>::
+ Execute all Git binaries under valgrind tool <tool> and exit
+ with status 126 on errors (just like regular tests, this will
+ only stop the test script when running under -i).
+
+ Since it makes no sense to run the tests with --valgrind and
+ not see any output, this option implies --verbose. For
+ convenience, it also implies --tee.
+
+ <tool> defaults to 'memcheck', just like valgrind itself.
+ Other particularly useful choices include 'helgrind' and
+ 'drd', but you may use any tool recognized by your valgrind
+ installation.
+
+ As a special case, <tool> can be 'memcheck-fast', which uses
+ memcheck but disables --track-origins. Use this if you are
+ running tests in bulk, to see if there are _any_ memory
+ issues.
+
+ Note that memcheck is run with the option --leak-check=no,
+ as the git process is short-lived and some errors are not
+ interesting. In order to run a single command under the same
+ conditions manually, you should set GIT_VALGRIND to point to
+ the 't/valgrind/' directory and use the commands under
+ 't/valgrind/bin/'.
+
+--valgrind-only=<pattern>::
+ Like --valgrind, but the effect is limited to tests with
+ numbers matching <pattern>. The number matched against is
+ simply the running count of the test within the file.
+
+--tee::
+ In addition to printing the test output to the terminal,
+ write it to files named 't/test-results/$TEST_NAME.out'.
+ As the names depend on the tests' file names, it is safe to
+ run the tests with this option in parallel.
+
+-V::
+--verbose-log::
+ Write verbose output to the same logfile as `--tee`, but do
+ _not_ write it to stdout. Unlike `--tee --verbose`, this option
+ is safe to use when stdout is being consumed by a TAP parser
+ like `prove`. Implies `--tee` and `--verbose`.
+
+--with-dashes::
+ By default tests are run without dashed forms of
+ commands (like git-commit) in the PATH (it only uses
+ wrappers from ../bin-wrappers). Use this option to include
+ the build directory (..) in the PATH, which contains all
+ the dashed forms of commands. This option is currently
+ implied by other options like --valgrind and
+ GIT_TEST_INSTALLED.
+
+--no-bin-wrappers::
+ By default, the test suite uses the wrappers in
+ `../bin-wrappers/` to execute `git` and friends. With this option,
+ `../git` and friends are run directly. This is not recommended
+ in general, as the wrappers contain safeguards to ensure that no
+ files from an installed Git are used, but can speed up test runs
+ especially on platforms where running shell scripts is expensive
+ (most notably, Windows).
+
+--root=<directory>::
+ Create "trash" directories used to store all temporary data during
+ testing under <directory>, instead of the t/ directory.
+ Using this option with a RAM-based filesystem (such as tmpfs)
+ can massively speed up the test suite.
+
+--chain-lint::
+--no-chain-lint::
+ If --chain-lint is enabled, the test harness will check each
+ test to make sure that it properly "&&-chains" all commands (so
+ that a failure in the middle does not go unnoticed by the final
+ exit code of the test). This check is performed in addition to
+ running the tests themselves. You may also enable or disable
+ this feature by setting the GIT_TEST_CHAIN_LINT environment
+ variable to "1" or "0", respectively.
+
+--stress::
+ Run the test script repeatedly in multiple parallel jobs until
+ one of them fails. Useful for reproducing rare failures in
+ flaky tests. The number of parallel jobs is, in order of
+ precedence: the value of the GIT_TEST_STRESS_LOAD
+ environment variable, or twice the number of available
+ processors (as shown by the 'getconf' utility), or 8.
+ Implies `--verbose -x --immediate` to get the most information
+ about the failure. Note that the verbose output of each test
+ job is saved to 't/test-results/$TEST_NAME.stress-<nr>.out',
+ and only the output of the failed test job is shown on the
+ terminal. The names of the trash directories get a
+ '.stress-<nr>' suffix, and the trash directory of the failed
+ test job is renamed to end with a '.stress-failed' suffix.
+
+--stress-jobs=<N>::
+ Override the number of parallel jobs. Implies `--stress`.
+
+--stress-limit=<N>::
+ When combined with --stress run the test script repeatedly
+ this many times in each of the parallel jobs or until one of
+ them fails, whichever comes first. Implies `--stress`.
+
+You can also set the GIT_TEST_INSTALLED environment variable to
+the bindir of an existing git installation to test that installation.
+You still need to have built this git sandbox, from which various
+test-* support programs, templates, and perl libraries are used.
+If your installed git is incomplete, it will silently test parts of
+your built version instead.
+
+When using GIT_TEST_INSTALLED, you can also set GIT_TEST_EXEC_PATH to
+override the location of the dashed-form subcommands (what
+GIT_EXEC_PATH would be used for during normal operation).
+GIT_TEST_EXEC_PATH defaults to `$GIT_TEST_INSTALLED/git --exec-path`.
+
+
+Skipping Tests
+--------------
+
+In some environments, certain tests have no way of succeeding
+due to platform limitation, such as lack of 'unzip' program, or
+filesystem that do not allow arbitrary sequence of non-NUL bytes
+as pathnames.
+
+You should be able to say something like
+
+ $ GIT_SKIP_TESTS=t9200.8 sh ./t9200-git-cvsexport-commit.sh
+
+and even:
+
+ $ GIT_SKIP_TESTS='t[0-4]??? t91?? t9200.8' make
+
+to omit such tests. The value of the environment variable is a
+SP separated list of patterns that tells which tests to skip,
+and either can match the "t[0-9]{4}" part to skip the whole
+test, or t[0-9]{4} followed by ".$number" to say which
+particular test to skip.
+
+For an individual test suite --run could be used to specify that
+only some tests should be run or that some tests should be
+excluded from a run.
+
+The argument for --run, <test-selector>, is a list of description
+substrings or globs or individual test numbers or ranges with an
+optional negation prefix (of '!') that define what tests in a test
+suite to include (or exclude, if negated) in the run. A range is two
+numbers separated with a dash and matches a range of tests with both
+ends been included. You may omit the first or the second number to
+mean "from the first test" or "up to the very last test" respectively.
+
+The argument to --run is split on commas into separate strings,
+numbers, and ranges, and picks all tests that match any of the
+individual selection criteria. If the substring of the description
+text that you want to match includes a comma, use the glob character
+'?' instead. For example --run='rebase,merge?cherry-pick' would match
+on all tests that match either the glob *rebase* or the glob
+*merge?cherry-pick*.
+
+If --run starts with an unprefixed number or range the initial
+set of tests to run is empty. If the first item starts with '!'
+all the tests are added to the initial set. After initial set is
+determined every test number or range is added or excluded from
+the set one by one, from left to right.
+
+For example, to run only tests up to a specific test (21), one
+could do this:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='1-21'
+
+or this:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='-21'
+
+Common case is to run several setup tests (1, 2, 3) and then a
+specific test (21) that relies on that setup:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='1,2,3,21'
+
+or:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run=1,2,3,21
+
+or:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='-3,21'
+
+As noted above, the test set is built by going through the items
+from left to right, so this:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='1-4,!3'
+
+will run tests 1, 2, and 4. Items that come later have higher
+precedence. It means that this:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='!3,1-4'
+
+would just run tests from 1 to 4, including 3.
+
+You may use negation with ranges. The following will run all
+test in the test suite except from 7 up to 11:
+
+ $ sh ./t9200-git-cvsexport-commit.sh --run='!7-11'
+
+Sometimes there may be multiple tests with e.g. "setup" in their name
+that are needed and rather than figuring out the number for all of them
+we can just use "setup" as a substring/glob to match against the test
+description:
+
+ $ sh ./t0050-filesystem.sh --run=setup,9-11
+
+or one could select both the setup tests and the rename ones (assuming all
+relevant tests had those words in their descriptions):
+
+ $ sh ./t0050-filesystem.sh --run=setup,rename
+
+Some tests in a test suite rely on the previous tests performing
+certain actions, specifically some tests are designated as
+"setup" test, so you cannot _arbitrarily_ disable one test and
+expect the rest to function correctly.
+
+--run is mostly useful when you want to focus on a specific test
+and know what setup is needed for it. Or when you want to run
+everything up to a certain test.
+
+
+Running tests with special setups
+---------------------------------
+
+The whole test suite could be run to test some special features
+that cannot be easily covered by a few specific test cases. These
+could be enabled by running the test suite with correct GIT_TEST_
+environment set.
+
+GIT_TEST_FAIL_PREREQS=<boolean> fails all prerequisites. This is
+useful for discovering issues with the tests where say a later test
+implicitly depends on an optional earlier test.
+
+There's a "FAIL_PREREQS" prerequisite that can be used to test for
+whether this mode is active, and e.g. skip some tests that are hard to
+refactor to deal with it. The "SYMLINKS" prerequisite is currently
+excluded as so much relies on it, but this might change in the future.
+
+GIT_TEST_SPLIT_INDEX=<boolean> forces split-index mode on the whole
+test suite. Accept any boolean values that are accepted by git-config.
+
+GIT_TEST_PASSING_SANITIZE_LEAK=true skips those tests that haven't
+declared themselves as leak-free by setting
+"TEST_PASSES_SANITIZE_LEAK=true" before sourcing "test-lib.sh". This
+test mode is used by the "linux-leaks" CI target.
+
+GIT_TEST_PASSING_SANITIZE_LEAK=check checks that our
+"TEST_PASSES_SANITIZE_LEAK=true" markings are current. Rather than
+skipping those tests that haven't set "TEST_PASSES_SANITIZE_LEAK=true"
+before sourcing "test-lib.sh" this mode runs them with
+"--invert-exit-code". This is used to check that there's a one-to-one
+mapping between "TEST_PASSES_SANITIZE_LEAK=true" and those tests that
+pass under "SANITIZE=leak". This is especially useful when testing a
+series that fixes various memory leaks with "git rebase -x".
+
+GIT_TEST_SANITIZE_LEAK_LOG=true will log memory leaks to
+"test-results/$TEST_NAME.leak/trace.*" files. The logs include a
+"dedup_token" (see +"ASAN_OPTIONS=help=1 ./git") and other options to
+make logs +machine-readable.
+
+With GIT_TEST_SANITIZE_LEAK_LOG=true we'll look at the leak logs
+before exiting and exit on failure if the logs showed that we had a
+memory leak, even if the test itself would have otherwise passed. This
+allows us to catch e.g. missing &&-chaining. This is especially useful
+when combined with "GIT_TEST_PASSING_SANITIZE_LEAK", see below.
+
+GIT_TEST_PASSING_SANITIZE_LEAK=check when combined with "--immediate"
+will run to completion faster, and result in the same failing
+tests. The only practical reason to run
+GIT_TEST_PASSING_SANITIZE_LEAK=check without "--immediate" is to
+combine it with "GIT_TEST_SANITIZE_LEAK_LOG=true". If we stop at the
+first failing test case our leak logs won't show subsequent leaks we
+might have run into.
+
+GIT_TEST_PASSING_SANITIZE_LEAK=(true|check) will not catch all memory
+leaks unless combined with GIT_TEST_SANITIZE_LEAK_LOG=true. Some tests
+run "git" (or "test-tool" etc.) without properly checking the exit
+code, or git will invoke itself and fail to ferry the abort() exit
+code to the original caller. When the two modes are combined we'll
+look at the "test-results/$TEST_NAME.leak/trace.*" files at the end of
+the test run to see if had memory leaks which the test itself didn't
+catch.
+
+GIT_TEST_PROTOCOL_VERSION=<n>, when set, makes 'protocol.version'
+default to n.
+
+GIT_TEST_FULL_IN_PACK_ARRAY=<boolean> exercises the uncommon
+pack-objects code path where there are more than 1024 packs even if
+the actual number of packs in repository is below this limit. Accept
+any boolean values that are accepted by git-config.
+
+GIT_TEST_OE_SIZE=<n> exercises the uncommon pack-objects code path
+where we do not cache object size in memory and read it from existing
+packs on demand. This normally only happens when the object size is
+over 2GB. This variable forces the code path on any object larger than
+<n> bytes.
+
+GIT_TEST_OE_DELTA_SIZE=<n> exercises the uncommon pack-objects code
+path where deltas larger than this limit require extra memory
+allocation for bookkeeping.
+
+GIT_TEST_VALIDATE_INDEX_CACHE_ENTRIES=<boolean> checks that cache-tree
+records are valid when the index is written out or after a merge. This
+is mostly to catch missing invalidation. Default is true.
+
+GIT_TEST_COMMIT_GRAPH=<boolean>, when true, forces the commit-graph to
+be written after every 'git commit' command, and overrides the
+'core.commitGraph' setting to true.
+
+GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=<boolean>, when true, forces
+commit-graph write to compute and write changed path Bloom filters for
+every 'git commit-graph write', as if the `--changed-paths` option was
+passed in.
+
+GIT_TEST_FSMONITOR=$PWD/t7519/fsmonitor-all exercises the fsmonitor
+code paths for utilizing a (hook based) file system monitor to speed up
+detecting new or changed files.
+
+GIT_TEST_INDEX_VERSION=<n> exercises the index read/write code path
+for the index version specified. Can be set to any valid version
+(currently 2, 3, or 4).
+
+GIT_TEST_PACK_SPARSE=<boolean> if disabled will default the pack-objects
+builtin to use the non-sparse object walk. This can still be overridden by
+the --sparse command-line argument.
+
+GIT_TEST_PRELOAD_INDEX=<boolean> exercises the preload-index code path
+by overriding the minimum number of cache entries required per thread.
+
+GIT_TEST_ADD_I_USE_BUILTIN=<boolean>, when false, disables the
+built-in version of git add -i. See 'add.interactive.useBuiltin' in
+git-config(1).
+
+GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading
+of the index for the whole test suite by bypassing the default number of
+cache entries and thread minimums. Setting this to 1 will make the
+index loading single threaded.
+
+GIT_TEST_MULTI_PACK_INDEX=<boolean>, when true, forces the multi-pack-
+index to be written after every 'git repack' command, and overrides the
+'core.multiPackIndex' setting to true.
+
+GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=<boolean>, when true, sets the
+'--bitmap' option on all invocations of 'git multi-pack-index write',
+and ignores pack-objects' '--write-bitmap-index'.
+
+GIT_TEST_SIDEBAND_ALL=<boolean>, when true, overrides the
+'uploadpack.allowSidebandAll' setting to true, and when false, forces
+fetch-pack to not request sideband-all (even if the server advertises
+sideband-all).
+
+GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS=<boolean>, when true (which is
+the default when running tests), errors out when an abbreviated option
+is used.
+
+GIT_TEST_DEFAULT_HASH=<hash-algo> specifies which hash algorithm to
+use in the test scripts. Recognized values for <hash-algo> are "sha1"
+and "sha256".
+
+GIT_TEST_WRITE_REV_INDEX=<boolean>, when true enables the
+'pack.writeReverseIndex' setting.
+
+GIT_TEST_SPARSE_INDEX=<boolean>, when true enables index writes to use the
+sparse-index format by default.
+
+GIT_TEST_CHECKOUT_WORKERS=<n> overrides the 'checkout.workers' setting
+to <n> and 'checkout.thresholdForParallelism' to 0, forcing the
+execution of the parallel-checkout code.
+
+GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB=<boolean>, when true, makes
+registering submodule ODBs as alternates a fatal action. Support for
+this environment variable can be removed once the migration to
+explicitly providing repositories when accessing submodule objects is
+complete or needs to be abandoned for whatever reason (in which case the
+migrated codepaths still retain their performance benefits).
+
+GIT_TEST_REQUIRE_PREREQ=<list> allows specifying a space separated list of
+prereqs that are required to succeed. If a prereq in this list is triggered by
+a test and then fails then the whole test run will abort. This can help to make
+sure the expected tests are executed and not silently skipped when their
+dependency breaks or is simply not present in a new environment.
+
+Naming Tests
+------------
+
+The test files are named as:
+
+ tNNNN-commandname-details.sh
+
+where N is a decimal digit.
+
+First digit tells the family:
+
+ 0 - the absolute basics and global stuff
+ 1 - the basic commands concerning database
+ 2 - the basic commands concerning the working tree
+ 3 - the other basic commands (e.g. ls-files)
+ 4 - the diff commands
+ 5 - the pull and exporting commands
+ 6 - the revision tree commands (even e.g. merge-base)
+ 7 - the porcelainish commands concerning the working tree
+ 8 - the porcelainish commands concerning forensics
+ 9 - the git tools
+
+Second digit tells the particular command we are testing.
+
+Third digit (optionally) tells the particular switch or group of switches
+we are testing.
+
+If you create files under t/ directory (i.e. here) that is not
+the top-level test script, never name the file to match the above
+pattern. The Makefile here considers all such files as the
+top-level test script and tries to run all of them. Care is
+especially needed if you are creating a common test library
+file, similar to test-lib.sh, because such a library file may
+not be suitable for standalone execution.
+
+
+Writing Tests
+-------------
+
+The test script is written as a shell script. It should start
+with the standard "#!/bin/sh", and an
+assignment to variable 'test_description', like this:
+
+ #!/bin/sh
+
+ test_description='xxx test (option --frotz)
+
+ This test registers the following structure in the cache
+ and tries to run git-ls-files with option --frotz.'
+
+
+Source 'test-lib.sh'
+--------------------
+
+After assigning test_description, the test script should source
+test-lib.sh like this:
+
+ . ./test-lib.sh
+
+This test harness library does the following things:
+
+ - If the script is invoked with command line argument --help
+ (or -h), it shows the test_description and exits.
+
+ - Creates an empty test directory with an empty .git/objects database
+ and chdir(2) into it. This directory is 't/trash
+ directory.$test_name_without_dotsh', with t/ subject to change by
+ the --root option documented above, and a '.stress-<N>' suffix
+ appended by the --stress option.
+
+ - Defines standard test helper functions for your scripts to
+ use. These functions are designed to make all scripts behave
+ consistently when command line arguments --verbose (or -v),
+ --debug (or -d), and --immediate (or -i) is given.
+
+Recommended style
+-----------------
+Here are some recommented styles when writing test case.
+
+ - Keep test title the same line with test helper function itself.
+
+ Take test_expect_success helper for example, write it like:
+
+ test_expect_success 'test title' '
+ ... test body ...
+ '
+
+ Instead of:
+
+ test_expect_success \
+ 'test title' \
+ '... test body ...'
+
+
+ - End the line with a single quote.
+
+ - Indent the body of here-document, and use "<<-" instead of "<<"
+ to strip leading TABs used for indentation:
+
+ test_expect_success 'test something' '
+ cat >expect <<-\EOF &&
+ one
+ two
+ three
+ EOF
+ test_something > actual &&
+ test_cmp expect actual
+ '
+
+ Instead of:
+
+ test_expect_success 'test something' '
+ cat >expect <<\EOF &&
+ one
+ two
+ three
+ EOF
+ test_something > actual &&
+ test_cmp expect actual
+ '
+
+ - Quote or escape the EOF delimiter that begins a here-document if
+ there is no parameter and other expansion in it, to signal readers
+ that they can skim it more casually:
+
+ cmd <<-\EOF
+ literal here-document text without any expansion
+ EOF
+
+
+Do's & don'ts
+-------------
+
+Here are a few examples of things you probably should and shouldn't do
+when writing tests.
+
+Here are the "do's:"
+
+ - Put all code inside test_expect_success and other assertions.
+
+ Even code that isn't a test per se, but merely some setup code
+ should be inside a test assertion.
+
+ - Chain your test assertions
+
+ Write test code like this:
+
+ git merge foo &&
+ git push bar &&
+ test ...
+
+ Instead of:
+
+ git merge hla
+ git push gh
+ test ...
+
+ That way all of the commands in your tests will succeed or fail. If
+ you must ignore the return value of something, consider using a
+ helper function (e.g. use sane_unset instead of unset, in order
+ to avoid unportable return value for unsetting a variable that was
+ already unset), or prepending the command with test_might_fail or
+ test_must_fail.
+
+ - Check the test coverage for your tests. See the "Test coverage"
+ below.
+
+ Don't blindly follow test coverage metrics; if a new function you added
+ doesn't have any coverage, then you're probably doing something wrong,
+ but having 100% coverage doesn't necessarily mean that you tested
+ everything.
+
+ Tests that are likely to smoke out future regressions are better
+ than tests that just inflate the coverage metrics.
+
+ - When a test checks for an absolute path that a git command generated,
+ construct the expected value using $(pwd) rather than $PWD,
+ $TEST_DIRECTORY, or $TRASH_DIRECTORY. It makes a difference on
+ Windows, where the shell (MSYS bash) mangles absolute path names.
+ For details, see the commit message of 4114156ae9.
+
+ - Remember that inside the <script> part, the standard output and
+ standard error streams are discarded, and the test harness only
+ reports "ok" or "not ok" to the end user running the tests. Under
+ --verbose, they are shown to help debug the tests.
+
+ - Be careful when you loop
+
+ You may need to verify multiple things in a loop, but the
+ following does not work correctly:
+
+ test_expect_success 'test three things' '
+ for i in one two three
+ do
+ test_something "$i"
+ done &&
+ test_something_else
+ '
+
+ Because the status of the loop itself is the exit status of the
+ test_something in the last round, the loop does not fail when
+ "test_something" for "one" or "two" fails. This is not what you
+ want.
+
+ Instead, you can break out of the loop immediately when you see a
+ failure. Because all test_expect_* snippets are executed inside
+ a function, "return 1" can be used to fail the test immediately
+ upon a failure:
+
+ test_expect_success 'test three things' '
+ for i in one two three
+ do
+ test_something "$i" || return 1
+ done &&
+ test_something_else
+ '
+
+ Note that we still &&-chain the loop to propagate failures from
+ earlier commands.
+
+
+And here are the "don'ts:"
+
+ - Don't exit() within a <script> part.
+
+ The harness will catch this as a programming error of the test.
+ Use test_done instead if you need to stop the tests early (see
+ "Skipping tests" below).
+
+ - Don't use '! git cmd' when you want to make sure the git command
+ exits with failure in a controlled way by calling "die()". Instead,
+ use 'test_must_fail git cmd'. This will signal a failure if git
+ dies in an unexpected way (e.g. segfault).
+
+ On the other hand, don't use test_must_fail for running regular
+ platform commands; just use '! cmd'. We are not in the business
+ of verifying that the world given to us sanely works.
+
+ - Don't feed the output of a git command to a pipe, as in:
+
+ git -C repo ls-files |
+ xargs -n 1 basename |
+ grep foo
+
+ which will discard git's exit code and may mask a crash. In the
+ above example, all exit codes are ignored except grep's.
+
+ Instead, write the output of that command to a temporary
+ file with ">" or assign it to a variable with "x=$(git ...)" rather
+ than pipe it.
+
+ - Don't use command substitution in a way that discards git's exit
+ code. When assigning to a variable, the exit code is not discarded,
+ e.g.:
+
+ x=$(git cat-file -p $sha) &&
+ ...
+
+ is OK because a crash in "git cat-file" will cause the "&&" chain
+ to fail, but:
+
+ test "refs/heads/foo" = "$(git symbolic-ref HEAD)"
+
+ is not OK and a crash in git could go undetected.
+
+ - Don't use perl without spelling it as "$PERL_PATH". This is to help
+ our friends on Windows where the platform Perl often adds CR before
+ the end of line, and they bundle Git with a version of Perl that
+ does not do so, whose path is specified with $PERL_PATH. Note that we
+ provide a "perl" function which uses $PERL_PATH under the hood, so
+ you do not need to worry when simply running perl in the test scripts
+ (but you do, for example, on a shebang line or in a sub script
+ created via "write_script").
+
+ - Don't use sh without spelling it as "$SHELL_PATH", when the script
+ can be misinterpreted by broken platform shell (e.g. Solaris).
+
+ - Don't chdir around in tests. It is not sufficient to chdir to
+ somewhere and then chdir back to the original location later in
+ the test, as any intermediate step can fail and abort the test,
+ causing the next test to start in an unexpected directory. Do so
+ inside a subshell if necessary.
+
+ - Don't save and verify the standard error of compound commands, i.e.
+ group commands, subshells, and shell functions (except test helper
+ functions like 'test_must_fail') like this:
+
+ ( cd dir && git cmd ) 2>error &&
+ test_cmp expect error
+
+ When running the test with '-x' tracing, then the trace of commands
+ executed in the compound command will be included in standard error
+ as well, quite possibly throwing off the subsequent checks examining
+ the output. Instead, save only the relevant git command's standard
+ error:
+
+ ( cd dir && git cmd 2>../error ) &&
+ test_cmp expect error
+
+ - Don't break the TAP output
+
+ The raw output from your test may be interpreted by a TAP harness. TAP
+ harnesses will ignore everything they don't know about, but don't step
+ on their toes in these areas:
+
+ - Don't print lines like "$x..$y" where $x and $y are integers.
+
+ - Don't print lines that begin with "ok" or "not ok".
+
+ TAP harnesses expect a line that begins with either "ok" and "not
+ ok" to signal a test passed or failed (and our harness already
+ produces such lines), so your script shouldn't emit such lines to
+ their output.
+
+ You can glean some further possible issues from the TAP grammar
+ (see https://metacpan.org/pod/TAP::Parser::Grammar#TAP-GRAMMAR)
+ but the best indication is to just run the tests with prove(1),
+ it'll complain if anything is amiss.
+
+
+Skipping tests
+--------------
+
+If you need to skip tests you should do so by using the three-arg form
+of the test_* functions (see the "Test harness library" section
+below), e.g.:
+
+ test_expect_success PERL 'I need Perl' '
+ perl -e "hlagh() if unf_unf()"
+ '
+
+The advantage of skipping tests like this is that platforms that don't
+have the PERL and other optional dependencies get an indication of how
+many tests they're missing.
+
+If the test code is too hairy for that (i.e. does a lot of setup work
+outside test assertions) you can also skip all remaining tests by
+setting skip_all and immediately call test_done:
+
+ if ! test_have_prereq PERL
+ then
+ skip_all='skipping perl interface tests, perl not available'
+ test_done
+ fi
+
+The string you give to skip_all will be used as an explanation for why
+the test was skipped.
+
+End with test_done
+------------------
+
+Your script will be a sequence of tests, using helper functions
+from the test harness library. At the end of the script, call
+'test_done'.
+
+
+Test harness library
+--------------------
+
+There are a handful helper functions defined in the test harness
+library for your script to use. Some of them are listed below;
+see test-lib-functions.sh for the full list and their options.
+
+ - test_expect_success [<prereq>] <message> <script>
+
+ Usually takes two strings as parameters, and evaluates the
+ <script>. If it yields success, test is considered
+ successful. <message> should state what it is testing.
+
+ Example:
+
+ test_expect_success \
+ 'git-write-tree should be able to write an empty tree.' \
+ 'tree=$(git-write-tree)'
+
+ If you supply three parameters the first will be taken to be a
+ prerequisite; see the test_set_prereq and test_have_prereq
+ documentation below:
+
+ test_expect_success TTY 'git --paginate rev-list uses a pager' \
+ ' ... '
+
+ You can also supply a comma-separated list of prerequisites, in the
+ rare case where your test depends on more than one:
+
+ test_expect_success PERL,PYTHON 'yo dawg' \
+ ' test $(perl -E 'print eval "1 +" . qx[python -c "print 2"]') == "4" '
+
+ - test_expect_failure [<prereq>] <message> <script>
+
+ This is NOT the opposite of test_expect_success, but is used
+ to mark a test that demonstrates a known breakage. Unlike
+ the usual test_expect_success tests, which say "ok" on
+ success and "FAIL" on failure, this will say "FIXED" on
+ success and "still broken" on failure. Failures from these
+ tests won't cause -i (immediate) to stop.
+
+ Like test_expect_success this function can optionally use a three
+ argument invocation with a prerequisite as the first argument.
+
+ - test_debug <script>
+
+ This takes a single argument, <script>, and evaluates it only
+ when the test script is started with --debug command line
+ argument. This is primarily meant for use during the
+ development of a new test script.
+
+ - debug [options] <git-command>
+
+ Run a git command inside a debugger. This is primarily meant for
+ use when debugging a failing test script. With '-t', use your
+ original TERM instead of test-lib.sh's "dumb", so that your
+ debugger interface has colors.
+
+ - test_done
+
+ Your test script must have test_done at the end. Its purpose
+ is to summarize successes and failures in the test script and
+ exit with an appropriate error code.
+
+ - test_tick
+
+ Make commit and tag names consistent by setting the author and
+ committer times to defined state. Subsequent calls will
+ advance the times by a fixed amount.
+
+ - test_commit <message> [<filename> [<contents>]]
+
+ Creates a commit with the given message, committing the given
+ file with the given contents (default for both is to reuse the
+ message string), and adds a tag (again reusing the message
+ string as name). Calls test_tick to make the SHA-1s
+ reproducible.
+
+ - test_merge <message> <commit-or-tag>
+
+ Merges the given rev using the given message. Like test_commit,
+ creates a tag and calls test_tick before committing.
+
+ - test_set_prereq <prereq>
+
+ Set a test prerequisite to be used later with test_have_prereq. The
+ test-lib will set some prerequisites for you, see the
+ "Prerequisites" section below for a full list of these.
+
+ Others you can set yourself and use later with either
+ test_have_prereq directly, or the three argument invocation of
+ test_expect_success and test_expect_failure.
+
+ - test_have_prereq <prereq>
+
+ Check if we have a prerequisite previously set with test_set_prereq.
+ The most common way to use this explicitly (as opposed to the
+ implicit use when an argument is passed to test_expect_*) is to skip
+ all the tests at the start of the test script if we don't have some
+ essential prerequisite:
+
+ if ! test_have_prereq PERL
+ then
+ skip_all='skipping perl interface tests, perl not available'
+ test_done
+ fi
+
+ - test_expect_code <exit-code> <command>
+
+ Run a command and ensure that it exits with the given exit code.
+ For example:
+
+ test_expect_success 'Merge with d/f conflicts' '
+ test_expect_code 1 git merge "merge msg" B master
+ '
+
+ - test_must_fail [<options>] <git-command>
+
+ Run a git command and ensure it fails in a controlled way. Use
+ this instead of "! <git-command>". When git-command dies due to a
+ segfault, test_must_fail diagnoses it as an error; "! <git-command>"
+ treats it as just another expected failure, which would let such a
+ bug go unnoticed.
+
+ Accepts the following options:
+
+ ok=<signal-name>[,<...>]:
+ Don't treat an exit caused by the given signal as error.
+ Multiple signals can be specified as a comma separated list.
+ Currently recognized signal names are: sigpipe, success.
+ (Don't use 'success', use 'test_might_fail' instead.)
+
+ - test_might_fail [<options>] <git-command>
+
+ Similar to test_must_fail, but tolerate success, too. Use this
+ instead of "<git-command> || :" to catch failures due to segv.
+
+ Accepts the same options as test_must_fail.
+
+ - test_cmp <expected> <actual>
+
+ Check whether the content of the <actual> file matches the
+ <expected> file. This behaves like "cmp" but produces more
+ helpful output when the test is run with "-v" option.
+
+ - test_cmp_rev <expected> <actual>
+
+ Check whether the <expected> rev points to the same commit as the
+ <actual> rev.
+
+ - test_line_count (= | -lt | -ge | ...) <length> <file>
+
+ Check whether a file has the length it is expected to.
+
+ - test_path_is_file <path>
+ test_path_is_dir <path>
+ test_path_is_missing <path>
+
+ Check if the named path is a file, if the named path is a
+ directory, or if the named path does not exist, respectively,
+ and fail otherwise.
+
+ - test_when_finished <script>
+
+ Prepend <script> to a list of commands to run to clean up
+ at the end of the current test. If some clean-up command
+ fails, the test will not pass.
+
+ Example:
+
+ test_expect_success 'branch pointing to non-commit' '
+ git rev-parse HEAD^{tree} >.git/refs/heads/invalid &&
+ test_when_finished "git update-ref -d refs/heads/invalid" &&
+ ...
+ '
+
+ - test_atexit <script>
+
+ Prepend <script> to a list of commands to run unconditionally to
+ clean up before the test script exits, e.g. to stop a daemon:
+
+ test_expect_success 'test git daemon' '
+ git daemon &
+ daemon_pid=$! &&
+ test_atexit 'kill $daemon_pid' &&
+ hello world
+ '
+
+ The commands will be executed before the trash directory is removed,
+ i.e. the atexit commands will still be able to access any pidfiles or
+ socket files.
+
+ Note that these commands will be run even when a test script run
+ with '--immediate' fails. Be careful with your atexit commands to
+ minimize any changes to the failed state.
+
+ - test_write_lines <lines>
+
+ Write <lines> on standard output, one line per argument.
+ Useful to prepare multi-line files in a compact form.
+
+ Example:
+
+ test_write_lines a b c d e f g >foo
+
+ Is a more compact equivalent of:
+ cat >foo <<-EOF
+ a
+ b
+ c
+ d
+ e
+ f
+ g
+ EOF
+
+
+ - test_pause [options]
+
+ This command is useful for writing and debugging tests and must be
+ removed before submitting. It halts the execution of the test and
+ spawns a shell in the trash directory. Exit the shell to continue
+ the test. Example:
+
+ test_expect_success 'test' '
+ git do-something >actual &&
+ test_pause &&
+ test_cmp expected actual
+ '
+
+ - test_ln_s_add <path1> <path2>
+
+ This function helps systems whose filesystem does not support symbolic
+ links. Use it to add a symbolic link entry to the index when it is not
+ important that the file system entry is a symbolic link, i.e., instead
+ of the sequence
+
+ ln -s foo bar &&
+ git add bar
+
+ Sometimes it is possible to split a test in a part that does not need
+ the symbolic link in the file system and a part that does; then only
+ the latter part need be protected by a SYMLINKS prerequisite (see below).
+
+ - test_oid_init
+
+ This function loads facts and useful object IDs related to the hash
+ algorithm(s) in use from the files in t/oid-info.
+
+ - test_oid_cache
+
+ This function reads per-hash algorithm information from standard
+ input (usually a heredoc) in the format described in
+ t/oid-info/README. This is useful for test-specific values, such as
+ object IDs, which must vary based on the hash algorithm.
+
+ Certain fixed values, such as hash sizes and common placeholder
+ object IDs, can be loaded with test_oid_init (described above).
+
+ - test_oid <key>
+
+ This function looks up a value for the hash algorithm in use, based
+ on the key given. The value must have been loaded using
+ test_oid_init or test_oid_cache. Providing an unknown key is an
+ error.
+
+ - yes [<string>]
+
+ This is often seen in modern UNIX but some platforms lack it, so
+ the test harness overrides the platform implementation with a
+ more limited one. Use this only when feeding a handful lines of
+ output to the downstream---unlike the real version, it generates
+ only up to 99 lines.
+
+ - test_bool_env <env-variable-name> <default-value>
+
+ Given the name of an environment variable with a bool value,
+ normalize its value to a 0 (true) or 1 (false or empty string)
+ return code. Return with code corresponding to the given default
+ value if the variable is unset.
+ Abort the test script if either the value of the variable or the
+ default are not valid bool values.
+
+
+Prerequisites
+-------------
+
+These are the prerequisites that the test library predefines with
+test_have_prereq.
+
+See the prereq argument to the test_* functions in the "Test harness
+library" section above and the "test_have_prereq" function for how to
+use these, and "test_set_prereq" for how to define your own.
+
+ - PYTHON
+
+ Git wasn't compiled with NO_PYTHON=YesPlease. Wrap any tests that
+ need Python with this.
+
+ - PERL
+
+ Git wasn't compiled with NO_PERL=YesPlease.
+
+ Even without the PERL prerequisite, tests can assume there is a
+ usable perl interpreter at $PERL_PATH, though it need not be
+ particularly modern.
+
+ - POSIXPERM
+
+ The filesystem supports POSIX style permission bits.
+
+ - BSLASHPSPEC
+
+ Backslashes in pathspec are not directory separators. This is not
+ set on Windows. See 6fd1106a for details.
+
+ - EXECKEEPSPID
+
+ The process retains the same pid across exec(2). See fb9a2bea for
+ details.
+
+ - PIPE
+
+ The filesystem we're on supports creation of FIFOs (named pipes)
+ via mkfifo(1).
+
+ - SYMLINKS
+
+ The filesystem we're on supports symbolic links. E.g. a FAT
+ filesystem doesn't support these. See 704a3143 for details.
+
+ - SANITY
+
+ Test is not run by root user, and an attempt to write to an
+ unwritable file is expected to fail correctly.
+
+ - PCRE
+
+ Git was compiled with support for PCRE. Wrap any tests
+ that use git-grep --perl-regexp or git-grep -P in these.
+
+ - CASE_INSENSITIVE_FS
+
+ Test is run on a case insensitive file system.
+
+ - UTF8_NFD_TO_NFC
+
+ Test is run on a filesystem which converts decomposed utf-8 (nfd)
+ to precomposed utf-8 (nfc).
+
+ - PTHREADS
+
+ Git wasn't compiled with NO_PTHREADS=YesPlease.
+
+ - REFFILES
+
+ Test is specific to packed/loose ref storage, and should be
+ disabled for other ref storage backends
+
+
+Tips for Writing Tests
+----------------------
+
+As with any programming projects, existing programs are the best
+source of the information. However, do _not_ emulate
+t0000-basic.sh when writing your tests. The test is special in
+that it tries to validate the very core of Git. For example, it
+knows that there will be 256 subdirectories under .git/objects/,
+and it knows that the object ID of an empty tree is a certain
+40-byte string. This is deliberately done so in t0000-basic.sh
+because the things the very basic core test tries to achieve is
+to serve as a basis for people who are changing the Git internals
+drastically. For these people, after making certain changes,
+not seeing failures from the basic test _is_ a failure. And
+such drastic changes to the core Git that even changes these
+otherwise supposedly stable object IDs should be accompanied by
+an update to t0000-basic.sh.
+
+However, other tests that simply rely on basic parts of the core
+Git working properly should not have that level of intimate
+knowledge of the core Git internals. If all the test scripts
+hardcoded the object IDs like t0000-basic.sh does, that defeats
+the purpose of t0000-basic.sh, which is to isolate that level of
+validation in one place. Your test also ends up needing
+updating when such a change to the internal happens, so do _not_
+do it and leave the low level of validation to t0000-basic.sh.
+
+Test coverage
+-------------
+
+You can use the coverage tests to find code paths that are not being
+used or properly exercised yet.
+
+To do that, run the coverage target at the top-level (not in the t/
+directory):
+
+ make coverage
+
+That'll compile Git with GCC's coverage arguments, and generate a test
+report with gcov after the tests finish. Running the coverage tests
+can take a while, since running the tests in parallel is incompatible
+with GCC's coverage mode.
+
+After the tests have run you can generate a list of untested
+functions:
+
+ make coverage-untested-functions
+
+You can also generate a detailed per-file HTML report using the
+Devel::Cover module. To install it do:
+
+ # On Debian or Ubuntu:
+ sudo aptitude install libdevel-cover-perl
+
+ # From the CPAN with cpanminus
+ curl -L http://cpanmin.us | perl - --sudo --self-upgrade
+ cpanm --sudo Devel::Cover
+
+Then, at the top-level:
+
+ make cover_db_html
+
+That'll generate a detailed cover report in the "cover_db_html"
+directory, which you can then copy to a webserver, or inspect locally
+in a browser.