[PATCH 2/2] Test framework documentation.
This adds instruction for running tests, and writing new tests. Signed-off-by: Junio C Hamano <junkio@cox.net> Updated to the new tidied up output style. Signed-off-by: Petr Baudis <pasky@ucw.cz>
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Petr Baudis
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Core GIT Tests
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==============
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This directory holds many test scripts for core GIT tools. The
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first part of this short document describes how to run the tests
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and read their output.
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When fixing the tools or adding enhancements, you are strongly
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encouraged to add tests in this directory to cover what you are
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trying to fix or enhance. The later part of this short document
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describes how your test scripts should be organized.
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Running Tests
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-------------
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The easiest way to run tests is to say "make". This runs all
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the tests.
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*** t0000-basic.sh ***
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* ok 1: .git/objects should be empty after git-init-db in an empty repo.
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* ok 2: .git/objects should have 256 subdirectories.
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* ok 3: git-update-cache without --add should fail adding.
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...
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* ok 23: no diff after checkout and git-update-cache --refresh.
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* passed all 23 test(s)
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*** t0100-environment-names.sh ***
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* ok 1: using old names should issue warnings.
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* ok 2: using old names but having new names should not issue warnings.
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...
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Or you can run each test individually from command line, like
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this:
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$ sh ./t0500-ls-files.sh
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* ok 1: git-update-cache --add to add various paths.
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* ok 2: git-ls-files -k to show killed files.
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* ok 3: validate git-ls-files -k output.
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* passed all 3 test(s)
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You can pass --verbose (or -v), --debug (or -d), and --immediate
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(or -i) command line argument to the test.
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--verbose::
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This makes the test more verbose. Specifically, the
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command being run and their output if any are also
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output.
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--debug::
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This may help the person who is developing a new test.
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It causes the command defined with test_debug to run.
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--immediate::
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This causes the test to immediately exit upon the first
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failed test.
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Writing Tests
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-------------
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The test script is written as a shell script. It should start
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with the standard "#!/bin/sh" with copyright notices, and an
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assignment to variable 'test_description', like this:
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#!/bin/sh
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#
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# Copyright (c) 2005 Junio C Hamano
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#
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test_description=xxx test (option --frotz)
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This test registers the following structure in the cache
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and tries to run git-ls-files with option --frotz.'
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Source 'test-lib.sh'
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--------------------
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After assigning test_description, the test script should source
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test-lib.sh like this:
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. ./test-lib.sh
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This test harness library does the following things:
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- If the script is invoked with command line argument --help
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(or -h), it shows the test_description and exits.
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- Creates an empty test directory with an empty .git/objects
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database and chdir(2) into it. This directory is 't/trash'
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if you must know, but I do not think you care.
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- Defines standard test helper functions for your scripts to
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use. These functions are designed to make all scripts behave
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consistently when command line arguments --verbose (or -v),
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--debug (or -d), and --immediate (or -i) is given.
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End with test_done
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------------------
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Your script will be a sequence of tests, using helper functions
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from the test harness library. At the end of the script, call
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'test_done'.
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Test harness library
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--------------------
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There are a handful helper functions defined in the test harness
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library for your script to use.
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- test_expect_success <message> <script>
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This takes two strings as parameter, and evaluates the
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<script>. If it yields success, test is considered
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successful. <message> should state what it is testing.
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Example:
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test_expect_success \
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'git-write-tree should be able to write an empty tree.' \
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'tree=$(git-write-tree)'
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- test_expect_failure <message> <script>
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This is the opposite of test_expect_success. If <script>
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yields success, test is considered a failure.
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Example:
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test_expect_failure \
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'git-update-cache without --add should fail adding.' \
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'git-update-cache should-be-empty'
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- test_debug <script>
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This takes a single argument, <script>, and evaluates it only
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when the test script is started with --debug command line
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argument. This is primarily meant for use during the
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development of a new test script.
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- test_done
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Your test script must have test_done at the end. Its purpose
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is to summarize successes and failures in the test script and
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exit with an appropriate error code.
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Tips for Writing Tests
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----------------------
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As with any programming projects, existing programs are the best
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source of the information. However, do _not_ emulate
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t0000-basic.sh when writing your tests. The test is special in
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that it tries to validate the very core of GIT. For example, it
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knows that there will be 256 subdirectories under .git/objects/,
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and it knows that the object ID of an empty tree is a certain
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40-byte string. This is deliberately done so in t0000-basic.sh
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because the things the very basic core test tries to achieve is
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to serve as a basis for people who are changing the GIT internal
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drastically. For these people, after making certain changes,
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not seeing failures from the basic test _is_ a failure. And
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such drastic changes to the core GIT that even changes these
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otherwise supposedly stable object IDs should be accompanied by
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an update to t0000-basic.sh.
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However, other tests that simply rely on basic parts of the core
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GIT working properly should not have that level of intimate
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knowledge of the core GIT internals. If all the test scripts
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hardcoded the object IDs like t0000-basic.sh does, that defeats
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the purpose of t0000-basic.sh, which is to isolate that level of
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validation in one place. Your test also ends up needing
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updating when such a change to the internal happens, so do _not_
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do it and leave the low level of validation to t0000-basic.sh.
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