[PATCH 2/2] Test framework documentation.
[git/git.git] / t / README
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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-db in an empty repo.
22 * ok 2: .git/objects should have 256 subdirectories.
23 * ok 3: git-update-cache without --add should fail adding.
24 ...
25 * ok 23: no diff after checkout and git-update-cache --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 ./t0500-ls-files.sh
36 * ok 1: git-update-cache --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.
43
44--verbose::
45 This makes the test more verbose. Specifically, the
46 command being run and their output if any are also
47 output.
48
49--debug::
50 This may help the person who is developing a new test.
51 It causes the command defined with test_debug to run.
52
53--immediate::
54 This causes the test to immediately exit upon the first
55 failed test.
56
57
58Writing Tests
59-------------
60
61The test script is written as a shell script. It should start
62with the standard "#!/bin/sh" with copyright notices, and an
63assignment to variable 'test_description', like this:
64
65 #!/bin/sh
66 #
67 # Copyright (c) 2005 Junio C Hamano
68 #
69
70 test_description=xxx test (option --frotz)
71
72 This test registers the following structure in the cache
73 and tries to run git-ls-files with option --frotz.'
74
75Source 'test-lib.sh'
76--------------------
77
78After assigning test_description, the test script should source
79test-lib.sh like this:
80
81 . ./test-lib.sh
82
83This test harness library does the following things:
84
85 - If the script is invoked with command line argument --help
86 (or -h), it shows the test_description and exits.
87
88 - Creates an empty test directory with an empty .git/objects
89 database and chdir(2) into it. This directory is 't/trash'
90 if you must know, but I do not think you care.
91
92 - Defines standard test helper functions for your scripts to
93 use. These functions are designed to make all scripts behave
94 consistently when command line arguments --verbose (or -v),
95 --debug (or -d), and --immediate (or -i) is given.
96
97
98End with test_done
99------------------
100
101Your script will be a sequence of tests, using helper functions
102from the test harness library. At the end of the script, call
103'test_done'.
104
105
106Test harness library
107--------------------
108
109There are a handful helper functions defined in the test harness
110library for your script to use.
111
112 - test_expect_success <message> <script>
113
114 This takes two strings as parameter, and evaluates the
115 <script>. If it yields success, test is considered
116 successful. <message> should state what it is testing.
117
118 Example:
119
120 test_expect_success \
121 'git-write-tree should be able to write an empty tree.' \
122 'tree=$(git-write-tree)'
123
124 - test_expect_failure <message> <script>
125
126 This is the opposite of test_expect_success. If <script>
127 yields success, test is considered a failure.
128
129 Example:
130
131 test_expect_failure \
132 'git-update-cache without --add should fail adding.' \
133 'git-update-cache should-be-empty'
134
135 - test_debug <script>
136
137 This takes a single argument, <script>, and evaluates it only
138 when the test script is started with --debug command line
139 argument. This is primarily meant for use during the
140 development of a new test script.
141
142 - test_done
143
144 Your test script must have test_done at the end. Its purpose
145 is to summarize successes and failures in the test script and
146 exit with an appropriate error code.
147
148
149Tips for Writing Tests
150----------------------
151
152As with any programming projects, existing programs are the best
153source of the information. However, do _not_ emulate
154t0000-basic.sh when writing your tests. The test is special in
155that it tries to validate the very core of GIT. For example, it
156knows that there will be 256 subdirectories under .git/objects/,
157and it knows that the object ID of an empty tree is a certain
15840-byte string. This is deliberately done so in t0000-basic.sh
159because the things the very basic core test tries to achieve is
160to serve as a basis for people who are changing the GIT internal
161drastically. For these people, after making certain changes,
162not seeing failures from the basic test _is_ a failure. And
163such drastic changes to the core GIT that even changes these
164otherwise supposedly stable object IDs should be accompanied by
165an update to t0000-basic.sh.
166
167However, other tests that simply rely on basic parts of the core
168GIT working properly should not have that level of intimate
169knowledge of the core GIT internals. If all the test scripts
170hardcoded the object IDs like t0000-basic.sh does, that defeats
171the purpose of t0000-basic.sh, which is to isolate that level of
172validation in one place. Your test also ends up needing
173updating when such a change to the internal happens, so do _not_
174do it and leave the low level of validation to t0000-basic.sh.