1BATS(7) Bash Automated Testing System BATS(7)
2
6 bats - Bats test file format
7
9 A Bats test file is a Bash script with special syntax for defining test
10 cases. Under the hood, each test case is just a function with a de‐
11 scription.
12 #!/usr/bin/env bats
16 @test "addition using bc" {
18 result="$(echo 2+2 | bc)"
19 [ "$result" -eq 4 ]
20 }
21 @test "addition using dc" {
23 result="$(echo 2 2+p | dc)"
24 [ "$result" -eq 4 ]
25 }
26 Each Bats test file is evaluated n+1 times, where n is the number of
30 test cases in the file. The first run counts the number of test cases,
31 then iterates over the test cases and executes each one in its own
32 process.
33
35 Usage: run [OPTIONS] [--] <command...> Options: ! check for non zero
36 exit code =N check that exit code is N --output {merged,separate,std‐
37 out,stderr} control which output is recorded --keep-empty-lines retain
38 emtpy lines in ${lines[@]}
39 Many Bats tests need to run a command and then make assertions about
41 its exit status and output. Bats includes a run helper that invokes its
42 arguments as a command, saves the exit status and output into special
43 global variables, and (optionally) checks exit status against a given
44 expected value. If successful, run returns with a 0 status code so you
45 can continue to make assertions in your test case.
46 For example, let´s say you´re testing that the foo command, when passed
48 a nonexistent filename, exits with a 1 status code and prints an error
49 message.
50 @test "invoking foo with a nonexistent file prints an error" {
54 run -1 foo nonexistent_filename
55 [ "$output" = "foo: no such file ´nonexistent_filename´" ]
56 }
57 The =1 as first argument tells run to expect 1 as an exit status, and
61 to fail if the command exits with any other value. On failure, both ac‐
62 tual and expected values will be displayed, along with the invoked com‐
63 mand and its output:
64 (in test file test.bats, line 2)
68 `run -1 foo nonexistent_filename´ failed, expected exit code 1, got 127
69 This error indicates a possible problem with the installation or con‐
73 figuration of foo; note that a simple [ $status != 0 ] test would not
74 have caught this kind of failure.
75 The $status variable contains the status code of the command, and the
77 $output variable contains the combined contents of the command´s stan‐
78 dard output and standard error streams.
79 A third special variable, the $lines array, is available for easily ac‐
81 cessing individual lines of output. For example, if you want to test
82 that invoking foo without any arguments prints usage information on the
83 first line:
84 @test "invoking foo without arguments prints usage" {
88 run -1 foo
89 [ "${lines[0]}" = "usage: foo <filename>" ]
90 }
91 By default run leaves out empty lines in ${lines[@]}. Use run
95 --keep-empty-lines to retain them.
96 Additionally, you can use run --output <mode> to control what goes into
98 $output and $lines. The available values for <mode> are:
99 • merged: the default when --output is not specified, interleaves
101 stdout and stderr
102 • separate: splits stderr off to $stderr and ${stderr_lines[@]}, std‐
104 out is still available as $output and ${lines[@]}
105 • stderr: discards stdout and fills ´$stderrand${stderr_lines[@]}`
107 • stdout: discards stdout and fills $output and ${lines[@]}
109 All additional parameters to run should come before the command. If you
113 want to run a command that starts with -, prefix it with -- to prevent
114 run from parsing it as an option.
115
117 You may want to share common code across multiple test files. Bats in‐
118 cludes a convenient load command for sourcing a Bash source file rela‐
119 tive to the location of the current test file. For example, if you have
120 a Bats test in test/foo.bats, the command
121 load test_helper
125 will source the script test/test_helper.bash in your test file. This
129 can be useful for sharing functions to set up your environment or load
130 fixtures.
131
133 Tests can be skipped by using the skip command at the point in a test
134 you wish to skip.
135 @test "A test I don´t want to execute for now" {
139 skip
140 run -0 foo
141 }
142 Optionally, you may include a reason for skipping:
146 @test "A test I don´t want to execute for now" {
150 skip "This command will return zero soon, but not now"
151 run -0 foo
152 }
153 Or you can skip conditionally:
157 @test "A test which should run" {
161 if [ foo != bar ]; then
162 skip "foo isn´t bar"
163 fi
164 run -0 foo
166 }
167
171 You can define special setup and teardown functions which run before
172 and after each test case, respectively. Use these to load fixtures, set
173 up your environment, and clean up when you´re done.
174
176 You can include code in your test file outside of @test functions. For
177 example, this may be useful if you want to check for dependencies and
178 fail immediately if they´re not present. However, any output that you
179 print in code outside of @test, setup or teardown functions must be
180 redirected to stderr (>&2). Otherwise, the output may cause Bats to
181 fail by polluting the TAP stream on stdout.
182
184 There are several global variables you can use to introspect on Bats
185 tests:
186 • $BATS_TEST_FILENAME is the fully expanded path to the Bats test
188 file.
189 • $BATS_TEST_DIRNAME is the directory in which the Bats test file is
191 located.
192 • $BATS_TEST_NAMES is an array of function names for each test case.
194 • $BATS_TEST_NAME is the name of the function containing the current
196 test case.
197 • $BATS_TEST_DESCRIPTION is the description of the current test case.
199 • $BATS_TEST_NUMBER is the (1-based) index of the current test case
201 in the test file.
202 • $BATS_SUITE_TEST_NUMBER is the (1-based) index of the current test
204 case in the test suite (over all files).
205 • $BATS_TMPDIR is the base temporary directory used by bats to create
207 its temporary files / directories. (default: $TMPDIR. If $TMPDIR is
208 not set, /tmp is used.)
209 • $BATS_RUN_TMPDIR is the location to the temporary directory used by
211 bats to store all its internal temporary files during the tests.
212 (default: $BATS_TMPDIR/bats-run-$BATS_ROOT_PID-XXXXXX)
213 • $BATS_FILE_EXTENSION (default: bats) specifies the extension of
215 test files that should be found when running a suite (via bats [-r]
216 suite_folder/)
217 • $BATS_SUITE_TMPDIR is a temporary directory common to all tests of
219 a suite. Could be used to create files required by multiple tests.
220 • $BATS_FILE_TMPDIR is a temporary directory common to all tests of a
222 test file. Could be used to create files required by multiple tests
223 in the same test file.
224 • $BATS_TEST_TMPDIR is a temporary directory unique for each test.
226 Could be used to create files required only for specific tests.
227
231 bash(1), bats(1)
232bats-core August 2021 BATS(7)