NAME¶
bats - Bats test file format
DESCRIPTION¶
A Bats test file is a Bash script with special syntax for defining test cases.
Under the hood, each test case is just a function with a description.
-
-
#!/usr/bin/env bats
@test "addition using bc" {
result="$(echo 2+2 | bc)"
[ "$result" -eq 4 ]
}
@test "addition using dc" {
result="$(echo 2 2+p | dc)"
[ "$result" -eq 4 ]
}
-
Each Bats test file is evaluated n+1 times, where
n is the number of test
cases in the file. The first run counts the number of test cases, then
iterates over the test cases and executes each one in its own process.
THE RUN HELPER¶
Many Bats tests need to run a command and then make assertions about its exit
status and output. Bats includes a
run helper that invokes its
arguments as a command, saves the exit status and output into special global
variables, and then returns with a
0 status code so you can continue to
make assertions in your test case.
For example, let´s say you´re testing that the
foo command,
when passed a nonexistent filename, exits with a
1 status code and
prints an error message.
-
-
@test "invoking foo with a nonexistent file prints an error" {
run foo nonexistent_filename
[ "$status" -eq 1 ]
[ "$output" = "foo: no such file ´nonexistent_filename´" ]
}
-
The
$status variable contains the status code of the command, and the
$output variable contains the combined contents of the command´s
standard output and standard error streams.
A third special variable, the
$lines array, is available for easily
accessing individual lines of output. For example, if you want to test that
invoking
foo without any arguments prints usage information on the
first line:
-
-
@test "invoking foo without arguments prints usage" {
run foo
[ "$status" -eq 1 ]
[ "${lines[0]}" = "usage: foo <filename>" ]
}
-
THE LOAD COMMAND¶
You may want to share common code across multiple test files. Bats includes a
convenient
load command for sourcing a Bash source file relative to the
location of the current test file. For example, if you have a Bats test in
test/foo.bats, the command
-
-
load test_helper
-
will source the script
test/test_helper.bash in your test file. This can
be useful for sharing functions to set up your environment or load fixtures.
THE SKIP COMMAND¶
Tests can be skipped by using the
skip command at the point in a test you
wish to skip.
-
-
@test "A test I don´t want to execute for now" {
skip
run foo
[ "$status" -eq 0 ]
}
-
Optionally, you may include a reason for skipping:
-
-
@test "A test I don´t want to execute for now" {
skip "This command will return zero soon, but not now"
run foo
[ "$status" -eq 0 ]
}
-
Or you can skip conditionally:
-
-
@test "A test which should run" {
if [ foo != bar ]; then
skip "foo isn´t bar"
fi
run foo
[ "$status" -eq 0 ]
}
-
SETUP AND TEARDOWN FUNCTIONS¶
You can define special
setup and
teardown functions which run
before and after each test case, respectively. Use these to load fixtures, set
up your environment, and clean up when you´re done.
CODE OUTSIDE OF TEST CASES¶
You can include code in your test file outside of
@test functions. For
example, this may be useful if you want to check for dependencies and fail
immediately if they´re not present. However, any output that you print
in code outside of
@test,
setup or
teardown functions
must be redirected to
stderr (
>&2). Otherwise, the output
may cause Bats to fail by polluting the TAP stream on
stdout.
SPECIAL VARIABLES¶
There are several global variables you can use to introspect on Bats tests:
- •
- $BATS_TEST_FILENAME is the fully expanded path to the Bats test
file.
- •
- $BATS_TEST_DIRNAME is the directory in which the Bats test file is
located.
- •
- $BATS_TEST_NAMES is an array of function names for each test
case.
- •
- $BATS_TEST_NAME is the name of the function containing the current
test case.
- •
- $BATS_TEST_DESCRIPTION is the description of the current test
case.
- •
- $BATS_TEST_NUMBER is the (1-based) index of the current test case
in the test file.
- •
- $BATS_TMPDIR is the location to a directory that may be used to
store temporary files.
-
SEE ALSO¶
bash(1),
bats(1)