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BATS(1) Bash Automated Testing System BATS(1)


bats - Bash Automated Testing System


Usage: bats [OPTIONS] tests bats [-h | -v]

tests is the path to a Bats test file, or the path to a directory containing Bats test files (ending with ".bats")


Bats is a TAP-compliant testing framework for Bash. It provides a simple way to verify that the UNIX programs you write behave as expected.

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.

Test cases consist of standard shell commands. Bats makes use of Bash´s errexit (set -e) option when running test cases. If every command in the test case exits with a 0 status code (success), the test passes. In this way, each line is an assertion of truth.

See bats(7) for more information on writing Bats tests.


To run your tests, invoke the bats interpreter with a path to a test file. The file´s test cases are run sequentially and in isolation. If all the test cases pass, bats exits with a 0 status code. If there are any failures, bats exits with a 1 status code.

You can invoke the bats interpreter with multiple test file arguments, or with a path to a directory containing multiple .bats files. Bats will run each test file individually and aggregate the results. If any test case fails, bats exits with a 1 status code.


There are multiple mechanisms to filter which tests to execute:

--filter <regex> to filter by test name
--filter-status <status> to filter by the test´s status in the last run
--filter-tags <tag-list> to filter by the tags of a test


Tags can be used for finegrained filtering of which tests to run via --filter-tags. This accepts a comma separated list of tags. Only tests that match all of these tags will be executed. For example, bats --filter-tags a,b,c will pick up tests with tags a,b,c, but not tests that miss one or more of those tags.

Additionally, you can specify negative tags via bats --filter-tags a,!b,c, which now won´t match tests with tags a,b,c, due to the b, but will select a,c. To put it more formally, --filter-tags is a boolean conjunction.

To allow for more complex queries, you can specify multiple --filter-tags. A test will be executed, if it matches at least one of them. This means multiple --filter-tags form a boolean disjunction.

A query of --filter-tags a,!b --filter-tags b,c can be translated to: Execute only tests that (have tag a, but not tag b) or (have tag b and c).

An empty tag list matches tests without tags.


Count the number of test cases without running any tests
A two character string of code quote delimiters or custom which requires setting $BATS_BEGIN_CODE_QUOTE and $BATS_END_CODE_QUOTE. Can also be set via $BATS_CODE_QUOTE_STYLE.
Filter test cases by names matching the regular expression
Switch between formatters: pretty (default), tap (default w/o term), tap13, junit, /<absolute path to formatter>
Only run tests with the given status in the last completed (no CTRL+C/SIGINT) run. Valid status values are: failed - runs tests that failed or were not present in the last run missed - runs tests that were not present in the last run
Only run tests that match all the tags in the list (&&). You can negate a tag via prepending !. Specifying this flag multiple times allows for logical or (||): --filter-tags A,B --filter-tags A,!C matches tags (A && B) || (A && !C)
Gather the output of failing and passing tests as files in directory
Display this help message
Number of parallel jobs (requires GNU parallel)
Preserve test output temporary directory
Serialize test file execution instead of running them in parallel (requires --jobs >1)
Serialize test execution within files instead of running them in parallel (requires --jobs >1)
Switch between reporters (same options as --formatter)
Directory to write report files
Shorthand for "--formatter pretty"
Automatically print the value of $output on failed tests
Include tests in subdirectories
Print output of passing tests
Shorthand for "--formatter tap"
Add timing information to tests
Print test commands as they are executed (like set -x)
Make run print $output by default
Display the version number


When you run Bats from a terminal, you´ll see output as each test is performed, with a check-mark next to the test´s name if it passes or an "X" if it fails.

$ bats addition.bats

✓ addition using bc
✓ addition using dc 2 tests, 0 failures

If Bats is not connected to a terminal--in other words, if you run it from a continuous integration system or redirect its output to a file--the results are displayed in human-readable, machine-parsable TAP format. You can force TAP output from a terminal by invoking Bats with the --tap option.

$ bats --tap addition.bats
ok 1 addition using bc
ok 2 addition using dc


The bats interpreter exits with a value of 0 if all test cases pass, or 1 if one or more test cases fail.


Bats wiki:

bash(1), bats(7)


(c) 2017-2022 bats-core organization
(c) 2011-2016 Sam Stephenson

Bats is released under the terms of an MIT-style license.

November 2022 bats-core