bats - Man Page

Bash Automated Testing System

Examples (TL;DR)

Synopsis

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")

Description

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.

Running 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.

Filtering Tests

There are multiple mechanisms to filter which tests to execute:

--FILTER-TAGS <var>TAG-LIST</var>

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.

Options

Output

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
 āœ“ addition using bc
 āœ“ 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
1..2
ok 1 addition using bc
ok 2 addition using dc

Exit Status

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

See Also

Bats wiki: https://github.com/bats-core/bats-core/wiki/

bash(1), bats(7)

Referenced By

bats(7).

July 2026 bats-core Bash Automated Testing System