bats 1.13.0 (The man files)

Bats is a TAP-compliant (http://testanything.org/) testing
framework for Bash.
It provides a simple and repeatable 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.

Bats is most useful when testing software written in Bash, but you can use it
to test any UNIX program.

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