bash-it/vendor/github.com/rcaloras/bash-preexec/test/README.md

Testing bash-preexec

Note on test conditions

When writing test conditions, use [ ... ] instead of [[ ... ]] since the former are supported by Bats on Bash versions before 4.1. In particular, macOS uses Bash 3.2, and [[ ... ]] tests always pass on macOS.

In some cases, you may want to use a feature unique to [[ ... ]] such as pattern matching ([[ $name = a* ]]) or regular expressions ([[ $(date) =~ ^Fri\ ...\ 13 ]]). In those cases, use the following pattern to replace “bare” [[ ... ]].

[[ ... ]] || return 1

References:

• Differences between [ and [[
• Problems with [[ in Bats
• Using || return 1 instead of || false