SC2314

bats: ! <command> will never fail the test

Problematic code:

#!/usr/bin/env bats

@test "test" {
    # ... code
    ! test_file_exists
    # ... more code
}

Correct code:

#!/usr/bin/env bats

@test "test" {
    # ... code
    run ! test_file_exists
    # ... more code
}

Rationale:

Bats uses set -e and trap ERR to catch test failures as early as possible. Although the return code of a ! negated command is inverted, they will never trigger errexit, due to a bash design decision (see Related Resources). This means that tests which use ! can never fail.

Starting with bats 1.5.0 you can use ! inside run. If you are still using an older bats version, you can rewrite ! <command> to <command> && exit 1.

Exceptions:

The return code of the last command in the test will be the exit code of the test function. This means that you can use ! <command> on the last line of the test and it will still fail appropriately. However, you are encouraged to still use run ! in this case for consistency.

Shellcheck won't emit this error when using ! <command> as last command in a test to avoid confusing users whose tests work as intended.

Related resources:

• SC2251: This ! is not on a condition and skips errexit
• Stackoverflow: Why do I need parenthesis In bash set -e and negated return code
• bash manpage (look at trap [-lp] [[arg] sigspec ...]):

  The ERR trap is not executed [...] if the command's return value is being inverted via !