The following tests come from Brian Kernighan's tests collection:

- data/ contains sample data used as input
- examples/ contains example AWK programs
    - p.* files are examples from The Awk Programming Environment (TAPE)
    - t.* files are Kernighan's collection of useful examples
- re/ contains tests for regular expressions
- sub/ contains substitution tests
- benchmarks/ contains benchmark programs

The tests in gnu/ and syn/ were gathered tests from gawk's "basic" and
"unix-tests" targets (SHA 682b4299a9fd3023211e9db09f8e258d0ffd07e6).
Tests for the following were removed, since they aren't relevant to nawk:

- Tested gawk's --lint behaviour
- Differences between passing --traditional and not passing it
- GNU-specific functions (like gensub, asort, asorti, and strftime)
- GNU-specific builtins (like PROCINFO)
- GNU-specific special variables (IGNORECASE)
- Features that nawk doesn't support yet (like setting RS to a regex)