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fhtagn is a CLI tool for testing command-line programs.

If the test succeeds it exits silently with code 0. But if the test fails, fhtagn will output a diff between the expected output and the actual output.

fhtagn example gif


$ command to be run
| success output
@ expected error
? expected exit code


The script uses /usr/bin/awk which is not where awk is located on NixOS.

The workaround is a script that calls

awk -f fhtagn.awk

since that will find the PATH version of awk.