TAP, the Test Anything Protocol, is a simple text-based interface between testing modules in a test harness. It decouples the reporting of errors from the presentation of the reports.
One of its major uses is for noise reduction; when you have a suite of many tests, making them TAP producers and using a TAP consumer to view them helps ensures that you will see everything you need to notice and diagnose breakage without being distracted by a flood of irrelevant success messages. It can assist other forms of analysis and statistics-gathering as well.
Here’s what a TAP test stream looks like:
1..4 ok 1 - Input file opened not ok 2 - First line of the input valid ok 3 - Read the rest of the file not ok 4 - Summarized correctly # TODO Not written yet