TAP (Test Anything Protocol) is a simple text format for describing test results. Some example TAP output might look 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
   
TAP allows you to :
* (optionally) describe the number of tests you expect to run (the test plan)
* (optionally) describe the order you expect to run them
* describe which tests passed or failed
* describe tests that are not run (skipped tests) 
* describe whether the test was expected to fail (TODO tests)
* output diagnostic messages that explain test failure
For details see Test::Harness::TAP (http://search.cpan.org/dist/Test-Harness/lib/Test/Harness/TAP.pod)

TAP is at the core of the majority of the PerlLanguage testing modules living under the Test:: hierarchy on TheCpan (http://search.cpan.org/search?query=Test%3A%3A%3A&mode=dist). See http://qa.perl.org/test-modules.html for a brief summary of some of them, and http://qa.perl.org for more general information on PerlLanguage testing.

The core modules that support TAP in the PerlLanguage are:

* Test::Harness (http://search.cpan.org/dist/Test-Harness/) 
** Runs test scripts, parses their TAP output and summarises test results. Includes a command line test runner ''prove''

* Test::Builder (http://search.cpan.org/dist/Test-Builder/)
** Base module used to write PerlLanguage testing modules that output TAP

* Test::Simple (http://search.cpan.org/dist/Test-Simple/)
** The minimum you need to start writing TAP tests. Allows you to specify a test plan and whether tests pass or fail.

* Test::More (http://search.cpan.org/dist/Test-Simple/lib/Test/More.pm)
** Extends Test::Simple with a bunch of useful assertions.

While TAP is most commonly used with the PerlLanguage, it's simple enough that you can hack together a basic TAP library with very little effort. TAP libraries exist for PhpLanguage (http://shiflett.org/archive/176), JavaScript (http://www.openjsan.org/doc/t/th/theory/Test/Simple/) and many other languages.

Since TAP tries to be methodology agnostic, you can integrate different testing modules with different testing styles together under a single test harness (e.g., both the xUnit-ish PerlTestClass and the specification-based LectroTest output TAP).

Since TAP is just ASCII it is easy to throw around with pipes, SSH, etc., so you can throw together cross-platform, multi-language, multi-server test farms using your standard Unix toolset.

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CategoryPerl, CategoryTesting