NAME

       Test2::Manual::Tooling::Testing - Tutorial on how to test your testing tools.

DESCRIPTION

       Testing your test tools used to be a complex and difficult prospect. The old tools such as
       Test::Tester and Test::Builder::Tester were limited, and fragile. Test2 on the other hand
       was designed from the very start to be easily tested! This tutorial shows you how.

THE HOLY GRAIL OF TESTING YOUR TOOLS

       The key to making Test2 easily testable (specially when compared to Test::Builder) is the
       "intercept" function.

           use Test2::API qw/intercept/;

           my $events = intercept {
               ok(1, "pass");
               ok(0, "fail");

               diag("A diag");
           };

       The intercept function lets you use any test tools you want inside a codeblock.  No events
       or contexts generated within the intercept codeblock will have any effect on the outside
       testing state. The "intercept" function completely isolates the tools called within.

       Note: Plugins and things that effect global API state may not be fully isolated.
       "intercept" is intended specifically for event isolation.

       The "intercept" function will return an arrayref containing all the events that were
       generated within the codeblock. You can now make any assertions you want about the events
       you expected your tools to generate.

           [
               bless({...}, 'Test2::Event::Ok'),   # pass
               bless({...}, 'Test2::Event::Ok'),   # fail
               bless({...}, 'Test2::Event::Diag'), # Failure diagnostics (not always a second event)
               bless({...}, 'Test2::Event::Diag'), # custom 'A diag' message
           ]

       Most test tools eventually produce one or more events. To effectively verify the events
       you get from intercept you really should read up on how events work
       Test2::Manual::Anatomy::Event. Once you know about events you can move on to the next
       section which points you at some helpers.

ADDITIONAL HELPERS

   Test2::Tools::Tester
       This is the most recent set of tools to help you test your events. To really understand
       these you should familiarize yourself with Test2::Manual::Anatomy::Event. If you are going
       to be writing anything more than the most simple of tools you should know how events work.

       The Test2::Tools::Tester documentation is a good place for further reading.

   Test2::Tools::HarnessTester
       The Test2::Tools::HarnessTester can export the "summarize_events()" tool.  This tool lets
       you run your event arrayref through Test2::Harness so that you can get a pass/fail
       summary.

           my $summary = summarize_events($events);

       The summary looks like this:

           {
               plan       => $plan_facet,         # the plan event facet
               pass       => $bool,               # true if the events result in a pass
               fail       => $bool,               # true if the events result in a fail
               errors     => $error_count,        # Number of error facets seen
               failures   => $failure_count,      # Number of failing assertions seen
               assertions => $assertion_count,    # Total number of assertions seen
           }

   Test2::Tools::Compare
       DEPRECATED These tools were written before the switch to faceted events.  These will still
       work, but are no longer the recommended way to test your tools.

       The Test2::Tools::Compare library exports a handful of extras to help test events.

       event $TYPE => ...
           Use in an array check against $events to check for a specific type of event with the
           properties you specify.

       fail_events $TYPE => ...
           Use when you expect a failing assertion of $TYPE. This will automatically check that
           the next event following it is a diagnostics message with the default failure text.

           Note: This is outdated as a single event may now possess both the failing assertion
           AND the failing text, such events will fail this test.

SEE ALSO

       Test2::Manual - Primary index of the manual.

SOURCE

       The source code repository for Test2-Manual can be found at
       https://github.com/Test-More/Test2-Suite/.

MAINTAINERS

       Chad Granum <exodist@cpan.org>

AUTHORS

       Chad Granum <exodist@cpan.org>

COPYRIGHT

       Copyright 2017 Chad Granum <exodist@cpan.org>.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       See http://dev.perl.org/licenses/