NAME

       "Metrics::Any::Adapter::Test" - a metrics reporting adapter for unit testing

SYNOPSIS

          use Test2::V0;
          use Metrics::Any::Adapter 'Test';

          {
             Metrics::Any::Adapter::Test->clear;

             # perform some work in the code under test

             is( Metrics::Any::Adapter::Test->metrics,
                "an_expected_metric = 1\n",
                'Metrics were reported while doing something'
             );
          }

DESCRIPTION

       This Metrics::Any adapter type stores reported metrics locally, allowing access to them by
       the "metrics" method. This is useful to use in a unit test to check that the code under
       test reports the correct metrics.

       This adapter supports timer metrics by storing as distributions. By default, distributions
       store only a summary, giving the count and total duration. If required, the full values
       can be stored by setting "use_full_distributions".

       For predictable output of timer metrics in unit tests, a unit test may wish to use the
       "override_timer_duration" method.

       This adapter type supports batch mode reporting. Callbacks are invoked at the beginning of
       the "metrics" method.

METHODS

   metrics
          $result = Metrics::Any::Adapter::Test->metrics

       This class method returns a string describing all of the stored metric values.  Each is
       reported on a line formatted as

          name = value

       Each line, including the final one, is terminated by a linefeed. The metrics are sorted
       alphabetically. Any multi-part metric names will be joined with underscores ("_").

       Metrics that have additional labels are formatted with additional label names and label
       values in declared order after the name and before the "=" symbol:

          name l1:v1 l2:v2 = value

   use_full_distributions
          Metrics::Any::Adapter::Test->use_full_distributions;  # enables the option

          Metrics::Any::Adapter::Test->use_full_distributions( $enable );

       Since version 0.08.

       If enabled, this option stores the full value of every reported observation into
       distributions, rathr than just the count-and-total summary.

       Full value distributions will be formatted as a sequence of lines containing the count of
       observations at that particular value, in square brackets, followed by the summary count.

          name[v1] = c1
          name[v2] = c2
          ...
          name_count = c

       In order not to be too sensitive to numerical rounding errors, values are stored to only 3
       decimal places.

   clear
          Metrics::Any::Adapter::Test->clear

       This class method removes all of the stored values of reported metrics.

   override_timer_duration
          Metrics::Any::Adapter::Test->override_timer_duration( $duration )

       This class method sets a duration value, that any subsequent call to "inc_timer" will use
       instead of the value the caller actually passed in. This will ensure reliably predictable
       output in unit tests.

       Any value set here will be cleared by "clear".

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>