NAME

Test::Metrics::Any - assert that code produces metrics via Metrics::Any

SYNOPSIS

   use Test::More;
   use Test::Metrics::Any;

   use Module::Under::Test;

   is_metrics_from(
      sub { Module::Under::Test::do_a_thing for 1 .. 5 },
      {
         things_done => 5,
         time_taken => Test::Metrics::Any::positive,
      },
      'do_a_thing reported some metrics'
   );

   done_testing;

DESCRIPTION

This test module helps write unit tests which assert that the code under test reports metrics via Metrics::Any.

Loading this module automatically sets the Metrics::Any::Adapter type to Test.

FUNCTIONS

is_metrics

   is_metrics( \%metrics, $name )

Asserts that the current value of every metric named in the given hash reference is set to the value provided. Values can either be given as exact numbers, or by one of the match functions mentioned in "PREDICATES".

Key names in the given hash should match the name format used by Metrics::Any::Adapter::Test. Name components are joined by underscores, and any label tags are appended with spaces, as name:value.

   {
      "a_basic_metric"               => 123,
      "a_labelled_metric label:here" => 456,
   }

This function only checks the values of metrics actually mentioned in the hash given as its argument. It is not a failure for more metrics to have been reported by the code under test than are mentioned in the hash. This helps to ensure that new metrics added in code do not break existing tests that weren't set up to expect them.

is_metrics_from

   is_metrics_from( $code, \%metrics, $name )

Asserts the value of metrics reported by running the given piece of code.

The metrics in the test adapter are cleared, then the code is invoked, then any metrics are checked in the same manner as "is_metrics".

PREDICATES

As an alternative to expecting exact values for metrics, the following test functions can be provided instead to assert that the metric is behaving sensibly without needing to be an exact value. This could be useful for example when the exact number of bytes or timing measures can vary between test runs or platforms.

These predicates are not exported but must be invoked fully-qualified.

positive

   metric => Test::Metrics::Any::positive

Asserts that the number is greater than zero. It must not be zero.

at_least

   metric => Test::Metrics::Any::at_least( $n )

Asserts that the number at least that given - it can be equal or greater.

greater_than

   metric => Test::Metrics::Any::greater_than( $n )

Asserts that the number is greater than that given - it must not be equal.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>