metrics_test_helpers.rb

# frozen_string_literal: true

# Copyright The OpenTelemetry Authors
#
# SPDX-License-Identifier: Apache-2.0

require 'minitest/spec'

module OpenTelemetry
  module MetricsTestHelpers
    module LoadedMetricsFeatures
      OTEL_METRICS_API_LOADED = !Gem.loaded_specs['opentelemetry-metrics-api'].nil?
      OTEL_METRICS_SDK_LOADED = !Gem.loaded_specs['opentelemetry-metrics-sdk'].nil?

      extend self

      def api_loaded?
        OTEL_METRICS_API_LOADED
      end

      def sdk_loaded?
        OTEL_METRICS_SDK_LOADED
      end
    end

    module MinitestExtensions
      def self.prepended(base)
        base.extend(self)
      end

      def self.included(base)
        base.extend(self)
      end

      def before_setup
        super
        reset_metrics_exporter
      end

      def with_metrics_sdk
        yield if LoadedMetricsFeatures.sdk_loaded?
      end

      def without_metrics_sdk
        yield unless LoadedMetricsFeatures.sdk_loaded?
      end

      def metrics_exporter
        with_metrics_sdk { METRICS_EXPORTER }
      end

      def reset_meter_provider
        with_metrics_sdk do
          resource = OpenTelemetry.meter_provider.resource
          OpenTelemetry.meter_provider = OpenTelemetry::SDK::Metrics::MeterProvider.new(resource: resource)
          OpenTelemetry.meter_provider.add_metric_reader(METRICS_EXPORTER)
        end
      end

      def reset_metrics_exporter
        with_metrics_sdk do
          METRICS_EXPORTER.pull
          METRICS_EXPORTER.reset
        end
      end

      def it(desc = 'anonymous', with_metrics_sdk: false, without_metrics_sdk: false, &block)
        return super(desc, &block) unless with_metrics_sdk || without_metrics_sdk

        raise ArgumentError, 'without_metrics_sdk and with_metrics_sdk must be mutually exclusive' if without_metrics_sdk && with_metrics_sdk

        return if with_metrics_sdk && !LoadedMetricsFeatures.sdk_loaded?
        return if without_metrics_sdk && LoadedMetricsFeatures.sdk_loaded?

        super(desc, &block)
      end
    end

    if LoadedMetricsFeatures.sdk_loaded?
      METRICS_EXPORTER = OpenTelemetry::SDK::Metrics::Export::InMemoryMetricPullExporter.new
      OpenTelemetry.meter_provider.add_metric_reader(METRICS_EXPORTER)
    end

    Minitest::Spec.prepend(MinitestExtensions)
  end
end