test: Add tests for MeterProvider API (#1441)

* test: Add tests for MeterProvider API

- Make `name` a required argument
- Add test for `MeterProvider#meter`
- Add test for `OpenTelemetry.{meter_provider,meter_provider=}`

* Number parameters (that _1 syntax) is not available in Ruby 2.6

Ruby 2.6 is the mininum version we support

* Fix mock error regarding keyword args

* Use version as a keyword warg in meter method

* Fix linter issue

metrics_api/lib/opentelemetry/internal/proxy_meter_provider.rb

@@ -37,7 +37,7 @@ def delegate=(provider)
 
         @mutex.synchronize do
           @delegate = provider
-          @registry.each { |key, meter| meter.delegate = provider.meter(key.name, key.version) }
+          @registry.each { |key, meter| meter.delegate = provider.meter(key.name, version: key.version) }
         end
       end
 
@@ -47,9 +47,9 @@ def delegate=(provider)
       # @param [optional String] version Instrumentation package version
       #
       # @return [Meter]
-      def meter(name = nil, version = nil)
+      def meter(name = nil, version: nil)
         @mutex.synchronize do
-          return @delegate.meter(name, version) unless @delegate.nil?
+          return @delegate.meter(name, version: version) unless @delegate.nil?
 
           @registry[Key.new(name, version)] ||= ProxyMeter.new
         end

metrics_api/lib/opentelemetry/metrics/meter_provider.rb

@@ -10,11 +10,11 @@ module Metrics
     class MeterProvider
       # Returns a {Meter} instance.
       #
-      # @param [optional String] name Instrumentation package name
+      # @param [String] name Instrumentation package name
       # @param [optional String] version Instrumentation package version
       #
       # @return [Meter]
-      def meter(name = nil, version = nil)
+      def meter(name, version: nil)
         @meter ||= Meter.new
       end
     end

metrics_api/test/opentelemetry/metrics/meter_provider_test.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+# Copyright The OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'test_helper'
+
+describe OpenTelemetry::Metrics::MeterProvider do
+  describe '#meter' do
+    it 'requires a name' do
+      meter_provider = build_meter_provider
+
+      _(-> { meter_provider.meter }).must_raise(ArgumentError)
+    end
+
+    it 'returns an instance of Meter' do
+      meter_provider = build_meter_provider
+
+      assert(meter_provider.meter('test', version: '1.0.0').is_a?(OpenTelemetry::Metrics::Meter))
+    end
+  end
+
+  def build_meter_provider
+    OpenTelemetry::Metrics::MeterProvider.new
+  end
+end

metrics_api/test/opentelemetry/opentelemetry_test.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+# Copyright The OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'test_helper'
+
+describe OpenTelemetry do
+  after do
+    # TODO: After Metrics SDK is incoporated into OpenTelemetry SDK, move this
+    # to OpenTelemetry::TestHelpers.reset_opentelemetry
+    OpenTelemetry.instance_variable_set(
+      :@meter_provider,
+      OpenTelemetry::Internal::ProxyMeterProvider.new
+    )
+  end
+
+  describe '#meter_provider and #meter_provider=' do
+    it 'initializes with a global instance of ProxyMeterProvider' do
+      assert(OpenTelemetry.meter_provider.is_a?(OpenTelemetry::Internal::ProxyMeterProvider))
+    end
+
+    it 'sets global MeterProvider to the given meter_provider' do
+      new_meter_provider = OpenTelemetry::Metrics::MeterProvider.new
+
+      OpenTelemetry.meter_provider = new_meter_provider
+
+      assert(OpenTelemetry.meter_provider.object_id == new_meter_provider.object_id)
+    end
+
+    describe 'when global MeterProvider is an instance of Internal::ProxyMeterProvider' do
+      it 'sets ProxyMeterProvider#delegate to the given meter_provider and logs a debug message' do
+        proxy_meter_provider = OpenTelemetry.meter_provider
+        new_meter_provider = OpenTelemetry::Metrics::MeterProvider.new
+
+        OpenTelemetry::TestHelpers.with_test_logger do |log_stream|
+          OpenTelemetry.meter_provider = new_meter_provider
+
+          assert(proxy_meter_provider.instance_variable_get(:@delegate).object_id == new_meter_provider.object_id)
+          assert(OpenTelemetry.meter_provider.object_id == new_meter_provider.object_id)
+          assert(log_stream.string.match?(/Upgrading default proxy meter provider to #{new_meter_provider.class}/i))
+        end
+      end
+    end
+  end
+end

metrics_sdk/lib/opentelemetry/sdk/metrics/aggregation/explicit_bucket_histogram.rb

@@ -79,7 +79,7 @@ def update(amount, attributes)
             hdp.sum += amount
             hdp.count += 1
             if @boundaries
-              bucket_index = @boundaries.bsearch_index { _1 >= amount } || @boundaries.size
+              bucket_index = @boundaries.bsearch_index { |i| i >= amount } || @boundaries.size
               hdp.bucket_counts[bucket_index] += 1
             end
             nil

metrics_sdk/lib/opentelemetry/sdk/metrics/meter_provider.rb

@@ -30,7 +30,7 @@ def initialize(resource: OpenTelemetry::SDK::Resources::Resource.create)
         # @param [optional String] version Instrumentation package version
         #
         # @return [Meter]
-        def meter(name, version = nil)
+        def meter(name, version: nil)
           version ||= ''
           if @stopped
             OpenTelemetry.logger.warn 'calling MeterProvider#meter after shutdown, a noop meter will be returned.'

metrics_sdk/test/opentelemetry/sdk/metrics/meter_provider_test.rb

@@ -60,8 +60,8 @@
     it 'invokes shutdown on all registered Metric Readers' do
       mock_metric_reader1 = new_mock_reader
       mock_metric_reader2 = new_mock_reader
-      mock_metric_reader1.expect(:shutdown, nil, [{ timeout: nil }])
-      mock_metric_reader2.expect(:shutdown, nil, [{ timeout: nil }])
+      mock_metric_reader1.expect(:shutdown, nil, [], timeout: nil)
+      mock_metric_reader2.expect(:shutdown, nil, [], timeout: nil)
 
       OpenTelemetry.meter_provider.add_metric_reader(mock_metric_reader1)
       OpenTelemetry.meter_provider.add_metric_reader(mock_metric_reader2)
@@ -84,8 +84,8 @@
     it 'invokes force_flush on all registered Metric Readers' do
       mock_metric_reader1 = new_mock_reader
       mock_metric_reader2 = new_mock_reader
-      mock_metric_reader1.expect(:force_flush, nil, [{ timeout: nil }])
-      mock_metric_reader2.expect(:force_flush, nil, [{ timeout: nil }])
+      mock_metric_reader1.expect(:force_flush, nil, [], timeout: nil)
+      mock_metric_reader2.expect(:force_flush, nil, [], timeout: nil)
       OpenTelemetry.meter_provider.add_metric_reader(mock_metric_reader1)
       OpenTelemetry.meter_provider.add_metric_reader(mock_metric_reader2)