Add tests

Author: IcySteam

.bazelrc

@@ -17,9 +17,9 @@ build --copt -DGRPC_BAZEL_BUILD
 build:windows --dynamic_mode=off
 
 # Set minimum supported C++ version
-build:macos --host_cxxopt=-std=c++17 --cxxopt=-std=c++17
-build:linux --host_cxxopt=-std=c++17 --cxxopt=-std=c++17
-build:windows --host_cxxopt=/std:c++17 --cxxopt=/std:c++17
+build:macos --host_cxxopt=-std=c++14 --cxxopt=-std=c++14
+build:linux --host_cxxopt=-std=c++14 --cxxopt=-std=c++14
+build:windows --host_cxxopt=/std:c++14 --cxxopt=/std:c++14
 
 # --config=asan : Address Sanitizer.
 common:asan --copt -DADDRESS_SANITIZER

sdk/include/opentelemetry/sdk/metrics/meter_context.h

@@ -98,17 +98,20 @@ class MeterContext : public std::enable_shared_from_this<MeterContext>
   opentelemetry::common::SystemTimestamp GetSDKStartTime() noexcept;
 
   /**
-   * Attaches a metric reader to list of configured readers for this Meter context.
-   * @param reader The metric reader for this meter context. This
-   * must not be a nullptr.
-   * @param metric_filter The optional metric filter for the metric producer on which the supplied
-   * metric reader is to be registered.
+   * Create a MetricCollector from a MetricReader using this MeterContext and add it to the list of
+   * configured collectors.
+   * @param reader The MetricReader for which a MetricCollector is to be created. This must not be a
+   * nullptr.
+   * @param metric_filter The optional MetricFilter used when creating the MetricCollector.
+   * @return The MetricCollector created.
    *
    * Note: This reader may not receive any in-flight meter data, but will get newly created meter
-   * data. Note: This method is not thread safe, and should ideally be called from main thread.
+   * data.
+   * Note: This method is not thread safe, and should ideally be called from main thread.
    */
-  void AddMetricReader(std::shared_ptr<MetricReader> reader,
-                       absl::optional<MetricFilter> metric_filter = absl::nullopt) noexcept;
+  std::shared_ptr<MetricCollector> AddMetricReader(
+      std::shared_ptr<MetricReader> reader,
+      absl::optional<MetricFilter> metric_filter = absl::nullopt) noexcept;
 
   /**
    * Attaches a View to list of configured Views for this Meter context.

sdk/include/opentelemetry/sdk/metrics/meter_provider.h

@@ -81,17 +81,20 @@ class OPENTELEMETRY_EXPORT MeterProvider final : public opentelemetry::metrics::
   const sdk::resource::Resource &GetResource() const noexcept;
 
   /**
-   * Attaches a metric reader to list of configured readers for this Meter providers.
-   * @param reader The metric reader for this meter provider. This
-   * must not be a nullptr.
-   * @param metric_filter The optional metric filter for the metric producer on which the supplied
-   * metric reader is to be registered.
+   * Create a MetricCollector from a MetricReader using the MeterContext of this MeterProvider and
+   * add it to the list of configured collectors.
+   * @param reader The MetricReader for which a MetricCollector is to be created. This must not be a
+   * nullptr.
+   * @param metric_filter The optional MetricFilter used when creating the MetricCollector.
+   * @return The MetricCollector created.
    *
    * Note: This reader may not receive any in-flight meter data, but will get newly created meter
-   * data. Note: This method is not thread safe, and should ideally be called from main thread.
+   * data.
+   * Note: This method is not thread safe, and should ideally be called from main thread.
    */
-  void AddMetricReader(std::shared_ptr<MetricReader> reader,
-                       absl::optional<MetricFilter> metric_filter = absl::nullopt) noexcept;
+  std::shared_ptr<MetricCollector> AddMetricReader(
+      std::shared_ptr<MetricReader> reader,
+      absl::optional<MetricFilter> metric_filter = absl::nullopt) noexcept;
 
   /**
    * Attaches a View to list of configured Views for this Meter provider.

sdk/src/metrics/meter_context.cc

@@ -80,12 +80,14 @@ opentelemetry::common::SystemTimestamp MeterContext::GetSDKStartTime() noexcept
   return sdk_start_ts_;
 }
 
-void MeterContext::AddMetricReader(std::shared_ptr<MetricReader> reader,
-                                   absl::optional<MetricFilter> metric_filter) noexcept
+std::shared_ptr<MetricCollector> MeterContext::AddMetricReader(
+    std::shared_ptr<MetricReader> reader,
+    absl::optional<MetricFilter> metric_filter) noexcept
 {
   auto collector =
       std::shared_ptr<MetricCollector>{new MetricCollector(this, std::move(reader), metric_filter)};
   collectors_.push_back(collector);
+  return collector;
 }
 
 void MeterContext::AddView(std::unique_ptr<InstrumentSelector> instrument_selector,

sdk/src/metrics/meter_provider.cc

@@ -110,10 +110,11 @@ const resource::Resource &MeterProvider::GetResource() const noexcept
   return context_->GetResource();
 }
 
-void MeterProvider::AddMetricReader(std::shared_ptr<MetricReader> reader,
-                                    absl::optional<MetricFilter> metric_filter) noexcept
+std::shared_ptr<MetricCollector> MeterProvider::AddMetricReader(
+    std::shared_ptr<MetricReader> reader,
+    absl::optional<MetricFilter> metric_filter) noexcept
 {
-  context_->AddMetricReader(std::move(reader), metric_filter);
+  return context_->AddMetricReader(std::move(reader), metric_filter);
 }
 
 void MeterProvider::AddView(std::unique_ptr<InstrumentSelector> instrument_selector,

sdk/test/metrics/BUILD

@@ -27,6 +27,7 @@ cc_test(
     ],
     deps = [
         "metrics_common_test_utils",
+        "//exporters/ostream:ostream_metric_exporter",
         "@com_google_googletest//:gtest_main",
     ],
 )

sdk/test/metrics/CMakeLists.txt

@@ -27,6 +27,7 @@ foreach(
   observer_result_test
   sync_instruments_test
   async_instruments_test
+  metric_collector_test
   metric_reader_test
   observable_registry_test
   periodic_exporting_metric_reader_test