Add an initial test

dotnet · tarekgh · Jul 18, 2024 · Jun 26, 2024 · Jul 1, 2024 · Jul 3, 2024
commit 1ca6ff91ae983e5ec50d7f82a8029403361a8ed9
diff --git a/src/libraries/System.Diagnostics.DiagnosticSource/tests/RuntimeMetricsTests.cs b/src/libraries/System.Diagnostics.DiagnosticSource/tests/RuntimeMetricsTests.cs
@@ -0,0 +1,102 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace System.Diagnostics.Metrics.Tests
+{
+    public class RuntimeMetricsTests
+    {
+        [Fact]
+        public async Task GcCollectionsCount()
+        {
+            using InstrumentRecorder<long> instrumentRecorder = new("dotnet.gc.collections.count");
+            using CancellationTokenSource cts = new(1000);
+
+            for (var gen = 0; gen <= GC.MaxGeneration; gen++)
+            {
+                GC.Collect(gen, GCCollectionMode.Forced);
+            }
+
+            instrumentRecorder.RecordObservableInstruments();
+
+            (bool success, IReadOnlyList<Measurement<long>> measurements) = await WaitForMeasurements(instrumentRecorder, 3, cts.Token);
+
+            Assert.True(success, "Expected to receive at least 3 measurements.");
+
+            int count = 0;
+            for (int i = GC.MaxGeneration; i >= 0; i--)
+            {
+                Measurement<long> measurement = measurements[count++];
+                Assert.True(measurement.Value > 0, $"Gen {i} count should be greater than zero.");
+
+                var tags = measurement.Tags.ToArray();
+
+                Assert.Equal(1, tags.Length);
+                VerifyTag(tags, "gc.heap.generation", $"gen{i}");
+            }
+        }
+
+        private static async Task<(bool, IReadOnlyList<Measurement<T>>)> WaitForMeasurements<T>(InstrumentRecorder<T> instrumentRecorder,
+            int expected, CancellationToken cancellationToken) where T : struct
+        {
+            IReadOnlyList<Measurement<T>> measurements;
+            while ((measurements = instrumentRecorder.GetMeasurements()).Count < 3)
+            {
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return (false, measurements);
+                }
+
+                await Task.Delay(50, cancellationToken);
+            }
+
+            return (true, measurements);
+        }
+
+        private static void VerifyTag<T>(KeyValuePair<string, object?>[] tags, string name, T value)
+        {
+            if (value is null)
+            {
+                Assert.DoesNotContain(tags, t => t.Key == name);
+            }
+            else
+            {
+                Assert.Equal(value, (T)tags.Single(t => t.Key == name).Value);
+            }
+        }
+
+        protected sealed class InstrumentRecorder<T> : IDisposable where T : struct
+        {
+            private readonly MeterListener _meterListener = new();
+            private readonly ConcurrentQueue<Measurement<T>> _values = new();
+
+            public InstrumentRecorder(string instrumentName)
+            {
+                _meterListener.InstrumentPublished = (instrument, listener) =>
+                {
+                    if (instrument.Meter.Name == "System.Runtime" && instrument.Name == instrumentName)
+                    {
+                        listener.EnableMeasurementEvents(instrument);
+                    }
+                };
+                _meterListener.SetMeasurementEventCallback<T>(OnMeasurementRecorded);
+                _meterListener.Start();
+            }
+
+            private void OnMeasurementRecorded(Instrument instrument, T measurement, ReadOnlySpan<KeyValuePair<string, object?>> tags, object? state) =>
+                _values.Enqueue(new Measurement<T>(measurement, tags));
+
+            public IReadOnlyList<Measurement<T>> GetMeasurements() => _values.ToArray();
+
+            public void RecordObservableInstruments() => _meterListener.RecordObservableInstruments();
+
+            public void Dispose() => _meterListener.Dispose();
+        }
+    }
+}
diff --git a/...ystem.Diagnostics.DiagnosticSource/tests/System.Diagnostics.DiagnosticSource.Tests.csproj b/...ystem.Diagnostics.DiagnosticSource/tests/System.Diagnostics.DiagnosticSource.Tests.csproj
@@ -35,6 +35,7 @@
     <Compile Include="MetricsAdviceTests.cs" />
     <Compile Include="MetricsTests.cs" />
     <Compile Include="PropagatorTests.cs" />
+    <Compile Include="RuntimeMetricsTests.cs" />
     <Compile Include="TagListTests.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'">