feat(lmxproxy): phase 4 — host health monitoring, metrics, status web server

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lmxproxy/tests/ZB.MOM.WW.LmxProxy.Host.Tests/Metrics/PerformanceMetricsTests.cs

@@ -0,0 +1,147 @@
+using System;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Xunit;
+using ZB.MOM.WW.LmxProxy.Host.Metrics;
+
+namespace ZB.MOM.WW.LmxProxy.Host.Tests.Metrics
+{
+    public class PerformanceMetricsTests
+    {
+        [Fact]
+        public void RecordOperation_TracksCountAndDuration()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            for (int i = 0; i < 5; i++)
+            {
+                metrics.RecordOperation("TestOp", TimeSpan.FromMilliseconds(10), true);
+            }
+
+            var stats = metrics.GetStatistics();
+            stats.Should().ContainKey("TestOp");
+            stats["TestOp"].TotalCount.Should().Be(5);
+        }
+
+        [Fact]
+        public void RecordOperation_TracksSuccessAndFailure()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            for (int i = 0; i < 3; i++)
+            {
+                metrics.RecordOperation("TestOp", TimeSpan.FromMilliseconds(10), true);
+            }
+            for (int i = 0; i < 2; i++)
+            {
+                metrics.RecordOperation("TestOp", TimeSpan.FromMilliseconds(10), false);
+            }
+
+            var stats = metrics.GetStatistics();
+            stats["TestOp"].SuccessRate.Should().BeApproximately(0.6, 0.001);
+        }
+
+        [Fact]
+        public void GetStatistics_CalculatesP95Correctly()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            for (int i = 1; i <= 100; i++)
+            {
+                metrics.RecordOperation("TestOp", TimeSpan.FromMilliseconds(i), true);
+            }
+
+            var stats = metrics.GetStatistics();
+            stats["TestOp"].Percentile95Milliseconds.Should().BeApproximately(95.0, 1.0);
+        }
+
+        [Fact]
+        public void RollingBuffer_CapsAt1000Samples()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            for (int i = 0; i < 1500; i++)
+            {
+                metrics.RecordOperation("TestOp", TimeSpan.FromMilliseconds(i), true);
+            }
+
+            var stats = metrics.GetStatistics();
+            // TotalCount tracks all 1500 but percentile is computed from the last 1000
+            stats["TestOp"].TotalCount.Should().Be(1500);
+            // The rolling buffer should have entries from 500-1499
+            // P95 of 500..1499 should be around 1449
+            stats["TestOp"].Percentile95Milliseconds.Should().BeGreaterThan(1000);
+        }
+
+        [Fact]
+        public void BeginOperation_RecordsDurationOnDispose()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            using (var scope = metrics.BeginOperation("TestOp"))
+            {
+                System.Threading.Thread.Sleep(50);
+            }
+
+            var stats = metrics.GetStatistics();
+            stats.Should().ContainKey("TestOp");
+            stats["TestOp"].TotalCount.Should().Be(1);
+            stats["TestOp"].AverageMilliseconds.Should().BeGreaterOrEqualTo(40);
+        }
+
+        [Fact]
+        public void TimingScope_DefaultsToSuccess()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            using (metrics.BeginOperation("TestOp"))
+            {
+                // Do nothing — default is success
+            }
+
+            var stats = metrics.GetStatistics();
+            stats["TestOp"].SuccessCount.Should().Be(1);
+        }
+
+        [Fact]
+        public void TimingScope_RespectsSetSuccessFalse()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            using (var scope = metrics.BeginOperation("TestOp"))
+            {
+                scope.SetSuccess(false);
+            }
+
+            var stats = metrics.GetStatistics();
+            stats["TestOp"].SuccessCount.Should().Be(0);
+            stats["TestOp"].TotalCount.Should().Be(1);
+        }
+
+        [Fact]
+        public void GetMetrics_ReturnsNullForUnknownOperation()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            var result = metrics.GetMetrics("DoesNotExist");
+
+            result.Should().BeNull();
+        }
+
+        [Fact]
+        public void GetAllMetrics_ReturnsAllTrackedOperations()
+        {
+            using var metrics = new PerformanceMetrics();
+
+            metrics.RecordOperation("Read", TimeSpan.FromMilliseconds(10), true);
+            metrics.RecordOperation("Write", TimeSpan.FromMilliseconds(20), true);
+            metrics.RecordOperation("Subscribe", TimeSpan.FromMilliseconds(5), true);
+
+            var all = metrics.GetAllMetrics();
+            all.Should().ContainKey("Read");
+            all.Should().ContainKey("Write");
+            all.Should().ContainKey("Subscribe");
+            all.Count.Should().Be(3);
+        }
+    }
+}