Corrects Span ID format for adding to Log Entries.

Fixes googleapis#5358.

apis/Google.Cloud.Diagnostics.AspNetCore/Google.Cloud.Diagnostics.AspNetCore.Tests/Logging/TraceContextForLogEntryTests.cs

@@ -0,0 +1,95 @@
+// Copyright 2020 Google LLC
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     https://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using Google.Cloud.Diagnostics.Common;
+using Moq;
+using Xunit;
+
+namespace Google.Cloud.Diagnostics.AspNetCore.Tests
+{
+    public class TraceContextForLogEntryTests
+    {
+        [Fact]
+        public void FromGoogleTrace()
+        {
+            var oldTracer = ContextTracerManager.GetCurrentTracer();
+            try
+            {
+                string traceId = "dummy_trace_id";
+                ulong spanId = 0x12D687;
+                // The spanId set on the log entry should confirm to x16
+                // format so that the backend can really associate the log entry
+                // to the span.
+                string expectedSpanId = "000000000012d687";
+
+                ContextTracerManager.SetCurrentTracer(MockTracer(traceId, spanId));
+
+                var traceContext = TraceContextForLogEntry.FromGoogleTrace();
+
+                Assert.Equal(traceId, traceContext.TraceId);
+                Assert.Equal(expectedSpanId, traceContext.SpanId);
+            }
+            finally
+            {
+                ContextTracerManager.SetCurrentTracer(oldTracer);
+            }            
+        }
+
+        [Fact]
+        public void FromGoogleTrace_NoTrace()
+        {
+            var oldTracer = ContextTracerManager.GetCurrentTracer();
+            try
+            {
+                ContextTracerManager.SetCurrentTracer(MockTracer());
+
+                Assert.Null(TraceContextForLogEntry.FromGoogleTrace());
+            }
+            finally
+            {
+                ContextTracerManager.SetCurrentTracer(oldTracer);
+            }
+        }
+
+        [Fact]
+        public void FromGoogleTrace_NoSpan()
+        {
+            var oldTracer = ContextTracerManager.GetCurrentTracer();
+            try
+            {
+                string traceId = "dummy_trace_id";
+
+                ContextTracerManager.SetCurrentTracer(MockTracer(traceId));
+
+                var traceContext = TraceContextForLogEntry.FromGoogleTrace();
+
+                Assert.Equal(traceId, traceContext.TraceId);
+                Assert.Null(traceContext.SpanId);
+            }
+            finally
+            {
+                ContextTracerManager.SetCurrentTracer(oldTracer);
+            }
+        }
+
+        private IManagedTracer MockTracer(string traceId = null, ulong? spanId = null)
+        {
+            Mock<IManagedTracer> tracerMock = new Mock<IManagedTracer>(MockBehavior.Strict);
+            tracerMock.Setup(t => t.GetCurrentTraceId()).Returns(traceId);
+            tracerMock.Setup(t => t.GetCurrentSpanId()).Returns(spanId);
+
+            return tracerMock.Object;
+        }
+    }
+}

apis/Google.Cloud.Diagnostics.AspNetCore/Google.Cloud.Diagnostics.AspNetCore/Logging/TraceContextForLogEntry.cs

@@ -62,7 +62,6 @@ internal static TraceContextForLogEntry FromGoogleTrace() =>
         internal static TraceContextForLogEntry FromExternalTrace(IServiceProvider serviceProvider) =>
             serviceProvider?.GetService<IExternalTraceProvider>()?.GetCurrentTraceContext(serviceProvider);
 
-        private static string SpanIdToHex(ulong? spanId) => spanId is null ? null : string.Format("0x{0:X}", spanId);
-
+        private static string SpanIdToHex(ulong? spanId) => spanId is null ? null : $"{spanId:x16}";
     }
 }

apis/Google.Cloud.Diagnostics.Common/Google.Cloud.Diagnostics.Common.IntegrationTests/EntryData.cs

@@ -28,6 +28,6 @@ public static class EntryData
         /// </summary>
         public static string GetMessage(string message, string id) => $"{message} - {id}";
 
-        public static string SpanIdToHex(ulong? spanId) => spanId is null ? null : string.Format("0x{0:X}", spanId);
+        public static string SpanIdToHex(ulong? spanId) => spanId is null ? null : $"{spanId:x16}";
     }
 }