Fixed issue when EventFlowLogger throws on duplicate log message arguments (#413)

* fixed issue when EventFlowLogger throws on duplicate log message arguments

* PR feedback

Author: n-sidorov

src/Microsoft.Diagnostics.EventFlow.Inputs.MicrosoftLogging/Logger/EventFlowLogger.cs

@@ -40,7 +40,7 @@ public void Log<TState>(Extensions.Logging.LogLevel logLevel, EventId eventId, T
 
             Dictionary<string, object> properties = new Dictionary<string, object>();
 
-            ApplyOmittingUnformattedMessage(state, item => properties.Add(item.Key, item.Value));
+            ApplyOmittingUnformattedMessage(state, item => properties[item.Key] = item.Value);
 
             var scope = EventFlowLoggerScope.Current;
             if (scope != null)

src/Microsoft.Diagnostics.EventFlow.Inputs.MicrosoftLogging/Microsoft.Diagnostics.EventFlow.Inputs.MicrosoftLogging.csproj

@@ -6,7 +6,7 @@
     <Authors>Microsoft</Authors>
     <TargetFrameworks>netstandard1.6;netstandard2.0;net462</TargetFrameworks>
     <AssemblyName>Microsoft.Diagnostics.EventFlow.Inputs.MicrosoftLogging</AssemblyName>
-    <VersionPrefix>1.6.0</VersionPrefix>
+    <VersionPrefix>1.6.1</VersionPrefix>
     <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
     <PackageId>Microsoft.Diagnostics.EventFlow.Inputs.MicrosoftLogging</PackageId>
     <PackageTags>Microsoft;Diagnostics;EventFlow;Inputs;MicrosoftLogging</PackageTags>

test/Microsoft.Diagnostics.EventFlow.Inputs.Tests/LoggerInputTests.cs

@@ -49,6 +49,40 @@ public void LoggerShouldSubmitData()
             }
         }
 
+        [Fact]
+        public void LoggerShouldSubmitDataWhenEncounterDuplicates()
+        {
+            var healthReporterMock = new Mock<IHealthReporter>();
+            var subject = new Mock<IObserver<EventData>>();
+            EventData savedData = null;
+            subject.Setup(s => s.OnNext(It.IsAny<EventData>())).Callback((EventData data) => savedData = data);
+
+            using (LoggerInput target = new LoggerInput(healthReporterMock.Object))
+            {
+                var diagnosticPipeline = createPipeline(target, healthReporterMock.Object);
+                using (target.Subscribe(subject.Object))
+                {
+                    var factory = new LoggerFactory();
+                    factory.AddEventFlow(diagnosticPipeline);
+                    var logger = new Logger<LoggerInputTests>(factory);
+                    logger.LogInformation("log message {number} {number}", 1, 1);
+                    subject.Verify(s => s.OnNext(It.Is<EventData>(data => checkEventData(
+                        data,
+                        "log message 1 1",
+                        typeof(LoggerInputTests).FullName,
+                        LogLevel.Informational,
+                        0,
+                        null,
+                        new Dictionary<string, object> { { "number", 1 } }))), Times.Exactly(1));
+
+                    assertDoesNotContainDuplicate(savedData.Payload, keyPrefix: "number", expectedValue: 1);
+
+                    healthReporterMock.Verify(it => it.ReportWarning(It.IsAny<string>(), It.IsAny<string>()), Times.Never());
+                    healthReporterMock.Verify(it => it.ReportProblem(It.IsAny<string>(), It.IsAny<string>()), Times.Never());
+                }
+            }
+        }
+
         [Fact]
         public void LoggerShouldSubmitException()
         {
@@ -516,6 +550,13 @@ private void assertContainsDuplicate(IDictionary<string, object> payload, string
             Assert.Equal(expectedValue, payload[duplicates.First()]);
         }
 
+        private void assertDoesNotContainDuplicate(IDictionary<string, object> payload, string keyPrefix, object expectedValue)
+        {
+            var singleValue = payload.Keys.Where(k => k.StartsWith(keyPrefix)).ToArray();
+            Assert.Single(singleValue);
+            Assert.Equal(expectedValue, payload[singleValue.First()]);
+        }
+
         private DiagnosticPipeline createPipeline(LoggerInput input, IHealthReporter reporter)
         {
             return new DiagnosticPipeline(reporter, new[] { input }, null, new[] { new EventSink(new FakeOutput(), null) });