Populate required field Message with n/a if it is empty (#2857)

* Populate required field Message with n/a if it is empty

* Move using Microsoft.Application.Insights.DataContracts to be within namespace

* Address PR comments by fixing test to use message, and using a utility method to check for null/whitespace

BASE/Test/Microsoft.ApplicationInsights.Test/Microsoft.ApplicationInsights.Tests/Extensibility/Implementation/ExceptionConverterTest.cs

@@ -185,6 +185,19 @@ public void DoesNotTrimShortExceptionMessages()
             Assert.AreEqual(5, expDetails.message.Length);
         }
 
+        [TestMethod]
+        [DataRow(null)]
+        [DataRow("")]
+        [DataRow(" ")]
+        public void ProvidesDefaultMessage(string message)
+        {
+            var exp = new ExceptionWithMessageOverride(message);
+
+            ExceptionDetails expDetails = ExceptionConverter.ConvertToExceptionDetails(exp, null);
+
+            Assert.AreEqual("n/a", expDetails.message);
+        }
+
         [MethodImplAttribute(MethodImplOptions.NoInlining)]
         private Exception CreateException(int numberOfStackpoints)
         {
@@ -212,5 +225,20 @@ private void FailedFunction(int numberOfStackpoints)
 
             throw new AggregateException("exception message");
         }
+
+        /// <summary>
+        /// Overrides the Message property of the base exception, so that null messages are
+        /// returned as null, rather than a default, e.g. "Exception of type 'System.Exception' was thrown".
+        /// </summary>
+        private class ExceptionWithMessageOverride : Exception
+        {
+            public ExceptionWithMessageOverride(string message)
+                : base(message)
+            {
+                Message = message;
+            }
+
+            public override string Message { get; }
+        }
     }
 }

BASE/src/Microsoft.ApplicationInsights/Extensibility/Implementation/External/ExceptionDetailsImplementation.cs

@@ -1,6 +1,7 @@
 namespace Microsoft.ApplicationInsights.Extensibility.Implementation.External
 {
     using System;
+    using Microsoft.ApplicationInsights.DataContracts;
 
     /// <summary>
     /// Additional implementation for ExceptionDetails.
@@ -21,7 +22,7 @@ internal static ExceptionDetails CreateWithoutStackInfo(Exception exception, Exc
             {
                 id = exception.GetHashCode(),
                 typeName = exception.GetType().FullName,
-                message = exception.Message,
+                message = Utils.PopulateRequiredNonWhitespaceStringValue(exception.Message, "message", typeof(ExceptionTelemetry).FullName),
             };
 
             if (parentExceptionDetails != null)

BASE/src/Microsoft.ApplicationInsights/Extensibility/Implementation/Utils.cs

@@ -52,6 +52,20 @@ public static string PopulateRequiredStringValue(string value, string parameterN
             return value;
         }
 
+        /// <summary>
+        /// Validates the string and if null or empty populates it with '$parameterName is a required field for $telemetryType' value.
+        /// </summary>
+        public static string PopulateRequiredNonWhitespaceStringValue(string value, string parameterName, string telemetryType)
+        {
+            if (value.IsNullOrWhiteSpace())
+            {
+                CoreEventSource.Log.PopulateRequiredStringWithValue(parameterName, telemetryType);
+                return "n/a";
+            }
+
+            return value;
+        }
+
         /// <summary>
         /// Returns default Timespan value if not a valid Timespan.
         /// </summary>

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## VNext
+- [Populate required field Message with "n/a" if it is empty](https://github.com/microsoft/ApplicationInsights-dotnet/issues/1066)
 
 ## Version 2.22.0
 - no changes since beta.