Add debugging messages around execution to see if we can figure out w…

…here the duplicate IDs are coming from

src/xunit.runner.visualstudio/VsTestRunner.cs

@@ -508,6 +508,8 @@ async Task RunTestsInAssembly(
 				var testCaseSerializations = new List<string>();
 				if (runInfo.TestCases is null || !runInfo.TestCases.Any())
 				{
+					logger.LogWithSource(assemblyFileName, "Discovering tests for full assembly execution");
+
 					// Discover tests
 					var assemblyDiscoveredInfo = default(AssemblyDiscoveredInfo);
 					await DiscoverTestsInAssembly(
@@ -554,13 +556,19 @@ await DiscoverTestsInAssembly(
 							testCaseSerializations.Add(filteredTestCase.TestCase.Serialization);
 						}
 					}
+
+					logger.LogWithSource(assemblyFileName, "Discovery complete");
 				}
 				else
 				{
+					logger.LogWithSource(assemblyFileName, "Selective execution requested for the following test case serializations:");
+
 					foreach (var testCase in runInfo.TestCases)
 					{
 						var uniqueID = testCase.GetPropertyValue<string>(TestCaseUniqueIDProperty, null);
 						var serialization = testCase.GetPropertyValue<string>(TestCaseSerializationProperty, null);
+						logger.LogWithSource(assemblyFileName, "  {0} :: {1}", uniqueID ?? "(null)", serialization ?? "(null)");
+
 						if (uniqueID is null)
 							logger.LogWarningWithSource(assemblyFileName, "VSTestCase {0} did not have an associated unique ID", testCase.DisplayName);
 						else if (testCasesMap.ContainsKey(uniqueID))