Update test to verify files named 'COM1'

src/Workspaces/CoreTestUtilities/Resources/ProjectFiles/CSharp/MallformedAdditionalFilePath.csproj

@@ -42,6 +42,7 @@
   <ItemGroup>
     <AdditionalFiles Include="ValidAdditionalFile.txt" />
     <AdditionalFiles Include="TEST::" />
+    <AdditionalFiles Include="COM1" />
   </ItemGroup>
   <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />

src/Workspaces/MSBuildTest/MSBuildWorkspaceTests.cs

@@ -3598,6 +3598,7 @@ public async Task TestOpenProjectAsync_MalformedAdditionalFilePath()
                 // Project should open without an exception being thrown.
                 Assert.NotNull(project);
 
+                Assert.Contains(project.AdditionalDocuments, doc => doc.Name == "COM1");
                 Assert.Contains(project.AdditionalDocuments, doc => doc.Name == "TEST::");
             }
         }