Exclude unchangeable document from change namespace results

src/EditorFeatures/CSharpTest/CodeActions/SyncNamespace/CSharpSyncNamespaceTestsBase.cs

@@ -169,7 +169,6 @@ protected async Task TestMoveFileToMatchNamespace(string initialMarkup, List<str
                     var changedDocumentIds = SolutionUtilities.GetChangedDocuments(oldSolution, newSolution);
 
                     Assert.True(changedDocumentIds.Contains(originalDocumentId), "original document was not changed.");
-                    Assert.True(expectedSourceReference == null || changedDocumentIds.Contains(refDocumentId), "reference document was not changed.");
 
                     var modifiedOriginalDocument = newSolution.GetDocument(originalDocumentId);
                     var modifiedOringinalRoot = await modifiedOriginalDocument.GetSyntaxRootAsync();
@@ -195,8 +194,19 @@ protected async Task TestMoveFileToMatchNamespace(string initialMarkup, List<str
                     var actualText = (await modifiedOriginalDocument.GetTextAsync()).ToString();
                     Assert.Equal(expectedSourceOriginal, actualText);
 
-                    if (expectedSourceReference != null)
+                    if (expectedSourceReference == null)
                     {
+                        // there shouldn't be any textual change
+                        if (changedDocumentIds.Contains(refDocumentId))
+                        {
+                            var oldRefText = (await oldSolution.GetDocument(refDocumentId).GetTextAsync()).ToString();
+                            var newRefText = (await newSolution.GetDocument(refDocumentId).GetTextAsync()).ToString();
+                            Assert.Equal(oldRefText, newRefText);
+                        }
+                    }
+                    else
+                    {
+                        Assert.True(changedDocumentIds.Contains(refDocumentId));
                         var actualRefText = (await newSolution.GetDocument(refDocumentId).GetTextAsync()).ToString();
                         Assert.Equal(expectedSourceReference, actualRefText);
                     }

src/EditorFeatures/CSharpTest/CodeActions/SyncNamespace/SyncNamespaceTests_ChangeNamespace.cs

@@ -466,6 +466,62 @@ void M1()
             await TestChangeNamespaceAsync(code, expectedSourceOriginal, expectedSourceReference);
         }
 
+        [WorkItem(963225, "https://dev.azure.com/devdiv/DevDiv/_workitems/edit/963225")]
+        [WpfFact, Trait(Traits.Feature, Traits.Features.CodeActionsSyncNamespace)]
+        public async Task ChangeNamespace_WithReferencesInUnchangeableDocument()
+        {
+            var defaultNamespace = "A";
+            var declaredNamespace = "Foo.Bar.Baz";
+
+            var documentPath1 = CreateDocumentFilePath(new[] { "B", "C" }, "File1.cs");
+            var documentPath2 = CreateDocumentFilePath(Array.Empty<string>(), "File2.cs");
+            var code =
+$@"
+<Workspace>
+    <Project Language=""C#"" AssemblyName=""Assembly1"" FilePath=""{ProjectFilePath}"" RootNamespace=""{defaultNamespace}"" CommonReferences=""true"">
+        <Document Folders=""{documentPath1.folder}"" FilePath=""{documentPath1.filePath}""> 
+namespace [||]{declaredNamespace}
+{{
+    class Class1 
+    {{ 
+    }}
+    
+    class Class2 
+    {{ 
+    }}
+}}</Document>
+<Document Folders=""{documentPath2.folder}"" FilePath=""{documentPath2.filePath}"" CanApplyChange=""false""> 
+using Foo.Bar.Baz;
+
+namespace Foo
+{{
+    class RefClass
+    {{
+        private Class1 c1;
+
+        void M1()
+        {{
+            Bar.Baz.Class2 c2 = null;
+        }}
+    }}
+}}</Document>
+    </Project>
+</Workspace>";
+
+            var expectedSourceOriginal =
+@"namespace A.B.C
+{
+    class Class1
+    {
+    }
+
+    class Class2
+    {
+    }
+}";
+            await TestChangeNamespaceAsync(code, expectedSourceOriginal);
+        }
+
         [WpfFact, Trait(Traits.Feature, Traits.Features.CodeActionsSyncNamespace)]
         public async Task ChangeNamespace_WithQualifiedReferencesInOtherDocument()
         {

src/Features/Core/Portable/CodeRefactorings/SyncNamespace/AbstractChangeNamespaceService.cs

@@ -188,7 +188,9 @@ await ChangeNamespaceInSingleDocumentAsync(solutionAfterNamespaceChange, documen
                     ImmutableArray.Create(declaredNamespace, targetNamespace),
                     cancellationToken).ConfigureAwait(false);
 
-                return await MergeDiffAsync(solutionAfterFirstMerge, solutionAfterImportsRemoved, cancellationToken).ConfigureAwait(false);
+                var mergedSolution = await MergeDiffAsync(solutionAfterFirstMerge, solutionAfterImportsRemoved, cancellationToken).ConfigureAwait(false);
+
+                return await mergedSolution.ExcludeDisallowedDocumentTextChangesAsync(solution, cancellationToken).ConfigureAwait(false);
             }
             finally
             {