Add/modify asserts

src/EditorFeatures/CSharpTest/Workspaces/WorkspaceTests.cs

@@ -907,7 +907,7 @@ public async Task TestAdditionalFile_OpenClose()
 
                 // Make sure that additional documents are included in GetOpenDocumentIds.
                 var openDocumentIds = workspace.GetOpenDocumentIds();
-                Assert.Equal(1, openDocumentIds.Count());
+                Assert.Single(openDocumentIds);
                 Assert.Equal(additionalDoc.Id, openDocumentIds.Single());
 
                 workspace.OnAdditionalDocumentClosed(additionalDoc.Id, TextLoader.From(TextAndVersion.Create(text, version)));
@@ -1002,11 +1002,11 @@ public void TestAdditionalFile_GetDocumentIdsWithFilePath()
                 workspace.AddTestProject(project1);
 
                 var documentIdsWithFilePath = workspace.CurrentSolution.GetDocumentIdsWithFilePath(docFilePath);
-                Assert.Equal(1, documentIdsWithFilePath.Count());
+                Assert.Single(documentIdsWithFilePath);
                 Assert.Equal(document.Id, documentIdsWithFilePath.Single());
 
                 documentIdsWithFilePath = workspace.CurrentSolution.GetDocumentIdsWithFilePath(additionalDocFilePath);
-                Assert.Equal(1, documentIdsWithFilePath.Count());
+                Assert.Single(documentIdsWithFilePath);
                 Assert.Equal(additionalDoc.Id, documentIdsWithFilePath.Single());
             }
         }

src/Workspaces/Core/Portable/Workspace/Workspace_Editor.cs

@@ -3,6 +3,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -627,7 +628,8 @@ private SourceText GetOpenDocumentText(Solution solution, DocumentId documentId)
             CheckDocumentIsOpen(documentId);
             var doc = solution.GetDocument(documentId);
             // text should always be preserved, so TryGetText will succeed.
-            doc.TryGetText(out var text);
+            var success = doc.TryGetText(out var text);
+            Debug.Assert(success);
             return text;
         }
 
@@ -636,7 +638,8 @@ private SourceText GetOpenAdditionalDocumentText(Solution solution, DocumentId d
             CheckDocumentIsOpen(documentId);
             var doc = solution.GetAdditionalDocument(documentId);
             // text should always be preserved, so TryGetText will succeed.
-            doc.TryGetText(out var text);
+            var success = doc.TryGetText(out var text);
+            Debug.Assert(success);
             return text;
         }