Code review

Author: Andy Hanson

src/harness/fourslash.ts

@@ -2435,6 +2435,7 @@ Actual: ${stringify(fullActual)}`);
             ts.Debug.assert(ts.contains(fixIds, fixId), "No available code fix has that group id.", () => `Expected '${fixId}'. Available action ids: ${fixIds}`);
             const { changes, commands } = this.languageService.getCombinedCodeFix({ type: "file", fileName: this.activeFile.fileName }, fixId, this.formatCodeSettings);
             assert.deepEqual(commands, options.commands);
+            assert(changes.every(c => c.fileName === this.activeFile.fileName), "TODO: support testing codefixes that touch multiple files");
             this.applyChanges(changes);
             this.verifyCurrentFileContent(newFileContent);
         }

src/server/client.ts

@@ -553,14 +553,14 @@ namespace ts.server {
             return notImplemented();
         }
 
-        getCodeFixesAtPosition(file: string, start: number, end: number, errorCodes: number[]): CodeFixAction[] {
+        getCodeFixesAtPosition(file: string, start: number, end: number, errorCodes: ReadonlyArray<number>): ReadonlyArray<CodeFixAction> {
             const args: protocol.CodeFixRequestArgs = { ...this.createFileRangeRequestArgs(file, start, end), errorCodes };
 
             const request = this.processRequest<protocol.CodeFixRequest>(CommandNames.GetCodeFixes, args);
             const response = this.processResponse<protocol.CodeFixResponse>(request);
 
             // TODO: GH#20538 shouldn't need cast
-            return (response.body as protocol.CodeFixAction[]).map(({ description, changes, fixId }) => ({ description, changes: this.convertChanges(changes, file), fixId }));
+            return (response.body as ReadonlyArray<protocol.CodeFixAction>).map(({ description, changes, fixId }) => ({ description, changes: this.convertChanges(changes, file), fixId }));
         }
 
         getCombinedCodeFix = notImplemented;

src/server/protocol.ts

@@ -619,7 +619,7 @@ namespace ts.server.protocol {
         /**
          * Errorcodes we want to get the fixes for.
          */
-        errorCodes?: number[];
+        errorCodes?: ReadonlyArray<number>;
     }
 
     // TODO: GH#20538

src/services/services.ts

@@ -1883,7 +1883,7 @@ namespace ts {
             return [];
         }
 
-        function getCodeFixesAtPosition(fileName: string, start: number, end: number, errorCodes: number[], formatOptions: FormatCodeSettings): CodeFixAction[] {
+        function getCodeFixesAtPosition(fileName: string, start: number, end: number, errorCodes: ReadonlyArray<number>, formatOptions: FormatCodeSettings): ReadonlyArray<CodeFixAction> {
             synchronizeHostData();
             const sourceFile = getValidSourceFile(fileName);
             const span = createTextSpanFromBounds(start, end);

src/services/types.ts

@@ -295,8 +295,8 @@ namespace ts {
 
         getSpanOfEnclosingComment(fileName: string, position: number, onlyMultiLine: boolean): TextSpan;
 
-        // TODO: GH#20538 return `CodeFixAction[]`
-        getCodeFixesAtPosition(fileName: string, start: number, end: number, errorCodes: number[], formatOptions: FormatCodeSettings): CodeAction[];
+        // TODO: GH#20538 return `ReadonlyArray<CodeFixAction>`
+        getCodeFixesAtPosition(fileName: string, start: number, end: number, errorCodes: ReadonlyArray<number>, formatOptions: FormatCodeSettings): ReadonlyArray<CodeAction>;
         // TODO: GH#20538
         /* @internal */
         getCombinedCodeFix(scope: CombinedCodeFixScope, fixId: {}, formatOptions: FormatCodeSettings): CombinedCodeActions;
@@ -428,8 +428,8 @@ namespace ts {
     // TODO: GH#20538
     /* @internal */
     export interface CombinedCodeActions {
-        changes: FileTextChanges[];
-        commands: CodeActionCommand[] | undefined;
+        changes: ReadonlyArray<FileTextChanges>;
+        commands: ReadonlyArray<CodeActionCommand> | undefined;
     }
 
     // Publicly, this type is just `{}`. Internally it is a union of all the actions we use.