Accepting a member completion should result in valid code

Fixes #58597

Default to replacing the word range in js/ts. This is a change in core behavior so  we'll need to see what the feedback is like for it.

extensions/typescript-language-features/src/features/completions.ts

@@ -125,11 +125,17 @@ class MyCompletionItem extends vscode.CompletionItem {
 
 		// Try getting longer, prefix based range for completions that span words
 		const wordRange = this.document.getWordRangeAtPosition(this.position);
+		if (wordRange) {
+			this.range = wordRange;
+		}
+
 		const text = line.slice(Math.max(0, this.position.character - this.label.length), this.position.character).toLowerCase();
 		const entryName = this.label.toLowerCase();
 		for (let i = entryName.length; i >= 0; --i) {
 			if (text.endsWith(entryName.substr(0, i)) && (!wordRange || wordRange.start.character > this.position.character - i)) {
-				this.range = new vscode.Range(this.position.line, Math.max(0, this.position.character - i), this.position.line, this.position.character);
+				this.range = new vscode.Range(
+					new vscode.Position(this.position.line, Math.max(0, this.position.character - i)),
+					this.position);
 				break;
 			}
 		}

extensions/typescript-language-features/src/test/completions.test.ts

@@ -162,6 +162,20 @@ suite('TypeScript Completions', () => {
 			));
 	});
 
+	test('Accepting a member completion should result in valid code. #58597', async () => {
+		await createTestEditor(testDocumentUri,
+			`const abc = 123;`,
+			`ab$0c`
+		);
+
+		const document = await acceptFirstSuggestion(testDocumentUri, _disposables);
+		assert.strictEqual(
+			document.getText(),
+			joinLines(
+				`const abc = 123;`,
+				`abc`
+			));
+	});
 });
 
 const joinLines = (...args: string[]) => args.join('\n');