Add tests for prompt input model whitespace

Author: Tyriar

src/vs/platform/terminal/test/common/capabilities/commandDetection/promptInputModel.test.ts

@@ -491,6 +491,57 @@ suite('PromptInputModel', () => {
 	});
 
 	suite('trailing whitespace', () => {
+		test('cursor index calculation with whitespace', async () => {
+			await writePromise('$ ');
+			fireCommandStart();
+			await assertPromptInput('|');
+
+			await writePromise('echo   ');
+			await assertPromptInput('echo   |');
+
+			await writePromise('\x1b[3D');
+			await assertPromptInput('echo|   ');
+
+			await writePromise('\x1b[C');
+			await assertPromptInput('echo |  ');
+
+			await writePromise('\x1b[C');
+			await assertPromptInput('echo  | ');
+
+			await writePromise('\x1b[C');
+			await assertPromptInput('echo   |');
+		});
+
+		test('cursor index should not exceed command line length', async () => {
+			await writePromise('$ ');
+			fireCommandStart();
+			await assertPromptInput('|');
+
+			await writePromise('cmd');
+			await assertPromptInput('cmd|');
+
+			await writePromise('\x1b[10C');
+			await assertPromptInput('cmd|');
+		});
+
+		test('whitespace preservation in cursor calculation', async () => {
+			await writePromise('$ ');
+			fireCommandStart();
+			await assertPromptInput('|');
+
+			await writePromise('ls   -la');
+			await assertPromptInput('ls   -la|');
+
+			await writePromise('\x1b[3D');
+			await assertPromptInput('ls   |-la');
+
+			await writePromise('\x1b[3D');
+			await assertPromptInput('ls|   -la');
+
+			await writePromise('\x1b[2C');
+			await assertPromptInput('ls  | -la');
+		});
+
 		test('delete whitespace with backspace', async () => {
 			await writePromise('$ ');
 			fireCommandStart();