fix(cli): gemini command stuck in git bash (#6397)

Co-authored-by: Arya Gummadi <aryagummadi@google.com>

packages/cli/src/utils/readStdin.test.ts

@@ -0,0 +1,112 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { vi, describe, expect, it, beforeEach, afterEach } from 'vitest';
+import { readStdin } from './readStdin.js';
+
+// Mock process.stdin
+const mockStdin = {
+  setEncoding: vi.fn(),
+  read: vi.fn(),
+  on: vi.fn(),
+  removeListener: vi.fn(),
+  destroy: vi.fn(),
+};
+
+describe('readStdin', () => {
+  let originalStdin: typeof process.stdin;
+  let onReadableHandler: () => void;
+  let onEndHandler: () => void;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    originalStdin = process.stdin;
+
+    // Replace process.stdin with our mock
+    Object.defineProperty(process, 'stdin', {
+      value: mockStdin,
+      writable: true,
+      configurable: true,
+    });
+
+    // Capture event handlers
+    mockStdin.on.mockImplementation((event: string, handler: () => void) => {
+      if (event === 'readable') onReadableHandler = handler;
+      if (event === 'end') onEndHandler = handler;
+    });
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    Object.defineProperty(process, 'stdin', {
+      value: originalStdin,
+      writable: true,
+      configurable: true,
+    });
+  });
+
+  it('should read and accumulate data from stdin', async () => {
+    mockStdin.read
+      .mockReturnValueOnce('I love ')
+      .mockReturnValueOnce('Gemini!')
+      .mockReturnValueOnce(null);
+
+    const promise = readStdin();
+
+    // Trigger readable event
+    onReadableHandler();
+
+    // Trigger end to resolve
+    onEndHandler();
+
+    await expect(promise).resolves.toBe('I love Gemini!');
+  });
+
+  it('should handle empty stdin input', async () => {
+    mockStdin.read.mockReturnValue(null);
+
+    const promise = readStdin();
+
+    // Trigger end immediately
+    onEndHandler();
+
+    await expect(promise).resolves.toBe('');
+  });
+
+  // Emulate terminals where stdin is not TTY (eg: git bash)
+  it('should timeout and resolve with empty string when no input is available', async () => {
+    vi.useFakeTimers();
+
+    const promise = readStdin();
+
+    // Fast-forward past the timeout (to run test faster)
+    vi.advanceTimersByTime(500);
+
+    await expect(promise).resolves.toBe('');
+
+    vi.useRealTimers();
+  });
+
+  it('should clear timeout once when data is received and resolve with data', async () => {
+    const clearTimeoutSpy = vi.spyOn(global, 'clearTimeout');
+    mockStdin.read
+      .mockReturnValueOnce('chunk1')
+      .mockReturnValueOnce('chunk2')
+      .mockReturnValueOnce(null);
+
+    const promise = readStdin();
+
+    // Trigger readable event
+    onReadableHandler();
+
+    expect(clearTimeoutSpy).toHaveBeenCalledOnce();
+
+    // Trigger end to resolve
+    onEndHandler();
+
+    await expect(promise).resolves.toBe('chunk1chunk2');
+  });
+});