test(dashboard): add auth guard tests for all 4 token×merchant states

src/__tests__/dashboard-layout.test.tsx

@@ -0,0 +1,135 @@
+/**
+ * Tests for /dashboard/layout.tsx auth guards
+ * Issue: all 4 combinations of token × merchant state
+ *   - token + merchant   → renders dashboard UI
+ *   - token only         → blank render (null), no redirect
+ *   - merchant only      → redirects to /auth/login (token missing)
+ *   - neither            → redirects to /auth/login
+ */
+import React from 'react';
+import { render, screen, act } from '@testing-library/react';
+import { useAuthStore } from '@/lib/store';
+import DashboardLayout from '@/app/dashboard/layout';
+
+// ─── Mocks ──────────────────────────────────────────────────────────────────
+
+const mockPush = jest.fn();
+
+jest.mock('next/navigation', () => ({
+  useRouter: () => ({ push: mockPush }),
+  usePathname: () => '/dashboard',
+}));
+
+jest.mock('next/link', () => ({
+  __esModule: true,
+  default: ({ children, href }: { children: React.ReactNode; href: string }) => (
+    <a href={href}>{children}</a>
+  ),
+}));
+
+// We control useAuthStore by mocking the whole store module
+jest.mock('@/lib/store');
+
+const mockUseAuthStore = useAuthStore as jest.MockedFunction<typeof useAuthStore>;
+
+// ─── Helpers ─────────────────────────────────────────────────────────────────
+
+const MOCK_MERCHANT = {
+  id: 'merchant-1',
+  email: 'test@example.com',
+  businessName: 'Acme Corp',
+  status: 'active',
+};
+
+function stubAuth(overrides: { token?: string | null; merchant?: typeof MOCK_MERCHANT | null }) {
+  const state = {
+    token: overrides.token ?? null,
+    merchant: overrides.merchant ?? null,
+    logout: jest.fn(),
+    setAuth: jest.fn(),
+  };
+  // useAuthStore is called with a selector fn: useAuthStore(state => state.foo)
+  mockUseAuthStore.mockImplementation((selector?: (s: typeof state) => unknown) => {
+    if (selector) return selector(state) as ReturnType<typeof useAuthStore>;
+    return state as unknown as ReturnType<typeof useAuthStore>;
+  });
+}
+
+// ─── Tests ───────────────────────────────────────────────────────────────────
+
+beforeEach(() => {
+  jest.clearAllMocks();
+  jest.useFakeTimers();
+});
+
+afterEach(() => {
+  jest.runOnlyPendingTimers();
+  jest.useRealTimers();
+});
+
+describe('DashboardLayout — auth guards', () => {
+  it('[token + merchant] renders the dashboard shell and children', async () => {
+    stubAuth({ token: 'valid-token', merchant: MOCK_MERCHANT });
+
+    render(
+      <DashboardLayout>
+        <div data-testid="child-content">Dashboard Content</div>
+      </DashboardLayout>,
+    );
+
+    // Children should be visible
+    expect(screen.getByTestId('child-content')).toBeInTheDocument();
+    // Merchant business name should appear in sidebar
+    expect(screen.getByText('Acme Corp')).toBeInTheDocument();
+    // Should NOT redirect
+    await act(async () => { jest.runAllTimers(); });
+    expect(mockPush).not.toHaveBeenCalled();
+  });
+
+  it('[token only, no merchant] returns null (blank render) — no redirect', async () => {
+    stubAuth({ token: 'valid-token', merchant: null });
+
+    const { container } = render(
+      <DashboardLayout>
+        <div data-testid="child-content">Dashboard Content</div>
+      </DashboardLayout>,
+    );
+
+    // The layout returns null when merchant is missing
+    expect(container.firstChild).toBeNull();
+    // Children should NOT be rendered
+    expect(screen.queryByTestId('child-content')).not.toBeInTheDocument();
+    // Should NOT redirect (token is present)
+    await act(async () => { jest.runAllTimers(); });
+    expect(mockPush).not.toHaveBeenCalled();
+  });
+
+  it('[no token, merchant present] redirects to /auth/login', async () => {
+    stubAuth({ token: null, merchant: MOCK_MERCHANT });
+
+    render(
+      <DashboardLayout>
+        <div data-testid="child-content">Dashboard Content</div>
+      </DashboardLayout>,
+    );
+
+    // The redirect is triggered in a useEffect — flush it
+    await act(async () => { jest.runAllTimers(); });
+
+    expect(mockPush).toHaveBeenCalledWith('/auth/login');
+  });
+
+  it('[no token, no merchant] redirects to /auth/login', async () => {
+    stubAuth({ token: null, merchant: null });
+
+    render(
+      <DashboardLayout>
+        <div data-testid="child-content">Dashboard Content</div>
+      </DashboardLayout>,
+    );
+
+    await act(async () => { jest.runAllTimers(); });
+
+    expect(mockPush).toHaveBeenCalledWith('/auth/login');
+  });
+});