feat: added unit testing for frontend components using vitest

frontend/package.json

@@ -7,7 +7,8 @@
     "dev": "vite",
     "build": "tsc -b && vite build",
     "lint": "eslint .",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test": "vitest"
   },
   "dependencies": {
     "@hookform/resolvers": "^3.10.0",
@@ -67,6 +68,8 @@
   "devDependencies": {
     "@eslint/js": "^9.36.0",
     "@tailwindcss/postcss": "^4.1.14",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.0",
     "@types/node": "^24.6.0",
     "@types/react": "^19.1.16",
     "@types/react-dom": "^19.1.9",
@@ -76,9 +79,11 @@
     "eslint-plugin-react-hooks": "^5.2.0",
     "eslint-plugin-react-refresh": "^0.4.22",
     "globals": "^16.4.0",
+    "jsdom": "^27.0.1",
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.45.0",
-    "vite": "npm:[email protected]"
+    "vite": "npm:[email protected]",
+    "vitest": "^4.0.4"
   },
   "overrides": {
     "vite": "npm:[email protected]"

frontend/src/__tests__/Browse.test.tsx

@@ -0,0 +1,114 @@
+import { render, screen, fireEvent } from "@testing-library/react";
+import { describe, it, expect, vi } from "vitest";
+import { MemoryRouter } from "react-router-dom";
+import Browse from "../pages/Browse";
+
+describe("Browse Component", () => {
+  beforeEach(() => {
+    vi.spyOn(window, "alert").mockImplementation(() => {}); // prevent alert popups
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("renders the heading and product cards", () => {
+    render(
+      <MemoryRouter>
+        <Browse />
+      </MemoryRouter>
+    );
+
+    // Header
+    expect(screen.getByText(/Browse Products/i)).toBeInTheDocument();
+    expect(
+      screen.getByText(/Find what you need from fellow students/i)
+    ).toBeInTheDocument();
+
+    // Product cards visible
+    expect(screen.getByText("Desk Lamp")).toBeInTheDocument();
+    expect(screen.getByText("C++ Programming Book")).toBeInTheDocument();
+  });
+
+  it("filters products by search query", () => {
+    render(
+      <MemoryRouter>
+        <Browse />
+      </MemoryRouter>
+    );
+
+    const searchInput = screen.getByPlaceholderText(
+      /Search for textbooks, electronics, notes/i
+    );
+
+    // Type "lamp" in search bar
+    fireEvent.change(searchInput, { target: { value: "lamp" } });
+
+    // Only Desk Lamp should show
+    expect(screen.getByText("Desk Lamp")).toBeInTheDocument();
+    expect(screen.queryByText("Laptop Stand")).not.toBeInTheDocument();
+  });
+
+  it("opens and applies filter drawer", () => {
+    render(
+      <MemoryRouter>
+        <Browse />
+      </MemoryRouter>
+    );
+
+    // Click Filter button
+    const filterButton = screen.getByRole("button", { name: /Filter/i });
+    fireEvent.click(filterButton);
+
+    // Select Electronics category
+    const categorySelect = screen.getByLabelText(/Category/i);
+    fireEvent.change(categorySelect, { target: { value: "electronics" } });
+
+    // Apply filters
+    const applyBtn = screen.getByRole("button", { name: /Apply Filters/i });
+    fireEvent.click(applyBtn);
+
+    expect(window.alert).toHaveBeenCalledWith(
+      expect.stringContaining("Category: electronics")
+    );
+  });
+
+  it("clears filters when clicking 'Clear'", () => {
+    render(
+      <MemoryRouter>
+        <Browse />
+      </MemoryRouter>
+    );
+
+    const filterButton = screen.getByRole("button", { name: /Filter/i });
+    fireEvent.click(filterButton);
+
+    // Change category to "notes"
+    const categorySelect = screen.getByLabelText(/Category/i);
+    fireEvent.change(categorySelect, { target: { value: "notes" } });
+
+    // Click Clear
+    const clearButton = screen.getByRole("button", { name: /Clear/i });
+    fireEvent.click(clearButton);
+
+    expect(categorySelect).toHaveValue("");
+  });
+
+  it("triggers alert when 'Add to Cart' is clicked", () => {
+    render(
+      <MemoryRouter>
+        <Browse />
+      </MemoryRouter>
+    );
+
+    const addToCartButton = screen.getAllByRole("button", {
+      name: /Add to Cart/i,
+    })[0];
+
+    fireEvent.click(addToCartButton);
+
+    expect(window.alert).toHaveBeenCalledWith(
+      expect.stringContaining("added to cart")
+    );
+  });
+});

frontend/src/__tests__/Navbar.test.tsx

@@ -0,0 +1,58 @@
+import { render, screen, fireEvent } from "@testing-library/react";
+import { BrowserRouter } from "react-router-dom";
+import Navbar from "@/components/Navbar";
+
+// Helper to render with Router context
+const renderNavbar = () => render(
+  <BrowserRouter>
+    <Navbar />
+  </BrowserRouter>
+);
+
+describe("Navbar Component", () => {
+
+  beforeEach(() => {
+    localStorage.clear();
+    document.documentElement.classList.remove("dark");
+  });
+
+  it("renders brand name and nav links", () => {
+    renderNavbar();
+    expect(screen.getByText("UniLoot")).toBeInTheDocument();
+    expect(screen.getByText("Home")).toBeInTheDocument();
+    expect(screen.getByText("Browse")).toBeInTheDocument();
+    expect(screen.getByText("Sell")).toBeInTheDocument();
+  });
+
+  it("renders Sign In and Sign Up buttons", () => {
+    renderNavbar();
+    expect(screen.getByRole("button", { name: /sign in/i })).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: /sign up/i })).toBeInTheDocument();
+  });
+
+  it("toggles mobile menu visibility", () => {
+    renderNavbar();
+    const menuButton = screen.getByRole("button", { name: "" }); // the menu (hamburger) icon button
+    fireEvent.click(menuButton);
+    expect(screen.getByText("Home")).toBeVisible();
+    fireEvent.click(menuButton);
+    expect(screen.queryByText("Home")).toBeInTheDocument(); // still in DOM but hidden
+  });
+
+  it("toggles theme between light and dark", () => {
+    renderNavbar();
+    const themeButton = screen.getAllByRole("button").find(btn => btn.innerHTML.includes("svg"));
+    expect(document.documentElement.classList.contains("dark")).toBe(false);
+    fireEvent.click(themeButton!);
+    expect(document.documentElement.classList.contains("dark")).toBe(true);
+    fireEvent.click(themeButton!);
+    expect(document.documentElement.classList.contains("dark")).toBe(false);
+  });
+
+  it("stores theme preference in localStorage", () => {
+    renderNavbar();
+    const themeButton = screen.getAllByRole("button").find(btn => btn.innerHTML.includes("svg"));
+    fireEvent.click(themeButton!);
+    expect(localStorage.getItem("theme")).toBe("dark");
+  });
+});

frontend/src/__tests__/SignIn.test.tsx

@@ -0,0 +1,122 @@
+import { render, screen, fireEvent, waitFor } from "@testing-library/react";
+import { vi } from "vitest";
+import SignIn from "../pages/Signin";
+import { BrowserRouter } from "react-router-dom";
+import { mockLogin } from "../lib/api";
+
+// Mock toast
+vi.mock("../hooks/use-toast", () => ({
+  toast: vi.fn(),
+}));
+
+// Mock the API
+vi.mock("../lib/api", async () => {
+  const actual = await vi.importActual("../lib/api");
+  return {
+    ...actual,
+    mockLogin: vi.fn(),
+  };
+});
+
+describe("SignIn Component", () => {
+  const renderWithRouter = () =>
+    render(
+      <BrowserRouter>
+        <SignIn />
+      </BrowserRouter>
+    );
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  test("renders all form fields", () => {
+    renderWithRouter();
+
+    expect(screen.getByLabelText(/email/i)).toBeInTheDocument();
+    expect(screen.getByLabelText(/password/i)).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: /sign in/i })).toBeInTheDocument();
+  });
+
+  test("shows validation errors for empty submission", async () => {
+    renderWithRouter();
+
+    fireEvent.click(screen.getByRole("button", { name: /sign in/i }));
+
+    await waitFor(() => {
+      expect(screen.getByText(/email is required/i)).toBeInTheDocument();
+      expect(screen.getByText(/password is required/i)).toBeInTheDocument();
+    });
+  });
+
+  test("shows error for invalid email", async () => {
+    renderWithRouter();
+
+    fireEvent.change(screen.getByLabelText(/email/i), {
+      target: { value: "invalidemail" },
+    });
+    fireEvent.change(screen.getByLabelText(/password/i), {
+      target: { value: "password123" },
+    });
+
+fireEvent.input(screen.getByLabelText(/email/i), {
+  target: { value: "invalid-email" },
+});
+fireEvent.input(screen.getByLabelText(/password/i), {
+  target: { value: "password123" },
+});
+fireEvent.submit(screen.getByRole("button", { name: /sign in/i }));
+
+// wait for react-hook-form to show validation message
+await screen.findByText(/invalid email address/i);
+
+  });
+
+  test("submits form successfully", async () => {
+    (mockLogin as vi.Mock).mockResolvedValueOnce({
+      success: true,
+      message: "Login successful!",
+      user: { email: "[email protected]", id: "user-1" },
+    });
+
+    renderWithRouter();
+
+    fireEvent.change(screen.getByLabelText(/email/i), {
+      target: { value: "[email protected]" },
+    });
+    fireEvent.change(screen.getByLabelText(/password/i), {
+      target: { value: "password123" },
+    });
+
+    fireEvent.click(screen.getByRole("button", { name: /sign in/i }));
+
+    await waitFor(() => {
+      expect(mockLogin).toHaveBeenCalledWith({
+        email: "[email protected]",
+        password: "password123",
+      });
+    });
+  });
+
+  test("handles API error gracefully", async () => {
+    (mockLogin as vi.Mock).mockRejectedValueOnce({
+      success: false,
+      message: "Invalid credentials",
+    });
+
+    renderWithRouter();
+
+    fireEvent.change(screen.getByLabelText(/email/i), {
+      target: { value: "[email protected]" },
+    });
+    fireEvent.change(screen.getByLabelText(/password/i), {
+      target: { value: "wrongpass" },
+    });
+
+    fireEvent.click(screen.getByRole("button", { name: /sign in/i }));
+
+    await waitFor(() => {
+      expect(mockLogin).toHaveBeenCalled();
+    });
+  });
+});