Add Playwright E2E tests replacing Cypress with MSW integration

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/e2e/specs/login.spec.ts

@@ -0,0 +1,91 @@
+// The Lucia project.
+// Copyright 2026-2026 DSP, inc.  All rights reserved.
+// Authors:
+//   imacat.yang@dsp.im (imacat), 2026/03/22
+
+import { test, expect } from "@playwright/test";
+
+test.describe("Login Flow", () => {
+  test("renders the login form", async ({ page }) => {
+    await page.goto("/login");
+    await expect(page.getByRole("heading", { name: "LOGIN", exact: true }).first()).toBeVisible();
+    await expect(page.locator("#account")).toBeVisible();
+    await expect(page.locator("#password")).toBeVisible();
+    await expect(page.locator("#login_btn_main_btn")).toBeDisabled();
+  });
+
+  test("login button is disabled when fields are empty", async ({
+    page,
+  }) => {
+    await page.goto("/login");
+    await expect(page.locator("#login_btn_main_btn")).toBeDisabled();
+
+    // Only username filled - still disabled
+    await page.locator("#account").fill("testuser");
+    await expect(page.locator("#login_btn_main_btn")).toBeDisabled();
+  });
+
+  test("login button enables when both fields are filled", async ({
+    page,
+  }) => {
+    await page.goto("/login");
+    await page.locator("#account").fill("testadmin");
+    await page.locator("#password").fill("password123");
+    await expect(page.locator("#login_btn_main_btn")).toBeEnabled();
+  });
+
+  test("successful login redirects to /files", async ({ page }) => {
+    await page.goto("/login");
+    await page.locator("#account").fill("testadmin");
+    await page.locator("#password").fill("password123");
+    await page.locator("#login_btn_main_btn").click();
+
+    await expect(page).toHaveURL(/\/files/);
+  });
+
+  test("failed login shows error message", async ({ page }) => {
+    // Visit login first to load app + MSW
+    await page.goto("/login");
+    await expect(page.locator("#login_btn_main_btn")).toBeVisible();
+    // Override the token endpoint to return 401 via MSW
+    await page.evaluate(() => {
+      const { http, HttpResponse } = window.__msw__;
+      window.__mswWorker__.use(
+        http.post("/api/oauth/token", () =>
+          HttpResponse.json(
+            { detail: "Incorrect username or password" },
+            { status: 401 },
+          ),
+        ),
+      );
+    });
+
+    await page.locator("#account").fill("wronguser");
+    await page.locator("#password").fill("wrongpass");
+    await page.locator("#login_btn_main_btn").click();
+
+    await expect(
+      page.getByText("Incorrect account or password"),
+    ).toBeVisible();
+  });
+
+  test("toggles password visibility", async ({ page }) => {
+    await page.goto("/login");
+    await page.locator("#password").fill("secret123");
+    await expect(
+      page.locator("#password"),
+    ).toHaveAttribute("type", "password");
+
+    // Click the eye icon to show password
+    await page.locator('label[for="passwordt"] span.cursor-pointer').click();
+    await expect(
+      page.locator("#password"),
+    ).toHaveAttribute("type", "text");
+
+    // Click again to hide
+    await page.locator('label[for="passwordt"] span.cursor-pointer').click();
+    await expect(
+      page.locator("#password"),
+    ).toHaveAttribute("type", "password");
+  });
+});