test(extension): cover background.js message routing and options.js session UI (#7497)

background.js (the service-worker onMessage router) and options.js (the
options-page controller) had no unit tests, unlike auth.js and content.js.
A regression in either -- background.js returning false instead of true and
silently breaking every async response, or refreshSettings() misclassifying an
expired session as valid -- would only surface by manually loading the unpacked
extension.

Add extension-background.test.ts and extension-options.test.ts using the vm
Script/createContext technique extension-content.test.ts established. Both files
statically import from auth.js, which a plain vm Script cannot execute, so the
import line is stripped and the handlers/auth helpers are injected as context
globals (the host Error is shared so 'error instanceof Error' matches the
single-realm extension). Covers background.js's pull-context/logout dispatch,
its Error-vs-stringified error mapping, and the unrecognized/nullish return
false paths; and options.js's refreshSettings() three display branches, the
conditional token-store submit path, and the logout error-recovery fallback.

Closes #7461

Co-authored-by: bitfathers94 <237535319+bitfathers94@users.noreply.github.com>

Author: bitfathers94

test/unit/extension-background.test.ts

@@ -0,0 +1,169 @@
+import { readFileSync } from "node:fs";
+import { Script, createContext } from "node:vm";
+import { describe, expect, it, vi } from "vitest";
+
+// background.js statically imports its two handlers from ./auth.js. The vm `Script` runner cannot
+// execute a top-level ESM `import`, so we strip that line and inject stubbed handlers as context
+// globals -- the free identifiers `requestPullContext`/`logoutExtensionSession` resolve from them.
+// This mirrors content.js's `__LOOPOVER_EXTENSION_TEST__` seam while keeping background.js's real
+// message-routing and error-to-response mapping (lines 3-8) under test.
+const backgroundSource = readFileSync(
+  "apps/loopover-extension/background.js",
+  "utf8",
+).replace(/^import\s*\{[\s\S]*?\}\s*from\s*["']\.\/auth\.js["'];?\n?/, "");
+
+const flush = () => new Promise((resolve) => setTimeout(resolve, 0));
+
+describe("extension background message router", () => {
+  it("resolves loopover:pull-context via requestPullContext and responds { ok: true, payload }", async () => {
+    const requestPullContext = vi.fn(async () => ({ panels: [] }));
+    const logoutExtensionSession = vi.fn();
+    const { listener } = loadBackground({
+      requestPullContext,
+      logoutExtensionSession,
+    });
+    const sendResponse = vi.fn();
+
+    const message = {
+      type: "loopover:pull-context",
+      owner: "JSONbored",
+      repo: "loopover",
+      pullNumber: 148,
+    };
+    const returned = listener(message, {}, sendResponse);
+    await flush();
+
+    expect(returned).toBe(true);
+    expect(requestPullContext).toHaveBeenCalledWith(message);
+    expect(logoutExtensionSession).not.toHaveBeenCalled();
+    expect(sendResponse).toHaveBeenCalledWith({
+      ok: true,
+      payload: { panels: [] },
+    });
+  });
+
+  it("resolves loopover:logout via logoutExtensionSession and responds { ok: true, payload }", async () => {
+    const requestPullContext = vi.fn();
+    const logoutExtensionSession = vi.fn(async () => ({ ok: true }));
+    const { listener } = loadBackground({
+      requestPullContext,
+      logoutExtensionSession,
+    });
+    const sendResponse = vi.fn();
+
+    const returned = listener({ type: "loopover:logout" }, {}, sendResponse);
+    await flush();
+
+    expect(returned).toBe(true);
+    expect(logoutExtensionSession).toHaveBeenCalledTimes(1);
+    expect(requestPullContext).not.toHaveBeenCalled();
+    expect(sendResponse).toHaveBeenCalledWith({
+      ok: true,
+      payload: { ok: true },
+    });
+  });
+
+  it("maps a rejected Error to { ok: false, error: message }", async () => {
+    const requestPullContext = vi.fn(async () => {
+      throw new Error("pull context unavailable");
+    });
+    const { listener } = loadBackground({
+      requestPullContext,
+      logoutExtensionSession: vi.fn(),
+    });
+    const sendResponse = vi.fn();
+
+    listener({ type: "loopover:pull-context" }, {}, sendResponse);
+    await flush();
+
+    expect(sendResponse).toHaveBeenCalledWith({
+      ok: false,
+      error: "pull context unavailable",
+    });
+  });
+
+  it("maps a rejected non-Error value to { ok: false, error: String(value) }", async () => {
+    const logoutExtensionSession = vi.fn(async () => {
+      // eslint-disable-next-line no-throw-literal
+      throw "session gone";
+    });
+    const { listener } = loadBackground({
+      requestPullContext: vi.fn(),
+      logoutExtensionSession,
+    });
+    const sendResponse = vi.fn();
+
+    listener({ type: "loopover:logout" }, {}, sendResponse);
+    await flush();
+
+    expect(sendResponse).toHaveBeenCalledWith({
+      ok: false,
+      error: "session gone",
+    });
+  });
+
+  it("returns false for an unrecognized message type without dispatching either handler", () => {
+    const requestPullContext = vi.fn();
+    const logoutExtensionSession = vi.fn();
+    const { listener } = loadBackground({
+      requestPullContext,
+      logoutExtensionSession,
+    });
+    const sendResponse = vi.fn();
+
+    expect(listener({ type: "loopover:unknown" }, {}, sendResponse)).toBe(
+      false,
+    );
+    expect(requestPullContext).not.toHaveBeenCalled();
+    expect(logoutExtensionSession).not.toHaveBeenCalled();
+    expect(sendResponse).not.toHaveBeenCalled();
+  });
+
+  it("returns false for a nullish message without dispatching either handler", () => {
+    const requestPullContext = vi.fn();
+    const logoutExtensionSession = vi.fn();
+    const { listener } = loadBackground({
+      requestPullContext,
+      logoutExtensionSession,
+    });
+
+    expect(listener(null, {}, vi.fn())).toBe(false);
+    expect(requestPullContext).not.toHaveBeenCalled();
+    expect(logoutExtensionSession).not.toHaveBeenCalled();
+  });
+});
+
+function loadBackground(handlers: {
+  requestPullContext: (...args: unknown[]) => unknown;
+  logoutExtensionSession: (...args: unknown[]) => unknown;
+}) {
+  let listener:
+    | ((
+        message: unknown,
+        sender: unknown,
+        sendResponse: (response: unknown) => void,
+      ) => unknown)
+    | undefined;
+  const context: Record<string, unknown> = {
+    // Share the host Error so background.js's `error instanceof Error` matches the errors our stubs
+    // throw -- a contextified vm has its own Error intrinsic, unlike the extension's single realm.
+    Error,
+    chrome: {
+      runtime: {
+        onMessage: {
+          addListener: (fn: typeof listener) => {
+            listener = fn;
+          },
+        },
+      },
+    },
+    requestPullContext: handlers.requestPullContext,
+    logoutExtensionSession: handlers.logoutExtensionSession,
+  };
+  context.globalThis = context;
+  const vmContext = createContext(context);
+  new Script(backgroundSource).runInContext(vmContext);
+  if (!listener)
+    throw new Error("background.js did not register an onMessage listener");
+  return { listener };
+}