chore: establish learning module baseline

OpenMAIC/tests/edit/edit-mode-lock.test.ts

@@ -0,0 +1,155 @@
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import {
+  editLockKey,
+  isEditLockHeldByOther,
+  LOCK_HEARTBEAT_MS,
+  LOCK_STALE_MS,
+  readEditLock,
+  refreshEditLock,
+  releaseEditLock,
+  tryAcquireEditLock,
+} from '@/lib/edit/edit-mode-lock';
+
+class MemoryStorage {
+  private store = new Map<string, string>();
+  get length() {
+    return this.store.size;
+  }
+  getItem(k: string) {
+    return this.store.has(k) ? (this.store.get(k) as string) : null;
+  }
+  setItem(k: string, v: string) {
+    this.store.set(k, v);
+  }
+  removeItem(k: string) {
+    this.store.delete(k);
+  }
+  clear() {
+    this.store.clear();
+  }
+  key(i: number) {
+    return Array.from(this.store.keys())[i] ?? null;
+  }
+}
+
+let original: typeof globalThis.localStorage | undefined;
+
+beforeEach(() => {
+  original = (globalThis as { localStorage?: typeof globalThis.localStorage }).localStorage;
+  Object.defineProperty(globalThis, 'localStorage', {
+    value: new MemoryStorage(),
+    configurable: true,
+    writable: true,
+  });
+});
+
+afterEach(() => {
+  Object.defineProperty(globalThis, 'localStorage', {
+    value: original,
+    configurable: true,
+    writable: true,
+  });
+});
+
+describe('editLockKey', () => {
+  it('is scoped per course id', () => {
+    expect(editLockKey('course-A')).not.toBe(editLockKey('course-B'));
+  });
+});
+
+describe('tryAcquireEditLock', () => {
+  it('grants the lock when nothing is held', () => {
+    expect(tryAcquireEditLock('c1', 'tab-A')).toBe(true);
+    expect(readEditLock('c1')?.tabId).toBe('tab-A');
+  });
+
+  it('grants the lock when our own tab already holds it', () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    expect(tryAcquireEditLock('c1', 'tab-A', 2000)).toBe(true);
+    expect(readEditLock('c1')?.timestamp).toBe(2000);
+  });
+
+  it('refuses when another tab holds a fresh lock', () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    expect(tryAcquireEditLock('c1', 'tab-B', 1000 + LOCK_HEARTBEAT_MS)).toBe(false);
+    // Original owner unchanged.
+    expect(readEditLock('c1')?.tabId).toBe('tab-A');
+  });
+
+  it('steals a stale lock from a crashed tab past LOCK_STALE_MS', () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    expect(tryAcquireEditLock('c1', 'tab-B', 1000 + LOCK_STALE_MS + 1)).toBe(true);
+    expect(readEditLock('c1')?.tabId).toBe('tab-B');
+  });
+
+  it('does not bleed across courses', () => {
+    tryAcquireEditLock('c1', 'tab-A');
+    expect(tryAcquireEditLock('c2', 'tab-B')).toBe(true);
+  });
+});
+
+describe('isEditLockHeldByOther', () => {
+  it('returns false when nobody holds the lock', () => {
+    expect(isEditLockHeldByOther('c1', 'tab-A')).toBe(false);
+  });
+
+  it('returns false when our tab holds the lock', () => {
+    tryAcquireEditLock('c1', 'tab-A');
+    expect(isEditLockHeldByOther('c1', 'tab-A')).toBe(false);
+  });
+
+  it('returns true when another tab holds a fresh lock', () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    expect(isEditLockHeldByOther('c1', 'tab-B', 1000 + LOCK_HEARTBEAT_MS)).toBe(true);
+  });
+
+  it("returns false when the other tab's lock is stale", () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    expect(isEditLockHeldByOther('c1', 'tab-B', 1000 + LOCK_STALE_MS + 1)).toBe(false);
+  });
+});
+
+describe('refreshEditLock', () => {
+  it('updates the timestamp for our tab', () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    refreshEditLock('c1', 'tab-A', 5000);
+    expect(readEditLock('c1')?.timestamp).toBe(5000);
+  });
+
+  it("does not overwrite another tab's lock", () => {
+    tryAcquireEditLock('c1', 'tab-A', 1000);
+    refreshEditLock('c1', 'tab-B', 2000);
+    expect(readEditLock('c1')?.tabId).toBe('tab-A');
+    expect(readEditLock('c1')?.timestamp).toBe(1000);
+  });
+});
+
+describe('releaseEditLock', () => {
+  it('removes the lock when we own it', () => {
+    tryAcquireEditLock('c1', 'tab-A');
+    releaseEditLock('c1', 'tab-A');
+    expect(readEditLock('c1')).toBeNull();
+  });
+
+  it('is a no-op when another tab owns the lock', () => {
+    tryAcquireEditLock('c1', 'tab-A');
+    releaseEditLock('c1', 'tab-B');
+    expect(readEditLock('c1')?.tabId).toBe('tab-A');
+  });
+
+  it('is a no-op when no lock exists', () => {
+    expect(() => releaseEditLock('c1', 'tab-A')).not.toThrow();
+  });
+});
+
+describe('graceful degradation', () => {
+  it('returns null when stored JSON is corrupted', () => {
+    localStorage.setItem(editLockKey('c1'), '{not json');
+    expect(readEditLock('c1')).toBeNull();
+  });
+
+  it('returns null when stored shape is wrong', () => {
+    localStorage.setItem(editLockKey('c1'), JSON.stringify({ wrong: 'shape' }));
+    expect(readEditLock('c1')).toBeNull();
+  });
+});