New Base func

lib/events/__tests__/bus.test.ts

@@ -0,0 +1,111 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest'
+import { eventBus } from '../bus'
+import type { JournalEntry } from '@/types'
+
+const fakeEntry = { id: 'e1' } as JournalEntry
+
+beforeEach(() => {
+  eventBus.clear()
+})
+
+describe('EventBus', () => {
+  it('on() subscribes a handler and returns an unsubscribe function', () => {
+    const handler = vi.fn()
+    const unsub = eventBus.on('journal_entry.drafted', handler)
+
+    expect(typeof unsub).toBe('function')
+  })
+
+  it('emit() calls all handlers for that event type', async () => {
+    const handler1 = vi.fn()
+    const handler2 = vi.fn()
+
+    eventBus.on('journal_entry.committed', handler1)
+    eventBus.on('journal_entry.committed', handler2)
+
+    await eventBus.emit({
+      type: 'journal_entry.committed',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+
+    expect(handler1).toHaveBeenCalledWith({ entry: fakeEntry, userId: 'u1' })
+    expect(handler2).toHaveBeenCalledWith({ entry: fakeEntry, userId: 'u1' })
+  })
+
+  it('emit() uses Promise.allSettled — a failing handler does not crash others', async () => {
+    const failingHandler = vi.fn().mockRejectedValue(new Error('boom'))
+    const goodHandler = vi.fn()
+
+    eventBus.on('journal_entry.committed', failingHandler)
+    eventBus.on('journal_entry.committed', goodHandler)
+
+    // Should not throw
+    await eventBus.emit({
+      type: 'journal_entry.committed',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+
+    expect(failingHandler).toHaveBeenCalled()
+    expect(goodHandler).toHaveBeenCalled()
+  })
+
+  it('emit() with no handlers is a no-op', async () => {
+    // Should not throw
+    await eventBus.emit({
+      type: 'journal_entry.drafted',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+  })
+
+  it('unsubscribe removes the handler, future emits do not call it', async () => {
+    const handler = vi.fn()
+    const unsub = eventBus.on('journal_entry.committed', handler)
+
+    unsub()
+
+    await eventBus.emit({
+      type: 'journal_entry.committed',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+
+    expect(handler).not.toHaveBeenCalled()
+  })
+
+  it('clear() removes all handlers', async () => {
+    const handler1 = vi.fn()
+    const handler2 = vi.fn()
+
+    eventBus.on('journal_entry.committed', handler1)
+    eventBus.on('journal_entry.drafted', handler2)
+
+    eventBus.clear()
+
+    await eventBus.emit({
+      type: 'journal_entry.committed',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+    await eventBus.emit({
+      type: 'journal_entry.drafted',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+
+    expect(handler1).not.toHaveBeenCalled()
+    expect(handler2).not.toHaveBeenCalled()
+  })
+
+  it('handlers for different event types do not interfere', async () => {
+    const committedHandler = vi.fn()
+    const draftedHandler = vi.fn()
+
+    eventBus.on('journal_entry.committed', committedHandler)
+    eventBus.on('journal_entry.drafted', draftedHandler)
+
+    await eventBus.emit({
+      type: 'journal_entry.committed',
+      payload: { entry: fakeEntry, userId: 'u1' },
+    })
+
+    expect(committedHandler).toHaveBeenCalledOnce()
+    expect(draftedHandler).not.toHaveBeenCalled()
+  })
+})