diff --git a/resources/assets/tests/scripts/event.test.ts b/resources/assets/tests/scripts/event.test.ts
index 7d22375b..16e59f5f 100644
--- a/resources/assets/tests/scripts/event.test.ts
+++ b/resources/assets/tests/scripts/event.test.ts
@@ -1,14 +1,30 @@
 import * as emitter from '@/scripts/event'
 
 test('add listener and emit event', () => {
-  const mockA = jest.fn()
+  const mockA1 = jest.fn()
+  const mockA2 = jest.fn()
   const mockB = jest.fn()
 
-  emitter.on('a', mockA)
+  emitter.on('a', mockA1)
+  emitter.on('a', mockA2)
   emitter.on('b', mockB)
 
   emitter.emit('a')
 
-  expect(mockA).toBeCalledTimes(1)
+  expect(mockA1).toBeCalledTimes(1)
+  expect(mockA2).toBeCalledTimes(1)
   expect(mockB).not.toBeCalled()
 })
+
+test('not throw for un-existed event', () => {
+  emitter.emit('c')
+})
+
+test('unsubscribe event', () => {
+  const mock = jest.fn()
+
+  const off = emitter.on('c', mock)
+  off()
+
+  expect(mock).not.toBeCalled()
+})