test: create utility to flush all internal promises

test/Event.spec.ts

@@ -2,6 +2,7 @@ import { slot } from './../src/Slot'
 import { combineEvents, createEventBus } from './../src/Events'
 import { TestChannel } from './TestChannel'
 import { DEFAULT_PARAM } from './../src/Constants'
+import { flushPromises } from './testing-utils';
 
 describe('combineEvents()', () => {
 
@@ -93,7 +94,7 @@ describe('createEventBus()', () => {
             data: 5
         })
 
-        await Promise.resolve() // yied to ts-event-bus internals
+        await flushPromises();
         expect(channel.sendSpy).toHaveBeenCalledWith({
             type: 'response',
             slotName: 'numberToString',

test/Slot.spec.ts

@@ -3,6 +3,7 @@ import { TestChannel } from './TestChannel'
 import { Transport } from './../src/Transport'
 import { DEFAULT_PARAM } from './../src/Constants'
 import { TransportRegistrationMessage } from './../src/Message'
+import { flushPromises } from './testing-utils';
 
 const makeTestTransport = () => {
     const channel = new TestChannel()
@@ -145,9 +146,7 @@ describe('connectSlot', () => {
                 type: 'handler_registered'
             })
 
-            // setTimeout(0) to yield control to ts-event-bus internals,
-            // so that the call to handlers can be processed
-            await new Promise(resolve => setTimeout(resolve, 0))
+            await flushPromises();
 
             // Once a remote handler is registered, both local and remote should be called
             expect(localCalled).toEqual(true)

test/Transport.spec.ts

@@ -1,6 +1,7 @@
 import { Transport } from './../src/Transport'
 import { TransportMessage } from './../src/Message'
 import { TestChannel } from './TestChannel'
+import { flushPromises } from './testing-utils';
 
 const param = 'param'
 
@@ -89,7 +90,7 @@ describe('Transport', () => {
 
             channel.fakeReceive(request)
 
-            await Promise.resolve() // yield to ts-event-bus internals
+            await flushPromises();
             expect(handler).toHaveBeenCalledWith(request.data)
             expect(channel.sendSpy).toHaveBeenLastCalledWith({
                 slotName,
@@ -141,7 +142,7 @@ describe('Transport', () => {
                 }
             }
             channel.fakeReceive(request)
-            await Promise.resolve() // yield to ts-event-bus internals
+            await flushPromises();
             expect(handler).not.toHaveBeenCalled()
         })
 

test/testing-utils.ts

@@ -0,0 +1,6 @@
+/**
+ * Utility to flush current promises during a test when using fake timers
+ */
+export function flushPromises(): Promise<void> {
+    return new Promise(jest.requireActual('timers').setImmediate);
+}