Update nextTick() to work with fake timers

Author: johanblumenberg

package-lock.json

@@ -32,6 +32,7 @@
   ],
   "devDependencies": {
     "@types/jasmine": "^2.6.0",
+    "@types/jest": "^24.0.23",
     "@types/lodash": "^4.14.104",
     "@types/node": "^8.0.46",
     "babel-polyfill": "^6.26.0",

package.json

@@ -30,6 +30,10 @@ import {MethodToStub} from "./MethodToStub";
 import {Mocker, MockPropertyPolicy} from "./Mock";
 import {Spy} from "./Spy";
 
+// Keep a reference to the original, in case it is replaced with fake timers
+// by some library like jest or lolex
+const originalSetTimeout = setTimeout;
+
 export {MockPropertyPolicy} from "./Mock";
 
 export function spy<T>(instanceToSpy: T): T {
@@ -176,7 +180,7 @@ export function defer<T>(): Deferred<T> {
 }
 
 export function nextTick(): Promise<void> {
-    return new Promise(resolve => setTimeout(() => setImmediate(resolve), 0));
+    return new Promise(resolve => originalSetTimeout(() => setImmediate(resolve), 0));
 }
 
 // Export default object with all members (ember-browserify doesn't support named exports).

src/ts-mockito.ts

@@ -27,4 +27,25 @@ describe("nextTick", () => {
         await nextTick();
         expect(done).toBe(true);
     });
+
+    if (typeof jest !== "undefined") {
+        describe('with fake timers', () => {
+            beforeEach(() => {
+                jest.useFakeTimers();
+            });
+
+            afterEach(() => {
+                jest.useRealTimers();
+            });
+            
+            it('should execute after setImmediate()', async () => {
+                let done = false;
+        
+                setImmediate(() => done = true);
+        
+                await nextTick();
+                expect(done).toBe(true);
+            });    
+        });
+    }
 });

test/nextTick.spec.ts

@@ -15,7 +15,8 @@
     "types": [
       "node",
       "lodash",
-      "jasmine"
+      "jasmine",
+      "jest"
     ]
   }
 }