wip: first draft for jest test EventManager

src/api/EventManager.spec.ts

@@ -0,0 +1,16 @@
+import { EventManager } from "./EventManager";
+
+// https://stackoverflow.com/questions/51418086/jest-expected-mock-function-to-have-been-called-but-it-was-not-called
+describe('Event Manager', () => {
+    
+    it('addEvent should call appropriate REST APIs', () => {
+        // FIXME: extract to beforeEach
+        const em = new EventManager;
+        const newEntry = EventManager.eventFromDefault()
+        newEntry.state.publishYoutube = false
+
+        expect(em.pu).toHaveBeenCalledTimes(1)
+        expect(client.publish).toHaveBeenCalledTimes(1)
+        expect(client.publish).toBeCalledWith('button/islow', '{true}', {qos: 1})
+    })
+})