add tests for EventBus

Signed-off-by: Jari Kolehmainen <jari.kolehmainen@gmail.com>

src/common/__tests__/event-bus.test.ts

@@ -0,0 +1,14 @@
+import { appEventBus, AppEvent } from "../event-bus"
+
+describe("event bus tests", () => {
+  describe("emit", () => {
+    it("emits an event", () => {
+      let event: AppEvent = null
+      appEventBus.on((ev: AppEvent) => {
+        event = ev
+      })
+      appEventBus.emit({name: "foo", action: "bar"})
+      expect(event.name).toBe("foo")
+    })
+  })
+})