Merge pull request #5 from a-bugaj/feat/publish-event-without-any-payload

feat: Publishing the event without any payload

Author: a-bugaj

__tests__/pubSub.test.ts

@@ -177,4 +177,18 @@ describe("PubSub -> Publish method", () => {
         expect(callback).toHaveBeenNthCalledWith(1, data);
         expect(callback).toHaveBeenNthCalledWith(2, []);
     });
+
+    it("Should publish event with empty payload", () => {
+        // given
+        const event = "event.with.empty.payload";
+        const callback = jest.fn();
+        pubSub.subscribe(event, callback);
+
+        // when
+        pubSub.publish(event);
+
+        // then
+        expect(callback).toHaveBeenCalledTimes(1);
+        expect(callback).toHaveBeenCalledWith(undefined);
+    });
 });

__tests__/pubSub.typings.test.ts

@@ -13,14 +13,19 @@ const pubSub = PubSub();
 // publish method
 pubSub.publish<Event, Data>(Event.Random, { name: "John" });
 pubSub.publish<Event.Random, Data>(Event.Random, { name: "John" });
-pubSub.publish<string, Data>("event.with.string.type", { name: "John" });
+pubSub.publish<string, Data>("event.with.string.type.and.payload", { name: "John" });
+pubSub.publish<string>("event.with.string.type", { name: "John" });
 pubSub.publish("event.without.types", []);
 
 // subscribe method
 pubSub.subscribe<Event, Data>(Event.Random, (data) => {
     data.name;
 });
 
+pubSub.subscribe<Event>(Event.Random, () => {
+    // empty payload
+});
+
 pubSub.subscribe<Event.Random, Data>(Event.Random, (data) => {
     data.name;
 });

lib/pubSub.ts

@@ -1,6 +1,6 @@
 import { randomHashKeyGenerator, HashKey } from "./randomHashKeyGenerator";
 
-type Callback<D> = (data: D) => void;
+type Callback<D = unknown> = (data?: D) => void;
 
 interface Subscribers {
     eventName: string;
@@ -15,7 +15,10 @@ export class PubSub {
         this.subscribers = [];
     }
 
-    subscribe = <E extends string, D>(event: E, callback: Callback<D>): HashKey => {
+    subscribe = <E extends string, D = (data?: unknown) => void>(
+        event: E,
+        callback: Callback<D>
+    ): HashKey => {
         const hashKey = randomHashKeyGenerator();
 
         this.subscribers.push({
@@ -36,7 +39,7 @@ export class PubSub {
         this.subscribers = events;
     };
 
-    publish = <E extends string, D>(event: E, data: D): void => {
+    publish = <E extends string, D = unknown>(event: E, data?: D): void => {
         const events = this.subscribers.filter(({ eventName }) => eventName === event);
 
         events.forEach((event) => {