add some sanity-test checks to pubsub

packages/pubsub/src/__tests__/index.ts

@@ -1,6 +1,42 @@
 import { InMemoryPubSub } from "../index";
 
-describe("pubsub", () => {
+describe("InMemoryPubSub", () => {
+  test("subscribe", async () => {
+    const pubsub = new InMemoryPubSub();
+    const messages = (async () => {
+      const messages = [];
+      for await (const message of pubsub.subscribe("topic")) {
+        messages.push(message);
+        if (message === "c") {
+          break;
+        }
+      }
+      return messages;
+    })();
+
+    pubsub.publish("topic", "a");
+    pubsub.publish("topic", "b");
+    pubsub.publish("topic", "c");
+    await expect(messages).resolves.toEqual(["a", "b", "c"]);
+  });
+
+  test("unpublish", async () => {
+    const pubsub = new InMemoryPubSub();
+    const messages = (async () => {
+      const messages = [];
+      for await (const message of pubsub.subscribe("topic")) {
+        messages.push(message);
+      }
+      return messages;
+    })();
+
+    pubsub.publish("topic", "a");
+    pubsub.publish("topic", "b");
+    pubsub.publish("topic", "c");
+    pubsub.unpublish("topic");
+    await expect(messages).resolves.toEqual(["a", "b", "c"]);
+  });
+
   test("close", () => {
     const pubsub = new InMemoryPubSub();
     pubsub.close();