use flush to fix tests

server/client.test.ts

@@ -6,15 +6,16 @@ const hostname = "0.0.0.0";
 const port = 8042;
 const href = `ws://${hostname}:${port}`;
 
-async function connect(url: string): Promise<[WebSocket, string[]]> {
+function connect(url: string): Promise<[WebSocket, string[]]> {
-	return new Promise((resolve) => {
+	return new Promise((resolve, reject) => {
 		const messages: string[] = [];
 		const socket = new WebSocket(url);
 
+		socket.onopen = () => resolve([socket, messages]);
+		socket.onerror = (error) => reject(error);
 		socket.onmessage = ({ data }) => {
 			messages.push(data);
 		};
-		socket.onopen = () => resolve([socket, messages]);
 	});
 }
 
@@ -41,12 +42,18 @@ function setup(
 	};
 }
 
+function flush(): Promise<void> {
+	return new Promise((resolve) => setTimeout(resolve, 0));
+}
+
 Deno.test(
 	"broadcasts a message on connect to all clients",
 	setup(async () => {
 		const [s1, m1] = await connect(href);
 		const [s2, m2] = await connect(href);
 
+		await flush();
+
 		assertEquals(m1, ["1 has joined!", "2 has joined!"]);
 		assertEquals(m2, ["2 has joined!"]);
 
@@ -62,6 +69,8 @@ Deno.test(
 		const [s2, m2] = await connect(href);
 		const [s3, m3] = await connect(href);
 
+		await flush();
+
 		m1.length = 0;
 		m2.length = 0;
 		m3.length = 0;