fix: use a promise, no function, to implement waitFor

Author: wheresrhys

packages/fetch-mock/src/Route.ts

@@ -202,13 +202,11 @@ class Route {
 
 	waitFor(awaitedRoute: Route) {
 		const { response } = this.config;
-		this.config.response = () => {
-			return new Promise((res) =>
-				awaitedRoute.onRespond(() => {
-					res(response);
-				}),
-			);
-		};
+		this.config.response = new Promise((res) =>
+			awaitedRoute.onRespond(() => {
+				res(response);
+			}),
+		);
 	}
 
 	onRespond(func: () => void) {

packages/fetch-mock/src/__tests__/FetchMock/response-negotiation.test.js

@@ -143,7 +143,7 @@ describe('response negotiation', () => {
 				fm.fetchHandler('http://b.com').then(() => routesCalled.push('b')),
 				fm.fetchHandler('http://a.com').then(() => routesCalled.push('a')),
 			]);
-			expect(routesCalled).toEqual(['a', 'c', 'b']);
+			expect(routesCalled).toEqual(['a', 'b', 'c']);
 		});
 		it('Can chain waits', async () => {
 			fm.route('http://a.com', 200, 'route-a')