Stubbing / Spy on global.fetch in Deno - unit-testing

Question

I'm just getting into Deno, one of the things I'm a little unsure about is how to stub or create a spy for the global fetch function?
One solution is to simply wrap the fetch in a function which itself can by stubbed or spied on, but that seems like an unnecessary abstraction.
Any help would be much appreciated.

Answer 1

With denock you can mock the return object of the fetch call. Maybe not what you want but now you can test without a real call to the server.
https://deno.land/x/denock#0.2.0
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { denock } from "https://deno.land/x/denock/mod.ts";
// function to test
async function fetchFromServer() {
const urlObject = new URL("https://jsonplaceholder.typicode.com/todos");
const response = await fetch(urlObject, {
method: "POST",
headers: new Headers({
"content-type": "application/json",
}),
body: JSON.stringify({
userId: 2,
id: 23024,
title: "delectus aut autem",
completed: false,
}),
});
return await response.json();
}
// mock return
denock({
method: "POST",
protocol: "https",
host: "jsonplaceholder.typicode.com",
headers: [
{
header: "content-type",
value: "application/json",
},
],
path: "/todos",
requestBody: {
userId: 2,
id: 23024,
title: "delectus aut autem",
completed: false,
},
replyStatus: 201,
responseBody: { example: "My mocked response" },
});
// test
Deno.test("fetch", async () => {
const actual = await fetchFromServer();
assertEquals({ example: "My mocked response" }, actual);
});