[voraa]

Как то так

async function loadData(apiUrl) {
	const response = await fetch(apiUrl);
	const json =  await response.json();
	return json ; 
}
export default loadData;

import loadData from "./index";
 
it("Список постов", async () => {
  const res = await loadData("https://jsonplaceholder.typicode.com/posts")
  expect(res).toHaveLength(100);
});
 
it("Список пользователей", async () => {
  const res = await loadData("https://jsonplaceholder.typicode.com/users")
  expect(res).toHaveLength(10);
});
 
it("Карточка пользователя", async () => {
    const res = await loadData("https://jsonplaceholder.typicode.com/users/1")
	expect(res).toHaveProperty("id", 1);
});

Можно и так прямо писать

it("Карточка пользователя", async () => {
	expect(await loadData("https://jsonplaceholder.typicode.com/users/1"))
            .toHaveProperty("id", 1);
});