Demo :: Fetch Mock

1.txt

$node --test --experimental-test-coverage

▶ getUserById
  ✔ should fetch user data successfully (4.168291ms)
✔ getUserById (4.678666ms)
ℹ tests 1
ℹ suites 1
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 124.05
ℹ start of coverage report
ℹ ---------------------------------------------------------------
ℹ file           | line % | branch % | funcs % | uncovered lines
ℹ ---------------------------------------------------------------
ℹ user.js        |  66.67 |    50.00 |  100.00 | 6-7 12-14
ℹ user.test.js   | 100.00 |   100.00 |  100.00 | 
ℹ ---------------------------------------------------------------
ℹ all files      |  91.94 |    71.43 |  100.00 | 
ℹ ---------------------------------------------------------------
ℹ end of coverage report

user.js

export async function getUserById(userId) {
    try {
        const response = await fetch(`https://api.example.com/users/${userId}`);
        
        if (!response.ok) {
            throw new Error(`Error: ${response.status} ${response.statusText}`);
        }
        
        const data = await response.json();
        return data;
    } catch (error) {
        console.error('Failed to fetch user:', error);
        return null;
    }
}

user.test.js

import fetchMock from "fetch-mock";
import { getUserById } from "./user.js";
import { test, describe } from "node:test";
import assert from "node:assert";

describe("getUserById", () => {
  test("should fetch user data successfully", async () => {
    // Arrange: Set up the mock response
    const userId = 1;
    const mockResponse = { id: 1, name: "Somkiat", email: "[email protected]" };
    fetchMock
      .mockGlobal()
      .get(`https://api.example.com/users/${userId}`, mockResponse);

    // Act: Call the function
    const result = await getUserById(userId);

    // Assert: Verify the response
    assert.deepStrictEqual(result, mockResponse);
  });

});