metamask-extension/ui/app/helpers/utils/fetch-with-cache.test.js

import assert from 'assert';
import nock from 'nock';
import sinon from 'sinon';
import proxyquire from 'proxyquire';

const fakeStorage = {};
const fetchWithCache = proxyquire('./fetch-with-cache', {
  '../../../lib/storage-helpers': fakeStorage,
}).default;

describe('Fetch with cache', function () {
  beforeEach(function () {
    fakeStorage.getStorageItem = sinon.stub();
    fakeStorage.setStorageItem = sinon.stub();
  });
  afterEach(function () {
    sinon.restore();
    nock.cleanAll();
  });

  it('fetches a url', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .reply(200, '{"average": 1}');

    const response = await fetchWithCache(
      'https://fetchwithcache.metamask.io/price',
    );
    assert.deepStrictEqual(response, {
      average: 1,
    });
  });

  it('returns cached response', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .reply(200, '{"average": 2}');

    fakeStorage.getStorageItem.returns({
      cachedResponse: { average: 1 },
      cachedTime: Date.now(),
    });

    const response = await fetchWithCache(
      'https://fetchwithcache.metamask.io/price',
    );
    assert.deepStrictEqual(response, {
      average: 1,
    });
  });

  it('fetches URL again after cache refresh time has passed', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .reply(200, '{"average": 3}');

    fakeStorage.getStorageItem.returns({
      cachedResponse: { average: 1 },
      cachedTime: Date.now() - 1000,
    });

    const response = await fetchWithCache(
      'https://fetchwithcache.metamask.io/price',
      {},
      { cacheRefreshTime: 123 },
    );
    assert.deepStrictEqual(response, {
      average: 3,
    });
  });

  it('should abort the request when the custom timeout is hit', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .delay(100)
      .reply(200, '{"average": 4}');

    await assert.rejects(
      () =>
        fetchWithCache(
          'https://fetchwithcache.metamask.io/price',
          {},
          { timeout: 20 },
        ),
      { name: 'AbortError', message: 'Aborted' },
    );
  });

  it('throws when the response is unsuccessful', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .reply(500, '{"average": 6}');

    await assert.rejects(() =>
      fetchWithCache('https://fetchwithcache.metamask.io/price'),
    );
  });

  it('throws when a POST request is attempted', async function () {
    nock('https://fetchwithcache.metamask.io')
      .post('/price')
      .reply(200, '{"average": 7}');

    await assert.rejects(() =>
      fetchWithCache('https://fetchwithcache.metamask.io/price', {
        method: 'POST',
      }),
    );
  });

  it('throws when the request has a truthy body', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .reply(200, '{"average": 8}');

    await assert.rejects(() =>
      fetchWithCache('https://fetchwithcache.metamask.io/price', { body: 1 }),
    );
  });

  it('throws when the request has an invalid Content-Type header', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/price')
      .reply(200, '{"average": 9}');

    await assert.rejects(
      () =>
        fetchWithCache('https://fetchwithcache.metamask.io/price', {
          headers: { 'Content-Type': 'text/plain' },
        }),
      { message: 'fetchWithCache only supports JSON responses' },
    );
  });

  it('should correctly cache responses from interwoven requests', async function () {
    nock('https://fetchwithcache.metamask.io')
      .get('/foo')
      .reply(200, '{"average": 9}');
    nock('https://fetchwithcache.metamask.io')
      .get('/bar')
      .reply(200, '{"average": 9}');

    const testCache = {};
    fakeStorage.getStorageItem.callsFake((key) => testCache[key]);
    fakeStorage.setStorageItem.callsFake((key, value) => {
      testCache[key] = value;
    });

    await Promise.all([
      fetchWithCache(
        'https://fetchwithcache.metamask.io/foo',
        {},
        { cacheRefreshTime: 123 },
      ),
      fetchWithCache(
        'https://fetchwithcache.metamask.io/bar',
        {},
        { cacheRefreshTime: 123 },
      ),
    ]);

    assert.deepStrictEqual(
      testCache['cachedFetch:https://fetchwithcache.metamask.io/foo']
        .cachedResponse,
      { average: 9 },
    );
    assert.deepStrictEqual(
      testCache['cachedFetch:https://fetchwithcache.metamask.io/bar']
        .cachedResponse,
      { average: 9 },
    );
  });
});