Pluggable custom http client wrapper

[MichaelGHSeg]

Creating a pluggable interface to wrap fetch calls, which will allow for custom clients to be used, such as a fetch implementation that supports http proxies.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 6cf70ee

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[silesky]

I like where your heads at. I think instead of implementing our own custom spy logic to keep track of calls, it would be less boilerplate / mantainenance to leverage the existing jest library support for mocks/spies and all sorts of goodies. https://jestjs.io/docs/jest-object

Also, with that jest automatically clears all mock state between tests, so no need to do any reset in a beforeEach().

(See comment below -- could also slightly to tweak this to integrate a MockHttpClient class)
e.g.

import { createTestAnalytics } from './test-helpers/create-test-analytics'
import { createSuccess } from './test-helpers/factories'

describe('disable', () => {
   const mockSend: jest.Mock = jest.fn().mockResolvedValue(createSuccess())
   
   const mockHttpClient: CustomHTTPClient = {
     send: mockSend, 
  }

  it('should dispatch callbacks and emit an http request, even if disabled', async () => {
    const analytics = createTestAnalytics({
      disable: true,
      customClient: mockHttpClient,
    })
    const emitterCb = jest.fn()
    analytics.on('http_request', emitterCb)
    await new Promise((resolve) =>
      analytics.track({ anonymousId: 'foo', event: 'bar' }, resolve)
    )
    expect(emitterCb).toBeCalledTimes(1)
  })

  it('should call fetch if disabled is false', async () => {
    const analytics = createTestAnalytics({
      disable: false,
      customClient: mockHttpClient,
    })
    await new Promise((resolve) =>
      analytics.track({ anonymousId: 'foo', event: 'bar' }, resolve)
    )
    expect(mockSend).toBeCalledTimes(1)
  })
  it('should not call fetch if disabled is true', async () => {
    const analytics = createTestAnalytics({
      disable: true,
      customClient: mockHttpClient,
    })
    await new Promise((resolve) =>
      analytics.track({ anonymousId: 'foo', event: 'bar' }, resolve)
    )
    expect(mockSend).toBeCalledTimes(0)
  })
})

  

[silesky]

I really like where your heads at in general using the mock interface

1. This is not a factory, so I would put it in another file maybe just called mock-http-client.
2. I am not entirely sure this mock is actually necessary... or at least, it can be dramatically simplified -- see earlier earlier comment.

The mock client could just be this:

export class MockHttpClient implements CustomHTTPClient {
  get lastCall() {
    return this.send.mock.lastCall
  }
  get calls() {
     this.send.mock.calls
  }
  send = jest.fn().mockResolvedValue(createSuccess())
}

[silesky]

Superceded by #880