Mocking 笑话网络 - 我如何不干燥我的格式化程序？

Question

I have a network module to ping a legacy database with data in multiple formats, and I want to standardize it here in the network module before passing it into the application so my application can expect a certain format of data (don't want the old, poor formatting polluting my business logic). I'm struggling with how to pass mock data through as this network module, specifically as it relates to the formatter. Here's what I mean:

// User API Network Module
// UserAPI.ts
export const getUser = (uid: String, callback: (GetUserResponse) => void): void => {
  // Do network call here and format the data into a typescript type
  // matching the GetUserResponse structure by business logic expects
  callback(formattedData)
}

In my test file, I can mock this call easily with:

import { getUser } from "./UserAPI"
jest.mock("./UserAPI", () => ({
  getUser: (uid: String, callback: (GetUserResponse) => void) => {
    const mockedUserData = require("./mockUser.json")
    // But how do I format it here?
    return formattedMockedUserData
  },
}))

I can create a formatter function in my UserAPI.ts file, export it, and run it in the jest mock, but I'm wondering if that's a best practice because it technically leaks the UserAPI implementation details. And I point that out only because no other file cares about how UserAPI formats things except UserAPI . If I have to leak it for testing purposes, I'll do that. But is there a better way to mock the network call and run it through a formatter without exposing additional implementation details?

And please be gentle on my typescript - I come from both a JS and strongly typed background, but this is my first venture into using typescript:)

Answer 1

Even though it's not used multiple places extract it - following Single Responsibility Principle - into its own construct. You test all formatting logic in Formmater Test not in User API Test. Additionally you can test the integration of Formatter with User API in an Integration Test.