helper for mocking responses in puppeteer

useMocks.js

export async function useMocks(page, mocks) {
  await page.setRequestInterception(true);
  page.on("request", async (request) => {
    if (request.postData() && JSON.parse(request.postData()).operationName) {
      const mock = mocks.find(
        (mock) => mock.name === JSON.parse(request.postData()).operationName
      );
      if (mock) {
        await delay(500);
        request.respond({
          content: "application/json",
          headers: { "Access-Control-Allow-Origin": "*" },
          body: JSON.stringify(mock.response),
        });
        return;
      }
    }
    request.continue();
    return;
  });
}

// usage
import puppeteer from "puppeteer"
import { useMocks } from "./useMocks";

let browser = await puppeteer.launch({ headless: false });
let page = await browser.newPage();

useMocks(page, [
  {
    name: "GetCurrentUser",
    response: {
      data: {
        currentUser: {
          id: 1,
          name: "My user",
          __typename: "User"
        }
      }
    }
  },
  {
    name: "UpdateUser",
    response: {
      data: {
        user: {
          id: 1,
          name: "My mutated user",
          __typename: "User"
        }
      }
    }
  }
]);

// continue testing as normal, 
// ...with mocked CurrentUser query and UpdateUser mutations