Mastering React Test-Driven Development

Extracting spy helpers

CustomerForm is not the only component we'll use that will call fetch. In fact, the fetch tests we've written in this chapter will be a common occurrence in our code base. It makes sense to reuse the common code we've used, by pulling it out into its own module:

1. Create a test/spyHelpers.js file and add the following two function definitions, which are exactly the same as what you have at the top of test/CustomerForm.test.js, except this time they're exports:

export const fetchResponseOk = body =>  Promise.resolve({    ok: true,    json: () => Promise.resolve(body)  });export const fetchResponseError = () =>  Promise.resolve({ ok: false });

2. Delete those two definitions from within test/CustomerForm.test.js, and replace them ...