script2.test.js

const fetch = require('node-fetch');
const swapi = require('./script2');

it('calls swapi to get people', () => {
    expect.assertions(1)
    return swapi.getPeople(fetch).then(data => {
        expect(data.count).toEqual(87);
    })
})

it('calls swapi to get people with a promise', () => {
    expect.assertions(2)
    return swapi.getPeoplePromise(fetch).then(data=>{
        expect(data.count).toEqual(87)
        expect (data.results.length).toBeGreaterThan(5)
    })
})

it('getPeople returns count and results', () =>{
    const mockFetch = jest.fn()
    .mockReturnValue(Promise.resolve({
        json: () => Promise.resolve({
            count: 87,
            results: [0,1,2,3,4,5]
        })
    }))
    expect.assertions(4)
    return swapi.getPeoplePromise(mockFetch).then(data => {
        // what did mockFetch do inside swapi.getPeoplePromise function
        expect(mockFetch.mock.calls.length).toBe(1);
        expect(mockFetch).toBeCalledWith('http://swapi.py4e.com/api/people')
        expect(data.count).toEqual(87)
        expect (data.results.length).toBeGreaterThan(5)
    })
})