import * as app from "./App"
import * as math from "./src/math"

describe(" Mock Function provides 3 features",()=>{
    test("3-1.Change the implementation 実装を変更する mockImplementation()",()=>{
        const mock = jest.fn().mockImplementation(() => "bar")

        expect(mock("foo")).toBe("bar")
        expect(mock).toHaveBeenCalledWith("foo")
    })

    test("3-2.Change the implementation 実装を変更する１回",()=>{
        const mock = jest.fn().mockImplementationOnce(() => "bar")

        expect(mock("foo")).toBe("bar")
        expect(mock).toHaveBeenCalledWith("foo")
      
        expect(mock("baz")).toBe(undefined)
        expect(mock).toHaveBeenCalledWith("baz")
    })

    test("3-3.Change the implementation 実装を変更する promise",()=>{
        const mock = jest.fn()
        mock.mockResolvedValue("bar")
      
        expect(mock("foo")).resolves.toBe("bar")
        expect(mock).toHaveBeenCalledWith("foo")
    })
})