import {compose} from './compose'import {identity} from './identity'import {inc} from './inc'import {lensProp} from './lensProp'import {over} from './over'import {set} from './set'import {view} from './view'
const testObj = { a: 1, b: 2, c: 3,}
test('focuses object the specified object property', () => { expect(view(lensProp('a'), testObj)).toEqual(1)})
test('returns undefined if the specified property does not exist', () => { expect(view(lensProp('X'), testObj)).toEqual(undefined)})
test('sets the value of the object property specified', () => { expect(set(lensProp('a'), 0, testObj)).toEqual({ a: 0, b: 2, c: 3, })})
test("adds the property to the object if it doesn't exist", () => { expect(set(lensProp('d'), 4, testObj)).toEqual({ a: 1, b: 2, c: 3, d: 4, })})
test('applies function to the value of the specified object property', () => { expect(over(lensProp('a'), inc, testObj)).toEqual({ a: 2, b: 2, c: 3, })})
test("applies function to undefined and adds the property if it doesn't exist", () => { expect(over(lensProp('X'), identity, testObj)).toEqual({ a: 1, b: 2, c: 3, X: undefined, })})
test('can be composed', () => { const nestedObj = { a: {b: 1}, c: 2, } const composedLens = compose(lensProp('a'), lensProp('b'))
expect(view(composedLens, nestedObj)).toEqual(1)})
test('set s (get s) === s', () => { expect(set(lensProp('a'), view(lensProp('a'), testObj), testObj)).toEqual( testObj )})
test('get (set s v) === v', () => { expect(view(lensProp('a'), set(lensProp('a'), 0, testObj))).toEqual(0)})
test('get (set(set s v1) v2) === v2', () => { expect( view( lensProp('a'), set(lensProp('a'), 11, set(lensProp('a'), 10, testObj)) ) ).toEqual(11)})