// Frida Kahlo's birthday (6 = July) export const DEFAULT_ARGS = [2020, 6, 6]; const RealDate = Date; const isMocked = val => Boolean(val.mock); export const createFakeDateClass = ctorDefault => { const FakeDate = new Proxy(RealDate, { construct: (target, argArray) => { const ctorArgs = argArray.length ? argArray : ctorDefault; return new RealDate(...ctorArgs); }, apply: (target, thisArg, argArray) => { const ctorArgs = argArray.length ? argArray : ctorDefault; return new RealDate(...ctorArgs).toString(); }, // We want to overwrite the default 'now', but only if it's not already mocked get: (target, prop) => { if (prop === 'now' && !isMocked(target[prop])) { return () => new RealDate(...ctorDefault).getTime(); } return target[prop]; }, getPrototypeOf: target => { return target.prototype; }, // We need to be able to set props so that `jest.spyOn` will work. set: (target, prop, value) => { // eslint-disable-next-line no-param-reassign target[prop] = value; return true; }, }); return FakeDate; }; export const useFakeDate = (...args) => { const FakeDate = createFakeDateClass(args.length ? args : DEFAULT_ARGS); global.Date = FakeDate; }; export const useRealDate = () => { global.Date = RealDate; };