const {isEven} = require('./_30s.js');

test('isEven is a Function', () => {
  expect(isEven).toBeInstanceOf(Function);
});
test('4 is even number', () => {
  expect(isEven(4)).toBeTruthy();
});
test('5 is not an even number', () => {
  expect(isEven(5)).toBeFalsy();
});