function assertEqual(expected, actual) {
    expect(expected).toEqual(actual);
}

function refuteEqual(expected, actual) {
    expect(expected).toNotEqual(actual);
}

function assertEmpty(expected) {
    expect(expected.length).toEqual(0);
}

function refuteEmpty(expected) {
    expect(expected.length).toBeGreaterThan(0);
}

function assertNull(value) {
    expect(value).toBeNull();
}

function refuteNull(value) {
    expect(value).not.toBeNull();
}