def test_check_instructor_string():
    assert not validator.check_instructors("John Doe")
def test_check_instructor_only_one():
    assert validator.check_instructors(["John Doe"])
def test_check_instructor_empty():
    assert not validator.check_instructors([])
def test_check_instructors():
    assert validator.check_instructors(["John Doe", "Jane Doe"])
def test_check_instructor_string():
    assert not validator.check_instructors("John Doe")
def test_check_instructor_empty():
    assert not validator.check_instructors([])
def test_check_instructor_only_one():
    assert validator.check_instructors(["John Doe"])
def test_check_instructors():
    assert validator.check_instructors(["John Doe", "Jane Doe"])