def test_will_return_first_repeated_word():
input1 = "aa DDD aA cc ddd ee fff"
actual = first_repeated_word(input1)
assert actual == "aa"
def test_no_repeats_returns_None():
input1 = "aa bb cc ddd ee fff"
actual = first_repeated_word(input1)
assert actual == None
def test_will_not_include_punctuations_in_check():
input1 = "aa DDD bb cc ddd ee fff !DdD,"
actual = first_repeated_word(input1)
assert actual == "ddd"
def test_empty_string_returns_None():
input1 = ""
actual = first_repeated_word(input1)
assert actual == None
def test_function_ignores_upper_and_lower_case():
input1 = "aa DDD bb cc ddd ee fff"
actual = first_repeated_word(input1)
assert actual == "ddd"