def test_empty_s(): assert delete_all("", "what") == ""
def test_except(): with pytest.raises(ValueError): delete_all(1, 2)
def test_simple_case(): assert delete_all("This is AAAstring and this is AABstring", "AAA") == "This is string and this is AABstring"
def test_multiple_case(): assert delete_all("This is AAAstring and this is also AAAstring", "AAA") == "This is string and this is also string"
def test_empty_what(): assert delete_all("This should stay untouched!", "") == "This should stay untouched!"