def test_they_can_be_used_as_a_dict_key():
lookup = {ReadOnce("a"): "success", ReadOnce("b"): "another"}
assert lookup[ReadOnce("a")] == "success"
def test_they_can_be_hashed_if_the_inner_type_can_be():
a = ReadOnce("the same")
b = ReadOnce("the same")
assert hash(a) == hash(b)
def test_they_cant_be_compared_to_other_types():
a = ReadOnce("the same")
b = "the same"
with pytest.raises(RuntimeError):
a != b
def test_they_are_equal_if_the_contents_is():
a = ReadOnce("the same")
b = ReadOnce("the same")
assert a == b
def test_it_returns_the_value_stored():
something = ReadOnce("hello - only once")
assert something.get_contents() == "hello - only once"
def test_they_are_not_equal_if_the_contents_isnt():
a = ReadOnce("the same")
b = ReadOnce("but different")
assert a != b
def test_the_repr_it_returns_indicates_the_type():
something = ReadOnce("Hello!")
assert repr(something) == "ReadOnce<str>"
def test_they_cannot_be_pickled():
contents = ReadOnce("the actual value")
with pytest.raises(RuntimeError):
pickle.dumps(contents)
def test_turning_it_into_a_string_only_works_once():
something = ReadOnce("the actual value")
_first_usage = str(something)
with pytest.raises(ReadTwiceError):
_second_usage = str(something)
def test_it_can_be_used_in_f_strings():
something = ReadOnce("Hello!")
assert f"you said: {something}" == "you said: Hello!"
def test_turning_it_into_a_string_turns_the_underlying_value_into_a_string():
something = ReadOnce("the actual value")
assert str(something) == "the actual value"
def test_an_isinstance_equiv_is_provided():
assert ReadOnce("hello - only once").isinstance(str)
assert ReadOnce(5).isinstance(object)
def test_type_information_can_still_be_accessed():
assert ReadOnce("hello - only once").type == str
assert ReadOnce(5).type == int
def test_the_exception_message_does_not_contain_the_value():
something = ReadOnce("secret")
_first = something.get_contents()
with pytest.raises(ReadTwiceError) as error:
_second = something.get_contents()
assert "secret" not in str(error.value)
def test_it_raise_an_exception_the_second_time_its_read():
something = ReadOnce("hello - only once")
_first = something.get_contents()
with pytest.raises(ReadTwiceError):
_second = something.get_contents()