def test_multiple_raise_errors() -> None:
with pytest.raises(BippyException) as exc:
(Either.right(42).raise_errors().flat_map(
lambda _: Either.left(BippyException("kaboom 1"))).
flat_map(lambda _: Either.left(BippyException("kaboom 2"))).flat_map(
lambda _: Either.left(BippyException("kaboom 3"))).raise_errors())
assert str(exc.value) == "kaboom 1"
def test_match_types_complex() -> None:
case_1 = Environment[str]().map(lambda s: s + "1")
case_2 = Environment[str]().map(lambda s: s + "2")
case_3 = Environment[str]().map(lambda s: s + "3")
with pytest.raises(TypeMatchException):
unsafe_run(Environment[int]().match_types().provide(42))
# Obviously grotesque use of `match_types`...but we should understand
# its semantics.
assert unsafe_run(Environment[str]().match_types().at_type(
str, case_1).at_type(str, case_2).map(lambda s: s + "foo").at_type(
str, case_3).provide("")) == "1foo"
with pytest.raises(TypeMatchException):
unsafe_run(Environment[dict]().match_types().at_type(
str, case_1).at_type(str, case_2).map(lambda s: s + "foo").at_type(
str, case_3).provide({'ka': 'boom'}))
with pytest.raises(TypeMatchException):
unsafe_run(Environment[str]().match_types().provide(""))
with pytest.raises(TypeMatchException):
unsafe_run(Environment[str]().match_types().at_type(
int, Environment[int]()).provide(""))
assert unsafe_run(Environment[str]().require(
lambda s: len(s) > 5, lambda s: f"String '{s}' is too short.").at_type(
str, case_1).either().provide("foo")) == Either.left(
"String 'foo' is too short.")
def test_tap() -> None:
x = 0
def foo(arg: Either[int, str]) -> None:
nonlocal x
x = arg.map(len).fold(lambda x: x, lambda x: x)
e: Either[int, str] = Either.left(42)
assert e.tap(foo) == e
assert x == 42
e = Either.right("hello")
assert e.tap(foo) == e
assert x == len("hello")
def test_display(capsys: Any) -> None:
e: Either[int, str] = Either.left(42)
assert e.display() == e
captured = capsys.readouterr()
assert captured.out == str(e) + "\n"
assert e.display("Bippy") == e
captured = capsys.readouterr()
assert captured.out == "Bippy:\n" + str(e) + "\n"
e = Either.right("hello")
assert e.display() == e
captured = capsys.readouterr()
assert captured.out == str(e) + "\n"
assert e.display("Bippy") == e
captured = capsys.readouterr()
assert captured.out == "Bippy:\n" + str(e) + "\n"
def test_to_union() -> None:
# The point of this test is to ensure that mypy's type inference works
# properly, ergo we prefer to not parametrize it.
def foo(x: Union[int, str]) -> bool:
return isinstance(x, int) or isinstance(x, str)
e: Either[int, str] = Left(42)
assert e.to_union() == 42
assert foo(e.to_union())
e = Right("hello")
assert e.to_union() == "hello"
assert foo(e.to_union())
# mypy should properly unify Union[NoReturn, X] for all types X.
assert Either.left(42).to_union() + 1 == 43
assert len(Either.right("hello").to_union()) == len("hello")
def test_swap_left(input: A, left_type: Type[A], right_type: Type[B]) -> None:
x: Either[A, B] = Either.left(input)
assert x.swap().swap() == x == Either.right(input).swap()
def test_fold_left() -> None:
x: Either[int, str] = Either.left(42)
assert x.fold(lambda x: x + 1, lambda y: y + "!") == 43
def test_match_left() -> None:
x: Either[int, str] = Either.left(42)
assert x.match(lambda x: x.value + 1, lambda y: y.value + "!") == 43
def test_from_union_left(value: Union[A, B], left_type: Type[A],
right_type: Type[B]) -> None:
assert Either.from_union(value, left_type,
right_type) == Either.left(value)
def test_raise_errors_right_flat_map() -> None:
with pytest.raises(BippyException) as exc:
(Either.right(42).flat_map(
lambda _: Either.left(BippyException("Oh noes!"))).raise_errors())
assert str(exc.value) == "Oh noes!"
def test_raise_errors_exception_on_left() -> None:
with pytest.raises(BippyException) as exc:
Either.left(BippyException("Oh noes!")).raise_errors()
assert str(exc.value) == "Oh noes!"
def test_raise_errors_regular_value() -> None:
with pytest.raises(EitherException) as exc:
Either.left(42).raise_errors()
assert exc.value == EitherException(value=42)
def test_either_left(input: Either[A, NoReturn], expected: Left[A]) -> None:
x = Either.left(input)
assert x == x.to_left() == expected
with pytest.raises(TypeError):
x.to_right() # type: ignore
def test_flatten_left() -> None:
x: Either[str, Either[str, int]] = Either.left("asdf")
assert x.flatten() == Left("asdf")
eqr.EQ2,
eqr.EQ3,
eqr.EQ4,
eqr.EQ5,
eqr.EQ6,
eqr.EQ7,
])
def test_do_notation(equivalence_relation: eqr.Equiv[R, E, A]) -> None:
output_p = unsafe_run(equivalence_relation.p.either().provide(
equivalence_relation.environment))
output_q = unsafe_run(equivalence_relation.q.either().provide(
equivalence_relation.environment))
assert output_p == output_q == equivalence_relation.expected_output
@pytest.mark.parametrize("input", [Either.left(42), Either.right("hello")])
def test_from_either(input: Either[int, str]) -> None:
assert ZIO.from_either(input)._run(()) == input
@pytest.mark.parametrize("input,expected",
[(ZIO.fail("oh noes"), Right(Left("oh noes"))),
(ZIO.succeed(42), Right(Right(42)))])
def test_either(input: ZIO[object, str, int], expected: Either[str,
int]) -> None:
assert input.either()._run(()) == expected
@pytest.mark.parametrize("input,expected",
[(ZIO.succeed(Left("oh noes")), Left("oh noes")),
(ZIO.succeed(Right(42)), Right(42))])
def _f(r: R) -> Either[Union[E, X], AA]:
try:
return self._run(r)
except exc as e:
return Either.left(e)