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from returns.result import Failure, Result, Success
def test_bind():
"""Ensures that bind works."""
def factory(inner_value: int) -> Result[int, str]:
if inner_value > 0:
return Success(inner_value * 2)
return Failure(str(inner_value))
input_value = 5
bound: Result[int, str] = Success(input_value)
assert bound.bind(factory) == factory(input_value)
assert Success(input_value).bind(factory) == factory(input_value)
assert str(bound.bind(factory)) == '<Success: 10>'
input_value = 0
bound2: Result[int, str] = Success(input_value)
assert bound2.bind(factory) == factory(input_value)
assert str(bound2.bind(factory)) == '<Failure: 0>'
def test_left_identity_success():
"""Ensures that left identity works for Success container."""
def factory(inner_value: int) -> Result[int, str]:
return Success(inner_value * 2)
input_value = 5
bound: Result[int, str] = Success(input_value)
assert bound.bind(factory) == factory(input_value)
def test_left_identity_failure():
"""Ensures that left identity works for Failure container."""
def factory(inner_value: int) -> Result[int, int]:
return Failure(6)
input_value = 5
bound: Result[int, int] = Failure(input_value)
assert bound.bind(factory) == Failure(input_value)
assert Failure(input_value).bind(factory) == Failure(5)
assert str(bound) == '<Failure: 5>'
def test_lash_success():
"""Ensures that lash works for Success container."""
def factory(inner_value) -> Result[int, str]:
return Success(inner_value * 2)
bound = Success(5).lash(factory)
assert bound == Success(5)
assert Success(5).lash(factory) == Success(5)
assert str(bound) == '<Success: 5>'
def test_lash_failure():
"""Ensures that lash works for Failure container."""
def factory(inner_value: int) -> Result[str, int]:
return Failure(inner_value + 1)
expected = 6
bound: Result[str, int] = Failure(5)
assert bound.lash(factory) == Failure(expected)
assert Failure(5).lash(factory) == Failure(expected)
assert str(bound.lash(factory)) == '<Failure: 6>'
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