A package for performing assertions and providing informative exception messages.
Project description
AssertionLib 2.1.0
A package for performing assertions and providing informative exception messages.
Installation
AssertionLib has no external dependencies and can be installed as following:
PyPi: pip install AssertionLib
GitHub: pip install git+https://github.com/nlesc-nano/AssertionLib
Usage
A comprehensive overview of all available assertion methods is provided in the documentation. A few examples of some basic assertion:
>>> from assertionlib import assertion
# Assert the output of specific callables
>>> assertion.eq(5, 5) # 5 == 5
>>> assertion.lt(5, 6) # 5 < 6
>>> assertion.gt(6, 5) # 5 > 6
>>> assertion.isinstance(5, int)
>>> assertion.hasattr(5, '__init__')
# Simply assert a value
>>> assertion(5 == 5)
>>> assertion(isinstance(5, int))
# Perform an assertion which will raise an AssertionError
>>> assertion.eq(5, 6) # 5 == 6
AssertionError: output = eq(a, b); assert output
exception: AssertionError = AssertionError()
output: bool = False
a: int = 5
b: int = 6
A few examples of AssertionErrors raised due to incorrect method signatures:
>>> from assertionlib import assertion
>>> assertion.len(5)
AssertionError: output = len(obj); assert output
exception: TypeError = TypeError("object of type 'int' has no len()")
output: NoneType = None
obj: int = 5
>>> assertion.eq(5, 5, 5, 5)
AssertionError: output = eq(a, b, _a, _b); assert output
exception: TypeError = TypeError('eq expected 2 arguments, got 4')
output: NoneType = None
a: int = 5
b: int = 5
_a: int = 5
_b: int = 5
A demonstration of the exception parameter. Providing an exception type will assert that the provided exception is raised during/before the assertion process:
>>> from assertionlib import assertion
>>> len(5)
TypeError: object of type 'int' has no len()
>>> assertion.len(5, exception=TypeError) # i.e. len(5) should raise a TypeError
>>> assertion.len([5], exception=TypeError)
AssertionError: output = len(obj); assert output
exception: AssertionError = AssertionError("Failed to raise 'TypeError'")
output: int = 1
obj: list = [5]
Lastly, the output of custom callables can be asserted in one of the following two ways, supplying the callable to AssertionManager.assert() or creating a custom assertion method and adding it to an instance with AssertionManager.add_to_instance():
>>> from assertionlib import assertion
>>> my_fancy_func(a):
... return False
# Approach #1, supply to-be asserted callable to assertion.assert_()
>>> assertion.assert_(my_fancy_func, 5)
AssertionError: output = my_fancy_func(a); assert output
exception: AssertionError = AssertionError()
output: bool = False
a: int = 5
# Approach #2, permanantly add a new bound method using assertion.add_to_instance()
>>> assertion.add_to_instance(my_fancy_func)
>>> assertion.my_fancy_func(5)
AssertionError: output = my_fancy_func(a); assert output
exception: AssertionError = AssertionError()
output: bool = False
a: int = 5
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