pytest: raises Decorator from nose (implemented as function and class)

pytest_raises_nose.py

from functools import wraps

# Taken from nosetest: see file nose/tools/nontrivial.py
class raises(object):
    """Test must raise one of expected exceptions to pass.

    Example use::

      @raises(TypeError, ValueError)
      def test_raises_type_error():
          raise TypeError("This test passes")

      @raises(Exception)
      def test_that_fails_by_passing():
          pass

    If you want to test many assertions about exceptions in a single test,
    you may want to use `assert_raises` instead.
    """
    def __init__(self, *exceptions):
        self.exceptions = exceptions
        self.valid = ' or '.join([e.__name__ for e in exceptions])

    def __call__(self, func):
        name = func.__name__
        def newfunc(*args, **kw):
            try:
                func(*args, **kw)
            except self.exceptions:
                pass
            except:
                raise
            else:
                message = "%s() did not raise %s" % (name, self.valid)
                raise AssertionError(message)
        newfunc = wraps(func)(newfunc)
        return newfunc

@raises(ValueError)
def test_bar():
    print("Bar")
    raise ValueError("It works!")


@raises(ValueError)
def test_baz():
    print("Bar")

pytest_raises_nose_as_func.py

from functools import wraps

# Same implementation as with class, but only as a function

# Taken from nosetest: see file nose/tools/nontrivial.py
def raises(*exceptions):
    """Test must raise one of expected exceptions to pass.
    
    Same as rases, but implemented as function, not as class
    """
    valid = ' or '.join([e.__name__ for e in exceptions])

    def decorate(func):
        name = func.__name__
        def newfunc(*arg, **kw):
            try:
                func(*arg, **kw)
            except exceptions:
                pass
            except:
                raise
            else:
                message = "%s() did not raise %s" % (name, valid)
                raise AssertionError(message)
        newfunc = wraps(func)(newfunc)
        return newfunc
    return decorate


@raises(ValueError)
def test_bar():
    print("Bar")
    raise ValueError("It works!")


@raises(ValueError)
def test_baz():
    print("Bar")