The sole argument to raise indicates the exception to be raised. This must be either an exception instance or an exception class (a class that derives from Exception). Try this: test=”abc” if True: raise Exception(test + ‘def’)
So unit testing isn’t really in activesupport. Ruby comes with a typical xunit framework in the standard libs (Test::Unit in ruby 1.8.x, MiniTest in ruby 1.9), and the stuff in activesupport just adds some stuff to it. If you are using Test::Unit/MiniTest assert_raise(Exception) { whatever.merge } if you are using rspec (unfortunately poorly documented, but … Read more
The statement assert can be used for checking conditions at runtime, but is removed if optimizations are requested from Python. The extended form is: assert condition, message and is equivalent to: if __debug__: if not condition: raise AssertionError(message) where __debug__ is True is Python was not started with the option -O. So the statement assert … Read more
A test will fail if it raises any kind of unexpected Exception. You can just invoke foo(7) and you will have tested that no MyError is raised. So, following will suffice: def test_foo3(): foo(7) If you want to be explicit and write an assert statement for this, you can do: def test_foo3(): try: foo(7) except … Read more
As of Python 3, the traceback is stored in the exception, so a simple raise e will do the (mostly) right thing: try: something() except SomeError as e: try: plan_B() except AlsoFailsError: raise e # or raise e from None – see below The traceback produced will include an additional notice that SomeError occurred while … Read more
It has two purposes. jackcogdill has given the first one: It’s used for raising your own errors. if something: raise Exception(‘My error!’) The second is to reraise the current exception in an exception handler, so that it can be handled further up the call stack. try: generate_exception() except SomeException as e: if not can_handle(e): raise … Read more
Asserts should be used to test conditions that should never happen. The purpose is to crash early in the case of a corrupt program state. Exceptions should be used for errors that can conceivably happen, and you should almost always create your own Exception classes. For example, if you’re writing a function to read from … Read more