Is there some way to assert that a function does n...

# atrium

[charleskorn]

Is there some way to assert that a function does not throw?

[robstoll]

Do you still need such a function? I agree with Kevin that usually such a use case should be handled by the test framework but let me know if you have a different use case and I can help you with a corresponding assertion function

[charleskorn]

In my case I have some test cases that should throw (so I use assert({ ... }).toThrow<...>()), but I want to also make it clear for other cases that they should not throw - I can imply that it should succeed by just calling the function, but something like assert({ ... }).toNotThrow() makes it really clear what my intention is

[charleskorn]

(I’m testing an initialiser block that does some validation, so it doesn’t make sense to make an assertion about the return value)

[robstoll]

In the simplest form you can use the following:

fun <T : Throwable> Assert<T>.notToThrow () = this

[charleskorn]

That won’t quite work - if I have a Throwable, then it’s already thrown

[charleskorn]

I need an assertion on a lambda

[robstoll]

Ah... sorry, I am writing from my phone and did not have the code at hand. Make the above an extension function of: ThrowableThrown.Builder

[charleskorn]

OK, I’ll give that a go

[charleskorn]

Thanks!

[robstoll]

Wait... I am pretty sure you need to check that exception is null

[robstoll]

It's a bit cumbersome on the phone, I'll check it later. Also notice that my slack notifications seem to be broken. Did not get any notice about your question or this reply.

[robstoll]

I guess it's a bit more complicated than I wrote. In the meantime you could use:

fun Assert<() -> Any?>.notToThrow () = subject ()

[robstoll]

Btw. good idea, I opened a feature request:
https://github.com/robstoll/atrium/issues/53

[robstoll]

Here the solution for ThrowableThrownBuilder:

fun ThrowableThrown.Builder.notToThrow() = act()

[robstoll]

0.8.0-alpha contains a notToThrow() function

[charleskorn]

Great, I’ll try that now