Spring MockMvcResultHandlersDsl.handle() should take a function as argument

Affects: 5.2.0.RELEASE

MockMvcResultHandlersDsl has a handle(resultHandler: ResultHandler) method. This method is useful, for example when the controller returns a StreamingResponseBody as the body value, in order to be able to call getAsyncResult(). ResultHandler is a functional interface. But since it's being used as the argument of a Kotlin method here, using it requires using the following code:

    andDo {
        handle(ResultHandler { it.asyncResult })
    }

Instead of the more idiomatic

    andDo {
        handle { it.asyncResult }
    }

This can of course be fixed by introducing my own extension function on MockMvcResultHandlersDsl:

fun MockMvcResultHandlersDsl.handle(handler: (result: MvcResult) -> Unit) = handle(ResultHandler { handler(it) })

But I think I shouldn't have to do that, and handle() should have taken a function as argument instead of a ResultHandler in the first place.

It would be nice if a handle(handler: (result: MvcResult) -> Unit) overloading method was added to MockMvcResultHandlersDsl. And maybe the other one should be deprecated, too.

Comment From: sdeleuze

@jnizet Is this issue still relevant?

Comment From: jnizet

I can't remember where I used that, but yes, I think it's still relevant.

MockMvcResultHandlersDsl still has a handle() function taking a ResultHandler as argument. Even though this function is probably used quite rarely, I would find it more idiomatic if the argument was a (MvcResult) -> Unit. Adding an overload wouldn't break anything, and wouldn't be dangerous since ResultHandler is explicitly annotated with @FunctionalInterface (so adding an abstract method to the interface would break Java code).

Comment From: sdeleuze

At least with 1.4 it seems that SAM conversion allows to support andDo { handle { it.asyncResult } } syntax natively, so I have just added a test case for it.