Add BeVoid.

[inamiy]

I had a case to compare non-Equatable Void, e.g. expect(result.value) == (), so I added BeVoid matcher.
I hope this will work, but haven't added for wrapped cases yet, e.g. Array<()>, Set<()>, etc.

[jeffh]

Hey @inamiy,

Looks good, but I'm trying to see the use case that the compiler couldn't statically know. Could you give a more concrete example use case for this matcher?

Even better, add it to the test case. :)

Other than that, I don't see any reason not to merge it.

[inamiy]

@jeffh
Thanks for reply!
Here's a test code I wrote for next try! conference :)

describe("skipSpaces") {

    let p: Parser<String, ()> = skipSpaces

    it("succeeds") {
        let reply: (input: String, output: ())? = parse(p, " \t\n\rabc")._done
        expect(reply?.input) == "abc"
        expect(reply?.output) == ()
    }

    it("succeeds (no spaces)") {
        let reply: (input: String, output: ())? = parse(p, "123")._done
        expect(reply?.input) == "123"
        expect(reply?.output) == ()
    }

}

I intentionally added type annotations above, but basically they can be omitted.
But if we do so, we will have no idea what type reply?.output will be, and all we can test is using expect(reply?.output).toNot(beNil()), which works fine but it is hard to describe that output actually returns Void.

BTW, test code is already added in BeVoidTest.swift, and I think there's not much to add further.

[inamiy]

Oh I also should mention that above == is actually using the following instead of normal one:

public func ==(lhs: Expectation<()>, rhs: ()) {
    lhs.to(beVoid())
}

[jeffh]

Thanks for the context! Merged

[inamiy]

Thanks! I will use this now :)