Use local delegated properties with subjects

[raniejade]

So Jetbrains just announced Kotlin's Post 1.0 Roadmap and one of the planned features is local delegated properties. This can be very useful with subjects!

describe(Foo::class) {
    val foo by subject() // using no-arg constructor
}

// or

describe(Foo::class) {
    val foo by subject {
        return@subject Foo(1, 2)
    }
}

This is very similar to RSpec's memoized helpers, heck we can even support let.

describe("foo") {
    var count = 0
    val something by let {
        return@let ++count
    }

    it("it should be 1") {
        assert(something == 1)
    }

    it("it should be 2") {
        assert(something == 2)
    }
}