kotlin test routine 封装 given，when，then

kotlin_test.kt

fun <T> given(desc: String = "", block: () -> T): TestRoutine<T> {
    return TestRoutine("given: $desc", block)
}

class TestRoutine<T>(
    private val message: String = "",
    private val block: () -> T
) {

    fun <R> when_(desc: String = "", whenBlock: (T) -> R): TestRoutine<R> {
        val block = { whenBlock(block()) }
        return TestRoutine("$message\nwhen: $desc", block)
    }

    fun then(desc: String = "", assertBlock: (T) -> Unit) {
        assertBlock(block())
    }
}