假设我有一个界面
public interface ICardSuit {
/**short name*/
public String getName();
/** the colour of this card*/
public ICardColour getColour();
}
我决定使用枚举实现:
public enum CardSuit implements ICardSuit {
HEART{
@Override
public ICardColour getColour() {
return CardColour.RED;
}
},
SPADE{
@Override
public ICardColour getColour() {
return CardColour.BLACK;
}
},
DIAMOND{
@Override
public ICardColour getColour() {
return CardColour.RED;
}
},
CLUBS {
@Override
public ICardColour getColour() {
return CardColour.BLACK;
}
}
;
@Override
public String getName() {
return this.name();
}
}
我现在想测试它(使用kotlintest因为我正在开发它的喜好):
class CardSuitTest : FunSpec(){
init {
test("there are exactly four suits"){CardSuit.values().size shouldBe 4}
test("suits implement interface"){CardSuit.values().forEach { it shouldBe instanceOf(ICardSuit::class) }}
test("suits have correct names"){
val suits = CardSuit.values() as Array<out ICardSuit>
suits.forEach { when(it.name){
"HEART" -> it should beTheSameInstanceAs(CardSuit.HEART as ICardSuit)
"SPADE" -> it should beTheSameInstanceAs(CardSuit.SPADE as ICardSuit)
"DIAMOND" -> it should beTheSameInstanceAs(CardSuit.DIAMOND as ICardSuit)
"CLUBS" -> it should beTheSameInstanceAs(CardSuit.CLUBS as ICardSuit)
} }
}
test("suits have correct colours"){
CardSuit.values().forEach { when(it){
CardSuit.HEART,CardSuit.DIAMOND -> it.colour shouldBe CardColour.RED
CardSuit.CLUBS, CardSuit.SPADE -> it.colour shouldBe CardColour.BLACK
} }
}
}
}
我需要投射到ICardSuit
,因为如果我不这样做,编译器就会抱怨
None of the following functions can be called with the arguments supplied.
* T.should(Matcher<T>) where T cannot be inferred for infix fun <T> T.should(matcher: Matcher<T>): Unit defined in io.kotlintest.matchers
* ICardSuit.should((ICardSuit) → Unit) where T = ICardSuit for infix fun <T> T.should(matcher: (T) → Unit): Unit defined in io.kotlintest.matchers
我想保留as Array<out ICardSuit>
,因为这是确保我只访问界面属性的最简单方法,
但我真的不喜欢不得不施放我正在测试的实例。
我能做些什么吗?
是否有特定原因需要使用匹配器beSameInstanceAs
?
你可以这样做:
val suits = CardSuit.values() as Array<out ICardSuite>
suits.forEach {
when (it.name) {
"HEART" -> it shouldBe CardSuit.HEART
"SPADE" -> it shouldBe CardSuit.SPADE
}
}
但是,如果您真的想使用beSameInstanceAs
,您可以:
suits.forEach {
when(it.name) {
"HEART" -> it shouldBeSameInstanceAs CardSuit.HEART
"SPADE" -> it shouldBeSameInstanceAs CardSuit.SPADE
}
}
我真的没有收到编译器的任何抱怨
beTheSameInstanceAs(CardSuit.HEART)
返回Matcher<CardSuit>
,所以它无法匹配任意的ICardSuit
。这是有道理的(虽然Matcher
可能是反变体,你需要协方差)。但是你可以:
beTheSameInstanceAs<ICardSuit>(CardSuit.HEART)
。inline fun <T1, reified T2 : T1> Matcher<T2>.widen() = object : Matcher<T1>() {
override fun test(value: T1) =
if (value is T2)
this.test(value)
else
Result(false, "$value is not a ${T2::class.name}", "$value is a ${T2::class.name}")
}
并打电话
it should beTheSameInstanceAs(CardSuit.HEART).widen()
(我认为类型推断应该在这里工作)。beTheSameInstanceAs(x)
真的可以匹配任何东西,声明一个返回Matcher<Any>
的等效函数:
fun beTheSameInstanceAsAny(x: Any) = beTheSameInstanceAs(x)
// usage
"HEART" -> it should beTheSameInstanceAsAny(CardSuit.HEART)