为什么 Hamcrest arrayWithSize 不能与 Kotlin 一起使用

Question

我正在尝试使用 hamcrest 和 <

测试整数数组的长度

import org.hamcrest.MatcherAssert.assertThat
import org.hamcrest.collection.IsArrayWithSize.arrayWithSize
import org.hamcrest.core.IsEqual.equalTo
import org.hamcrest.core.Is.`is` as Is
…
     val parts = intArrayOf(1, 2, 3)
     assertThat(parts, arrayWithSize(3))
     assertThat(parts, Is(arrayWithSize(3)))
     assertThat(parts, Is(arrayWithSize(equalTo(3))))

据我所知，所有三个断言都应该有效，并且等效的语句也可以在 Java 中工作。但它们不能与 Kotlin 一起使用：

[ERROR] …/Decomposed_Test.kt:[287,14] Type mismatch: inferred type is IntArray but String! was expected
[ERROR] …/Decomposed_Test.kt:[287,21] Type mismatch: inferred type is Matcher<Array<(???..???)>!>! but Boolean was expected
[ERROR] …/Decomposed_Test.kt:[288,14] Type mismatch: inferred type is IntArray but String! was expected
[ERROR] …/Decomposed_Test.kt:[288,21] Type mismatch: inferred type is Matcher<(???..???)>! but Boolean was expected
[ERROR] …/Decomposed_Test.kt:[289,14] Type mismatch: inferred type is IntArray but String! was expected
[ERROR] …/Decomposed_Test.kt:[289,21] Type mismatch: inferred type is Matcher<(???..???)>! but Boolean was expected

这当然是错误的，因为我没有比较字符串。我尝试在断言中添加一些原因以查看是否有帮助：

import org.hamcrest.MatcherAssert.assertThat
import org.hamcrest.collection.IsArrayWithSize.arrayWithSize
import org.hamcrest.core.IsEqual.equalTo
import org.hamcrest.core.Is.`is` as Is
…
     val parts = intArrayOf(1, 2, 3)
     assertThat(/* reason = */ "array has 3 elements", /* actual = */ parts, /* matcher = */ arrayWithSize(3))
     assertThat(/* reason = */ "array has 3 elements", /* actual = */ parts, /* matcher = */ Is(arrayWithSize(3)))
     assertThat(/* reason = */ "array has 3 elements", /* actual = */ parts, /* matcher = */ Is(arrayWithSize(equalTo(3))))

不同的错误消息，但仍然没有帮助：

[ERROR] …/Decomposed_Test.kt:[287,91] Type mismatch: inferred type is IntArray! but Array<(out) TypeVariable(E)!>! was expected
[ERROR] …/Decomposed_Test.kt:[288,91] Type mismatch: inferred type is IntArray! but Array<(out) TypeVariable(E)!>? was expected
[ERROR] …/Decomposed_Test.kt:[288,91] Type mismatch: inferred type is IntArray! but Array<(out) TypeVariable(E)!>! was expected
[ERROR] …/Decomposed_Test.kt:[288,94] Type mismatch: inferred type is Matcher<Array<(out) (???..???)>!>! but Matcher<IntArray!>! was expected
[ERROR] …/Decomposed_Test.kt:[289,91] Type mismatch: inferred type is IntArray! but Array<(out) TypeVariable(E)!>? was expected
[ERROR] …/Decomposed_Test.kt:[289,91] Type mismatch: inferred type is IntArray! but Array<(out) TypeVariable(E)!>! was expected
[ERROR] …/Decomposed_Test.kt:[289,94] Type mismatch: inferred type is Matcher<Array<(out) (???..???)>!>! but Matcher<IntArray!>! was expected

这是为什么？

PS：我对替代框架的建议不感兴趣。

Answer 1

回答我自己的问题（就像我经常做的那样），正确的代码是：

     val parts = intArrayOf(1, 2, 3)
     assertThat(/* actual = */ parts.toTypedArray(), /* matcher = */ arrayWithSize(3))
     assertThat(/* actual = */ parts.toTypedArray(), /* matcher = */ Is(arrayWithSize(3)))
     assertThat(/* actual = */ parts.toTypedArray(), /* matcher = */ Is(arrayWithSize(equalTo(3))))

这种转换是性能杀手，但在单元测试中我不在乎。如果我曾经将主要源代码从 java 转换为 kotlin 这样的东西可能会受到伤害。