android - 在 Kotlin 中测试私有(private)方法

Question

如何在 Kotlin 中测试私有(private)方法？我尝试添加 @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)来自 androidx.annotation.VisibleForTesting但它不会使我的函数私有(private)

这就是我的使用方式

@VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
fun doSomething() {}

[编辑]

我知道我不应该测试 private方法，但现在它总是微不足道的。下面的情况呢。

我有一个 CsvReader 类

class CsvReader(private val inputStream: InputStream, private val separator: String = "\t") {
    fun read(): List<String> {
        return read(inputStream.bufferedReader())
    }
    private fun read(bufferedReader: BufferedReader): List<String> {
        val line = bufferedReader.use { it.readLine() } // `use` is like try-with-resources in Java
        return parse(line)
    }
    private fun parse(line: String): List<String> {
        return line.split(separator)
    }
}

我为它写了测试

class CsvReaderTest {
    private val stream = mock<InputStream>()
    private val reader = CsvReader(stream)
    private val bufferedReader = mock<BufferedReader>()
    @Test
    fun read() {
        whenever(bufferedReader.readLine()).thenReturn("Jakub\tSzwiec")
        reader.read(bufferedReader) shouldEqual listOf("Jakub", "Szwiec")
    }
    @Test
    fun readWhenEmpty() {
        whenever(bufferedReader.readLine()).thenReturn("")
        reader.read(bufferedReader) shouldEqual listOf("")
    }
    @Test
    fun throwIOExceptionWhenReadingProblems() {
        whenever(bufferedReader.readLine()).thenThrow(IOException::class.java)
        val read = { reader.read(bufferedReader) }
        read shouldThrow IOException::class
    }
}

不幸的是，对于测试我需要调用私有(private)函数 fun read(bufferedReader: BufferedReader): List<String>因为当 mock File , file.bufferedReader给 NullPointerException Unable to mock BufferedWriter class in junit

Answer 1

你可以使用java反射:

测试方法:

class ClassUnderTest {
      private fun printGreetings(name: String): String {
        return "Hello, $name"
      }
}

够了:

  private val classUnderTest = spyk(ClassUnderTest()) 

  @Test
    fun `should return greetings`() {
      val method = classUnderTest.javaClass.getDeclaredMethod("printGreetings", String::class.java)
      method.isAccessible = true
      val parameters = arrayOfNulls<Any>(1)
      parameters[0] = "Piotr"

      assertEquals("Hello, Piotr", method.invoke(classUnderTest, *parameters) )
  }