Hello all, I am trying to mock a private function ...

# android

[Billy Newman]

Hello all, I am trying to mock a private function call in kotlin with mockk. Running into the following error, wondering if someone can help.

Class is final. Put @MockKJUnit4Runner on your test or add MockK Java Agent instrumentation to make all classes 'open'

[Billy Newman]

Code

class ClassToTest {
  private fun privateMethod(text: String): String {
    return "Hello $text"
  }
}

class TestClass {

   @Before
   fun setup() {
      MockitoAnnotations.openMocks(this)
   }

   @Test
   fun testSplitNumbers() {
      val clazz = spyk<ClassToTest>()

      val method = clazz.javaClass.getDeclaredMethod("privateMethod", String::class.java)
      method.isAccessible = true
      val result = method.invoke(clazz, "Test") as? String
      Assert.assertEquals("Hello Test", result)
   }
}

[Matt Barnard]

Think @VisibleForTesting annotation may work on the line above privateMethod

[Billy Newman]

I my case I cannot change ClassToTest. In addition I am fairly certain given my research that its possible to use reflection w/ spky/mockk to achieve the decided results w/o modifications to ClassToTest.

[Matt Barnard]

Yeah just a testing annotation...idk in the testSplitNumbers block maybe try every { clazz.privateMethod("Test") } returns "Hello Test"

[Billy Newman]

Thanks, that may work, however that would mock that function, not what I am after

[Vinícius Santos]

Have you tried mock-maker-inline ?

[Billy Newman]

Using testImplementation 'org.mockito:mockito-inline:5.2.0'

[Billy Newman]

Guessing I have something wrong with my setup, not sure what though