Reflection - private method

In my test I have:

@Before
fun setUp() {
    savedStateHandle = SavedStateHandle()
    saveImageUseCase = Mockito.mock(SaveImageUseCase::class.java)
    repo = FakeRepository()
    viewModel = AreaEditViewModel(repo, savedStateHandle, saveImageUseCase)
    }

@Test
fun setUpArea() = runTest {
    val method = viewModel.javaClass.getDeclaredMethod("setUpArea", Long::class.java)
    method.isAccessible = true
    method.invoke(viewModel, 2L)

...
    }

in my viewModel:

private suspend fun setUpArea(areaId: Long) {
    repository.getAreaById(areaId).first() {
        savedStateHandle["area"] = it
        true
    }
}

when I run my test I get: com.rachapps.area_feature.viewModel.AreaEditViewModel.setUpArea(long) java.lang.NoSuchMethodException: com.rachapps.area_feature.viewModel.AreaEditViewModel.setUpArea(long) at java.base/java.lang.Class.getDeclaredMethod(Class.java:2707) at com.rachapps.area_feature.viewModel.AreaEditViewModelTest$setUpArea$1.invokeSuspend(AreaEditViewModelTest.kt:61)