How can I use Mockito to test this function? - unit-testing

Question

I'm trying to test that Permission.REVEAL_NOW returns the method isFeatureRevealNowAvailable.
Heres some code I already tried but didn't succeed with. Any help would be hugely appreciated as always!
Function to test:
class PermissionRepository(private val permissionApi: PermissionApi,
private val appPreferences: AppPreferences) {
fun checkPermission(permission: PermissionType, onPermissionResponse: (Boolean) -> Unit) {
Log.i("Permission", "Checking permission")
when (permission) {
PermissionType.REVEAL_NOW -> {
isFeatureRevealNowAvailable(onPermissionResponse, ::errorHandler)
}
}
}
Attempted solution:
#RunWith(MockitoJUnitRunner::class)
class PermissionRepositoryTest{
#Test
fun checkPermissionTest() {
val mockPermissionRepository = mock(PermissionRepository::class.java)
val mockPermissionApi = mock(PermissionApi::class.java)
val result = mockPermissionRepository.checkPermission(PermissionType.REVEAL_NOW, onPermissionResponse = null)
//Unsure of what to use here AssertThat or Mockito's "when" function
}
}
private fun isFeatureRevealNowAvailable(permissionResponseHandler: (Boolean) -> Unit, permissionError: (Throwable) -> Unit) {
permissionApi.getRevealNowPermission().enqueue(object : Callback<PermissionResponse> {
override fun onFailure(call: Call<PermissionResponse>, t: Throwable) {
permissionResponseHandler(false)
permissionError(t)
}
override fun onResponse(call: Call<PermissionResponse>, response: Response<PermissionResponse>) {
val permissionResult = response.body()?.isRevealNow ?: false
updateUserLocalPermission(PermissionType.REVEAL_NOW, permissionResult)
permissionResponseHandler(permissionResult)
}
})
}

Answer 1

(TL;DR - go to Example)
Since you don't define specifically what you want to test or achieve, I will give some overall tips:
Mocking
Never mock the class you want to test
val mockPermissionRepository = mock(PermissionRepository::class.java)
Mock only what you want to exclude from your test but rely on
Try to avoid mocks whenever it is possible and makes sence, because they simulate a perfect world, not the real behaviour
Test naming
Use proper names to describe what you want to achive with your test. My personal favourite is to start the sentence with the word "should ..."
Example
Two tests I could image to write for your function:
#Test
fun `should invoke reveal permission on PermissionApi when type is REVEAL_NOW`(){
val mockPermissionApi = mock(PermissionApi::class.java)
val permissionRepository = PermissionRepository(mockPermissionApi, mock())
permissionRepository.checkPermission(PermissionType.REVEAL_NOW, onPermissionResponse = {})
verify(mockPermissionApi, times(1)).getRevealNowPermission()
}
#Test
fun `should do nothing when type is not REVEAL_NOW`() {
val mockPermissionApi = mock(PermissionApi::class.java)
val permissionRepository = PermissionRepository(mockPermissionApi, mock())
permissionRepository.checkPermission(PermissionType.ELSE, onPermissionResponse = {})
verify(mockPermissionApi, times(0)).getRevealNowPermission()
}