When unit testing my ViewModel, list always returns empty - unit-testing

Question

I'm trying to learn unit testing, I have my code factored into an MVVM(i) architecture, but when I run my testParseToList() test function, it always comes back with an empty list and I can't figure out why. I fear it may have something to do with the i part of the MVVM(i) and whether or not I'm correctly mocking my viewmodel. I'm starting with my most simple viewmodel in hopes to get a grasp of the concepts before moving onto my more complex ones.
OfflineViewModelUnitTest.kt
#RunWith(JUnit4::class)
class OfflineViewModelUnitTest {
#get:Rule
val rule = InstantTaskExecutorRule()
#Mock
var offlineViewModel: OfflineViewModel = OfflineViewModel(OfflineInteractorImpl())
#Before
fun setup() {
MockitoAnnotations.initMocks(this)
DaggerOfflineViewModelComponent.builder()
.offlineInteractorImplModule(OfflineInteractorImplModule())
.build()
.inject(offlineViewModel)
// this.offlineViewModel = OfflineViewModel(OfflineInteractorImpl())
}
#Test
fun testParseToList() {
val test = offlineViewModel.parseTextToList("dried bonito extract,\n" +
" ketchup,\n" +
" millet,\n" +
" corn & wheat protein")
val a = "dried bonito extract"
val b = "ketchup"
val c = "millet"
val d = "corn & wheat protein"
val expectedResult = listOf(a, b, c, d)
assertEquals(expectedResult, test)
}
}
OfflineViewModel.kt
class OfflineViewModel(private val offlineInteractor: OfflineInteractor): ViewModel() {
init {
DaggerOfflineViewModelComponent.builder()
.offlineInteractorImplModule(OfflineInteractorImplModule())
.build()
.inject(this)
}
fun parseTextToList(firebaseVisionTextString: String): MutableList<String> {
Log.d("here it is", firebaseVisionTextString)
return offlineInteractor.parseTextToList(firebaseVisionTextString)
}
fun readCsvFromAssetFolder(inputStream: InputStream): List<String>{
return offlineInteractor.readCsvFromAssetFolder(inputStream)
}
}
OfflineInteractorImpl.kt
class OfflineInteractorImpl: OfflineInteractor {
override fun parseTextToList(firebaseVisionTextString: String): MutableList<String> {
val ingredientsList: MutableList<String> = firebaseVisionTextString.split(",").map { it.trim() }.toMutableList()
return ingredientsList
}
override fun readCsvFromAssetFolder(inputStream: InputStream): List<String> {
val csvLine: ArrayList<String> = ArrayList()
var content: Array<String>?
try
{
val br = BufferedReader(InputStreamReader(inputStream))
for (line in br.lines())
{
content = line.split((",").toRegex()).dropLastWhile{ it.isEmpty() }.toTypedArray()
csvLine.add(content[0].substringBefore(";"))
}
br.close()
}
catch (e: IOException) {
e.printStackTrace()
}
return csvLine
}
}
Test Results
java.lang.AssertionError:
Expected :[dried bonito extract, ketchup, millet, corn & wheat protein]
Actual :[]

Answer 1

Like second said, since you mocked offlineViewModel it is going to return an empty string, unless you define something for it to return using when().
Source: https://github.com/mockito/mockito/wiki/FAQ#what-values-do-mocks-return-by-default