Unit Tests for LocationPickerViewModel (#4846)

* LocationPickerViewModel Unit Tests added

* LocationPickerViewModel Unit Tests added

app/src/test/kotlin/fr/free/nrw/commons/locationpicker/LocationPickerViewModelUnitTests.kt

@@ -0,0 +1,72 @@
+package fr.free.nrw.commons.locationpicker
+
+import android.app.Application
+import androidx.lifecycle.MutableLiveData
+import com.mapbox.mapboxsdk.camera.CameraPosition
+import com.nhaarman.mockitokotlin2.any
+import com.nhaarman.mockitokotlin2.times
+import com.nhaarman.mockitokotlin2.verify
+import com.nhaarman.mockitokotlin2.whenever
+import fr.free.nrw.commons.LocationPicker.LocationPickerViewModel
+import org.junit.Before
+import org.junit.Test
+import org.mockito.Mock
+import org.mockito.Mockito.mock
+import org.mockito.MockitoAnnotations
+import org.powermock.reflect.Whitebox
+import retrofit2.Call
+import retrofit2.Response
+
+class LocationPickerViewModelUnitTests {
+
+    private lateinit var viewModel: LocationPickerViewModel
+
+    @Mock
+    private lateinit var application: Application
+
+    @Mock
+    private lateinit var call: Call<CameraPosition>
+
+    @Mock
+    private lateinit var response: Response<CameraPosition>
+
+    @Mock
+    private lateinit var result: MutableLiveData<CameraPosition>
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+        viewModel = LocationPickerViewModel(application)
+
+        Whitebox.setInternalState(viewModel, "result", result)
+    }
+
+    @Test
+    fun `Test onResponse when response body is null`() {
+        viewModel.onResponse(call, response)
+        verify(call, times(0)).isExecuted
+        verify(response, times(1)).body()
+        verify(result, times(1)).value = null
+    }
+
+    @Test
+    fun `Test onResponse when response body is not null`() {
+        whenever(response.body()).thenReturn(mock(CameraPosition::class.java))
+        viewModel.onResponse(call, response)
+        verify(call, times(0)).isExecuted
+        verify(response, times(2)).body()
+        verify(result, times(1)).value = any()
+    }
+
+    @Test
+    fun testOnFailure() {
+        viewModel.onFailure(call, mock(Throwable::class.java))
+        verify(call, times(0)).isExecuted
+    }
+
+    @Test
+    fun testGetResult() {
+        viewModel.result
+    }
+
+}