Fixed the issue added tests (#4933)

app/src/main/java/fr/free/nrw/commons/explore/depictions/DepictsClient.kt

@@ -51,26 +51,42 @@ class DepictsClient @Inject constructor(private val depictsInterface: DepictsInt
         flatMap(::getEntities)
         .map { entities ->
             entities.entities().values.map { entity ->
-                if (entity.descriptions().byLanguageOrFirstOrEmpty() == "") {
+                mapToDepictItem(entity)
-                    val entities: Entities = getEntities(entity[WikidataProperties.INSTANCE_OF]
-                        .toIds()[0]).blockingGet()
-                    val nameAsDescription = entities.entities().values.first().labels()
-                        .byLanguageOrFirstOrEmpty()
-                    DepictedItem(
-                        entity,
-                        entity.labels().byLanguageOrFirstOrEmpty(),
-                        nameAsDescription
-                    )
-                } else {
-                    DepictedItem(
-                        entity,
-                        entity.labels().byLanguageOrFirstOrEmpty(),
-                        entity.descriptions().byLanguageOrFirstOrEmpty()
-                    )
-                }
             }
         }
 
+    /**
+     * Convert different entities into DepictedItem
+     */
+    private fun mapToDepictItem(entity: Entities.Entity): DepictedItem {
+        return if (entity.descriptions().byLanguageOrFirstOrEmpty() == "") {
+            val instanceOfIDs = entity[WikidataProperties.INSTANCE_OF]
+                .toIds()
+            if (instanceOfIDs.isNotEmpty()) {
+                val entities: Entities = getEntities(instanceOfIDs[0]).blockingGet()
+                val nameAsDescription = entities.entities().values.first().labels()
+                    .byLanguageOrFirstOrEmpty()
+                DepictedItem(
+                    entity,
+                    entity.labels().byLanguageOrFirstOrEmpty(),
+                    nameAsDescription
+                )
+            } else {
+                DepictedItem(
+                    entity,
+                    entity.labels().byLanguageOrFirstOrEmpty(),
+                    ""
+                )
+            }
+        } else {
+            DepictedItem(
+                entity,
+                entity.labels().byLanguageOrFirstOrEmpty(),
+                entity.descriptions().byLanguageOrFirstOrEmpty()
+            )
+        }
+    }
+
     /**
      * Tries to get Entities.Label by default language from the map.
      * If that returns null, Tries to retrieve first element from the map.

app/src/test/kotlin/fr/free/nrw/commons/explore/depictions/DepictsClientTest.kt

@@ -3,6 +3,7 @@ package fr.free.nrw.commons.explore.depictions
 import com.nhaarman.mockitokotlin2.mock
 import com.nhaarman.mockitokotlin2.whenever
 import depictSearchItem
+import entity
 import fr.free.nrw.commons.mwapi.Binding
 import fr.free.nrw.commons.mwapi.Result
 import fr.free.nrw.commons.mwapi.SparqlResponse
@@ -15,6 +16,7 @@ import org.junit.Test
 import org.mockito.Mock
 import org.mockito.MockitoAnnotations
 import org.wikipedia.wikidata.*
+import java.lang.reflect.Method
 
 class DepictsClientTest {
 
@@ -108,4 +110,49 @@ class DepictsClientTest {
                     emptyList(), false, "Q10")
             ))
     }
+
+    @Test
+    fun `Test mapToDepictItem when description is not empty`() {
+        val method: Method = DepictsClient::class.java.getDeclaredMethod(
+            "mapToDepictItem",
+            Entities.Entity::class.java
+        )
+        method.isAccessible = true
+        method.invoke(depictsClient, entity(descriptions = mapOf("en" to "Test")))
+    }
+
+    @Test
+    fun `Test mapToDepictItem when description is empty and P31 doesn't exists`() {
+        val method: Method = DepictsClient::class.java.getDeclaredMethod(
+            "mapToDepictItem",
+            Entities.Entity::class.java
+        )
+        method.isAccessible = true
+        method.invoke(depictsClient, entity())
+    }
+
+    @Test
+    fun `Test mapToDepictItem when description is empty and P31 exists`() {
+        val entities = mock<Entities>()
+        val entity = mock<Entities.Entity>()
+        val statementPartial = mock<Statement_partial>()
+        whenever(entity.statements).thenReturn(mapOf("P31" to listOf(statementPartial)))
+        whenever(statementPartial.mainSnak).thenReturn(
+            Snak_partial("test", "P31",
+                DataValue.EntityId(
+                    WikiBaseEntityValue("wikibase-entityid", "Q10", 10L)
+                )
+            )
+        )
+        whenever(depictsInterface.getEntities("Q10")).thenReturn(Single.just(entities))
+        whenever(entities.entities())
+            .thenReturn(mapOf("test" to entity))
+        whenever(entity.id()).thenReturn("Q10")
+        val method: Method = DepictsClient::class.java.getDeclaredMethod(
+            "mapToDepictItem",
+            Entities.Entity::class.java
+        )
+        method.isAccessible = true
+        method.invoke(depictsClient, entity)
+    }
 }