add shimmer test for trashbin

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

src/androidTest/java/com/owncloud/android/ui/trashbin/TrashbinActivityIT.kt

@@ -84,4 +84,20 @@ class TrashbinActivityIT : AbstractIT() {
 
         screenshot(sut)
     }
+
+    @Test
+    @ScreenshotTest
+    fun loading() {
+        val sut: TrashbinActivity = activityRule.launchActivity(null)
+
+        val trashbinRepository = TrashbinLocalRepository(TestCase.EMPTY)
+
+        sut.trashbinPresenter = TrashbinPresenter(trashbinRepository, sut)
+
+        sut.runOnUiThread { sut.showInitialLoading() }
+
+        shortSleep()
+
+        screenshot(sut)
+    }
 }

src/main/java/com/owncloud/android/ui/trashbin/TrashbinActivity.java

@@ -142,8 +142,7 @@ public class TrashbinActivity extends DrawerActivity implements
         if (trashbinListAdapter.getItemCount() > EMPTY_LIST_COUNT) {
             binding.swipeContainingList.setRefreshing(true);
         } else {
-            binding.loadingContent.setVisibility(View.VISIBLE);
-            binding.list.setVisibility(View.GONE);
+            showInitialLoading();
         }
         trashbinPresenter.loadFolder();
     }
@@ -264,6 +263,12 @@ public class TrashbinActivity extends DrawerActivity implements
         }
     }
 
+    @VisibleForTesting
+    public void showInitialLoading() {
+        binding.loadingContent.setVisibility(View.VISIBLE);
+        binding.list.setVisibility(View.GONE);
+    }
+
     @Override
     public void showError(int message) {
         if (active) {