With tests

Author: maskaravivek

app/src/main/java/fr/free/nrw/commons/mwapi/OkHttpJsonApiClient.java

@@ -235,11 +235,8 @@ public Single<Media> getPictureOfTheDay() {
 
         return Single.fromCallable(() -> {
             Response response = okHttpClient.newCall(request).execute();
-            if (response != null && response.body() != null && response.isSuccessful()) {
+            if (response.body() != null && response.isSuccessful()) {
                 String json = response.body().string();
-                if (json == null) {
-                    return null;
-                }
                 MwQueryResponse mwQueryPage = gson.fromJson(json, MwQueryResponse.class);
                 return Media.from(mwQueryPage.query().firstPage());
             }

app/src/main/java/fr/free/nrw/commons/utils/MediaDataExtractorUtil.java

@@ -1,7 +1,6 @@
 package fr.free.nrw.commons.utils;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -34,8 +33,17 @@ public static ArrayList<String> extractCategories(String source) {
      * @return
      */
     public static List<String> extractCategoriesFromList(String source) {
-        String[] categories = source.split("\\|");
-        return Arrays.asList(categories);
+        if (StringUtils.isNullOrWhiteSpace(source)) {
+            return new ArrayList<>();
+        }
+        String[] cats = source.split("\\|");
+        List<String> categories = new ArrayList<>();
+        for (String category : cats) {
+            if (!StringUtils.isNullOrWhiteSpace(category.trim())) {
+                categories.add(category);
+            }
+        }
+        return categories;
     }
 
 }