Refactoring to extract GpsCategoryModel and ensure single-responsibility-principle is maintained in CategoryApi.

app/proguard-rules.txt

@@ -1,5 +1,4 @@
 -dontobfuscate
 -keep class org.apache.http.** { *; }
 -dontwarn org.apache.http.**
--keep class fr.free.nrw.commons.upload.CategoryApi$Page {*;}
 -keep class android.support.v7.widget.ShareActionProvider { *; }

app/src/main/java/fr/free/nrw/commons/caching/CacheController.java

@@ -7,18 +7,25 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import fr.free.nrw.commons.upload.CategoryApi;
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import fr.free.nrw.commons.upload.GpsCategoryModel;
 import timber.log.Timber;
 
+@Singleton
 public class CacheController {
 
+    private final GpsCategoryModel gpsCategoryModel;
+    private final QuadTree<List<String>> quadTree;
     private double x, y;
-    private QuadTree<List<String>> quadTree;
     private double xMinus, xPlus, yMinus, yPlus;
 
     private static final int EARTH_RADIUS = 6378137;
 
-    public CacheController() {
+    @Inject
+    CacheController(GpsCategoryModel gpsCategoryModel) {
+        this.gpsCategoryModel = gpsCategoryModel;
         quadTree = new QuadTree<>(-180, -90, +180, +90);
     }
 
@@ -31,8 +38,8 @@ public class CacheController {
 
     public void cacheCategory() {
         List<String> pointCatList = new ArrayList<>();
-        if (CategoryApi.GpsCatExists.getGpsCatExists()) {
+        if (gpsCategoryModel.getGpsCatExists()) {
-            pointCatList.addAll(CategoryApi.getGpsCat());
+            pointCatList.addAll(gpsCategoryModel.getCategoryList());
             Timber.d("Categories being cached: %s", pointCatList);
         } else {
             Timber.d("No categories found, so no categories cached");
@@ -65,7 +72,7 @@ public class CacheController {
     }
 
     //Based on algorithm at http://gis.stackexchange.com/questions/2951/algorithm-for-offsetting-a-latitude-longitude-by-some-amount-of-meters
-    public void convertCoordRange() {
+    private void convertCoordRange() {
         //Position, decimal degrees
         double lat = y;
         double lon = x;

app/src/main/java/fr/free/nrw/commons/category/CategorizationFragment.java

@@ -39,7 +39,7 @@ import butterknife.ButterKnife;
 import fr.free.nrw.commons.R;
 import fr.free.nrw.commons.di.CommonsDaggerSupportFragment;
 import fr.free.nrw.commons.mwapi.MediaWikiApi;
-import fr.free.nrw.commons.upload.CategoryApi;
+import fr.free.nrw.commons.upload.GpsCategoryModel;
 import fr.free.nrw.commons.utils.StringSortingUtils;
 import fr.free.nrw.commons.utils.ViewUtil;
 import io.reactivex.Observable;
@@ -73,6 +73,7 @@ public class CategorizationFragment extends CommonsDaggerSupportFragment {
     @Inject @Named("prefs") SharedPreferences prefsPrefs;
     @Inject @Named("direct_nearby_upload_prefs") SharedPreferences directPrefs;
     @Inject CategoryDao categoryDao;
+    @Inject GpsCategoryModel gpsCategoryModel;
 
     private RVRendererAdapter<CategoryItem> categoriesAdapter;
     private OnCategoriesSaveHandler onCategoriesSaveHandler;
@@ -253,7 +254,6 @@ public class CategorizationFragment extends CommonsDaggerSupportFragment {
     }
 
     private Observable<CategoryItem> defaultCategories() {
-
         Observable<CategoryItem> directCat = directCategories();
         if (hasDirectCategories) {
             Timber.d("Image has direct Cat");
@@ -287,9 +287,7 @@ public class CategorizationFragment extends CommonsDaggerSupportFragment {
     }
 
     private Observable<CategoryItem> gpsCategories() {
-        return Observable.fromIterable(
+        return Observable.fromIterable(gpsCategoryModel.getCategoryList())
-                CategoryApi.GpsCatExists.getGpsCatExists()
-                        ? CategoryApi.getGpsCat() : new ArrayList<>())
                 .map(name -> new CategoryItem(name, false));
     }
 

app/src/main/java/fr/free/nrw/commons/di/CommonsApplicationModule.java

@@ -13,7 +13,6 @@ import dagger.Module;
 import dagger.Provides;
 import fr.free.nrw.commons.auth.AccountUtil;
 import fr.free.nrw.commons.auth.SessionManager;
-import fr.free.nrw.commons.caching.CacheController;
 import fr.free.nrw.commons.data.DBOpenHelper;
 import fr.free.nrw.commons.location.LocationServiceManager;
 import fr.free.nrw.commons.mwapi.MediaWikiApi;
@@ -117,12 +116,6 @@ public class CommonsApplicationModule {
         return new LocationServiceManager(context);
     }
 
-    @Provides
-    @Singleton
-    public CacheController provideCacheController() {
-        return new CacheController();
-    }
-
     @Provides
     @Singleton
     public DBOpenHelper provideDBOpenHelper(Context context) {

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

@@ -0,0 +1,101 @@
+package fr.free.nrw.commons.mwapi;
+
+import com.google.gson.Gson;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+
+import fr.free.nrw.commons.mwapi.model.ApiResponse;
+import fr.free.nrw.commons.mwapi.model.Page;
+import fr.free.nrw.commons.mwapi.model.PageCategory;
+import io.reactivex.Single;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+import okhttp3.ResponseBody;
+import timber.log.Timber;
+
+/**
+ * Uses the OkHttp library to implement calls to the Commons MediaWiki API to match GPS coordinates
+ * with nearby Commons categories. Parses the results using GSON to obtain a list of relevant
+ * categories.  Note: that caller is responsible for executing the request() method on a background
+ * thread.
+ */
+public class CategoryApi {
+
+    private final OkHttpClient okHttpClient;
+    private final HttpUrl mwUrl;
+    private final Gson gson;
+
+    @Inject
+    public CategoryApi(OkHttpClient okHttpClient, Gson gson,
+                       @Named("commons_mediawiki_url") HttpUrl mwUrl) {
+        this.okHttpClient = okHttpClient;
+        this.mwUrl = mwUrl;
+        this.gson = gson;
+    }
+
+    public Single<List<String>> request(String coords) {
+        return Single.fromCallable(() -> {
+            HttpUrl apiUrl = buildUrl(coords);
+            Timber.d("URL: %s", apiUrl.toString());
+
+            Request request = new Request.Builder().get().url(apiUrl).build();
+            Response response = okHttpClient.newCall(request).execute();
+            ResponseBody body = response.body();
+            if (body == null) {
+                return Collections.emptyList();
+            }
+
+            ApiResponse apiResponse = gson.fromJson(body.charStream(), ApiResponse.class);
+            Set<String> categories = new LinkedHashSet<>();
+            if (apiResponse != null && apiResponse.hasPages()) {
+                for (Page page : apiResponse.query.pages) {
+                    for (PageCategory category : page.getCategories()) {
+                        categories.add(category.withoutPrefix());
+                    }
+                }
+            }
+            return new ArrayList<>(categories);
+        });
+    }
+
+    /**
+     * Builds URL with image coords for MediaWiki API calls
+     * Example URL: https://commons.wikimedia.org/w/api.php?action=query&prop=categories|coordinates|pageprops&format=json&clshow=!hidden&coprop=type|name|dim|country|region|globe&codistancefrompoint=38.11386944444445|13.356263888888888&generator=geosearch&redirects=&ggscoord=38.11386944444445|1.356263888888888&ggsradius=100&ggslimit=10&ggsnamespace=6&ggsprop=type|name|dim|country|region|globe&ggsprimary=all&formatversion=2
+     *
+     * @param coords Coordinates to build query with
+     * @return URL for API query
+     */
+    private HttpUrl buildUrl(String coords) {
+        return mwUrl.newBuilder()
+                .addPathSegment("w")
+                .addPathSegment("api.php")
+                .addQueryParameter("action", "query")
+                .addQueryParameter("prop", "categories|coordinates|pageprops")
+                .addQueryParameter("format", "json")
+                .addQueryParameter("clshow", "!hidden")
+                .addQueryParameter("coprop", "type|name|dim|country|region|globe")
+                .addQueryParameter("codistancefrompoint", coords)
+                .addQueryParameter("generator", "geosearch")
+                .addQueryParameter("ggscoord", coords)
+                .addQueryParameter("ggsradius", "10000")
+                .addQueryParameter("ggslimit", "10")
+                .addQueryParameter("ggsnamespace", "6")
+                .addQueryParameter("ggsprop", "type|name|dim|country|region|globe")
+                .addQueryParameter("ggsprimary", "all")
+                .addQueryParameter("formatversion", "2")
+                .build();
+    }
+
+}
+
+
+

app/src/main/java/fr/free/nrw/commons/mwapi/model/ApiResponse.java

@@ -0,0 +1,12 @@
+package fr.free.nrw.commons.mwapi.model;
+
+public class ApiResponse {
+    public Query query;
+
+    public ApiResponse() {
+    }
+
+    public boolean hasPages() {
+        return query != null && query.pages != null;
+    }
+}

app/src/main/java/fr/free/nrw/commons/mwapi/model/Page.java

@@ -0,0 +1,17 @@
+package fr.free.nrw.commons.mwapi.model;
+
+import android.support.annotation.NonNull;
+
+public class Page {
+    public String title;
+    public PageCategory[] categories;
+    public PageCategory category;
+
+    public Page() {
+    }
+
+    @NonNull
+    public PageCategory[] getCategories() {
+        return categories != null ? categories : new PageCategory[0];
+    }
+}

app/src/main/java/fr/free/nrw/commons/mwapi/model/PageCategory.java

@@ -0,0 +1,12 @@
+package fr.free.nrw.commons.mwapi.model;
+
+public class PageCategory {
+    public String title;
+
+    public PageCategory() {
+    }
+
+    public String withoutPrefix() {
+        return title != null ? title.replace("Category:", "") : "";
+    }
+}

app/src/main/java/fr/free/nrw/commons/mwapi/model/Query.java

@@ -0,0 +1,10 @@
+package fr.free.nrw.commons.mwapi.model;
+
+public class Query {
+    public Page[] pages;
+
+    public Query() {
+        pages = new Page[0];
+    }
+
+}

app/src/main/java/fr/free/nrw/commons/upload/CategoryApi.java

@@ -1,165 +0,0 @@
-package fr.free.nrw.commons.upload;
-
-import android.support.annotation.NonNull;
-
-import com.google.gson.Gson;
-
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-
-import javax.inject.Inject;
-import javax.inject.Named;
-
-import okhttp3.Call;
-import okhttp3.Callback;
-import okhttp3.HttpUrl;
-import okhttp3.OkHttpClient;
-import okhttp3.Request;
-import okhttp3.ResponseBody;
-import timber.log.Timber;
-
-/**
- * Uses the OkHttp library to implement asynchronous calls to the Commons MediaWiki API to match
- * GPS coordinates with nearby Commons categories. Parses the results using GSON to obtain a list
- * of relevant categories.
- */
-public class CategoryApi {
-
-    private static Set<String> categorySet;
-    private static List<String> categoryList;
-    private final OkHttpClient okHttpClient;
-    private final HttpUrl mwUrl;
-    private final Gson gson;
-
-    @Inject
-    public CategoryApi(OkHttpClient okHttpClient, @Named("commons_mediawiki_url") HttpUrl mwUrl, Gson gson) {
-        this.okHttpClient = okHttpClient;
-        this.mwUrl = mwUrl;
-        this.gson = gson;
-        categorySet = new HashSet<>();
-    }
-
-    public static List<String> getGpsCat() {
-        return categoryList;
-    }
-
-    public static void setGpsCat(List<String> cachedList) {
-        categoryList = new ArrayList<>();
-        categoryList.addAll(cachedList);
-        Timber.d("Setting GPS cats from cache: %s", categoryList);
-    }
-
-    public void request(String coords) {
-        String apiUrl = buildUrl(coords);
-        Timber.d("URL: %s", apiUrl);
-
-        Call call = okHttpClient.newCall(new Request.Builder().get().url(apiUrl).build());
-        call.enqueue(new Callback() {
-            @Override
-            public void onFailure(@NonNull Call call, @NonNull IOException e) {
-                Timber.e(e);
-                GpsCatExists.setGpsCatExists(false);
-            }
-
-            @Override
-            public void onResponse(@NonNull Call call, @NonNull okhttp3.Response response) {
-                categoryList = new ArrayList<>();
-                categorySet = new HashSet<>();
-                ResponseBody body = response.body();
-                if (body == null) {
-                    return;
-                }
-                QueryResponse queryResponse = gson.fromJson(body.charStream(), QueryResponse.class);
-                if (queryResponse != null && queryResponse.query != null && queryResponse.query.pages != null) {
-                    for (Page page : queryResponse.query.pages) {
-                        if (page.categories != null) {
-                            for (Category category : page.categories) {
-                                String categoryString = category.title.replace("Category:", "");
-                                categorySet.add(categoryString);
-                            }
-                            categoryList = new ArrayList<>(categorySet);
-                        }
-                    }
-                }
-                GpsCatExists.setGpsCatExists(!categorySet.isEmpty());
-            }
-        });
-    }
-
-    /**
-     * Builds URL with image coords for MediaWiki API calls
-     * Example URL: https://commons.wikimedia.org/w/api.php?action=query&prop=categories|coordinates|pageprops&format=json&clshow=!hidden&coprop=type|name|dim|country|region|globe&codistancefrompoint=38.11386944444445|13.356263888888888&generator=geosearch&redirects=&ggscoord=38.11386944444445|1.356263888888888&ggsradius=100&ggslimit=10&ggsnamespace=6&ggsprop=type|name|dim|country|region|globe&ggsprimary=all&formatversion=2
-     *
-     * @param coords Coordinates to build query with
-     * @return URL for API query
-     */
-    private String buildUrl(String coords) {
-        return mwUrl.newBuilder()
-                .addPathSegment("w")
-                .addPathSegment("api.php")
-                .addQueryParameter("action", "query")
-                .addQueryParameter("prop", "categories|coordinates|pageprops")
-                .addQueryParameter("format", "json")
-                .addQueryParameter("clshow", "!hidden")
-                .addQueryParameter("coprop", "type|name|dim|country|region|globe")
-                .addQueryParameter("codistancefrompoint", coords)
-                .addQueryParameter("generator", "geosearch")
-                .addQueryParameter("ggscoord", coords)
-                .addQueryParameter("ggsradius", "10000")
-                .addQueryParameter("ggslimit", "10")
-                .addQueryParameter("ggsnamespace", "6")
-                .addQueryParameter("ggsprop", "type|name|dim|country|region|globe")
-                .addQueryParameter("ggsprimary", "all")
-                .addQueryParameter("formatversion", "2")
-                .build().toString();
-    }
-
-    public static class GpsCatExists {
-        private static boolean gpsCatExists;
-
-        public static void setGpsCatExists(boolean gpsCat) {
-            gpsCatExists = gpsCat;
-        }
-
-        public static boolean getGpsCatExists() {
-            return gpsCatExists;
-        }
-    }
-
-    private static class QueryResponse {
-        public Query query;
-
-        public QueryResponse() {
-        }
-    }
-
-    private static class Query {
-        public Page[] pages;
-
-        public Query() {
-            pages = new Page[0];
-        }
-    }
-
-    private static class Page {
-        public String title;
-        public Category[] categories;
-        public Category category;
-
-        public Page() {
-        }
-    }
-
-    private static class Category {
-        public String title;
-
-        public Category() {
-        }
-    }
-}
-
-
-

app/src/main/java/fr/free/nrw/commons/upload/GpsCategoryModel.java

@@ -0,0 +1,40 @@
+package fr.free.nrw.commons.upload;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+@Singleton
+public class GpsCategoryModel {
+    private Set<String> categorySet;
+
+    @Inject
+    public GpsCategoryModel() {
+        clear();
+    }
+
+    public void clear() {
+        categorySet = new HashSet<>();
+    }
+
+    public boolean getGpsCatExists() {
+        return !categorySet.isEmpty();
+    }
+
+    public List<String> getCategoryList() {
+        return new ArrayList<>(categorySet);
+    }
+
+    public void setCategoryList(List<String> categoryList) {
+        clear();
+        categorySet.addAll(categoryList != null ? categoryList : new ArrayList<>());
+    }
+
+    public void add(String categoryString) {
+        categorySet.add(categoryString);
+    }
+}

app/src/main/java/fr/free/nrw/commons/upload/ShareActivity.java

@@ -1,6 +1,7 @@
 package fr.free.nrw.commons.upload;
 
 import android.Manifest;
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
@@ -73,8 +74,10 @@ import fr.free.nrw.commons.modifications.ModificationsContentProvider;
 import fr.free.nrw.commons.modifications.ModifierSequence;
 import fr.free.nrw.commons.modifications.ModifierSequenceDao;
 import fr.free.nrw.commons.modifications.TemplateRemoveModifier;
+import fr.free.nrw.commons.mwapi.CategoryApi;
 
 import fr.free.nrw.commons.mwapi.MediaWikiApi;
+import io.reactivex.schedulers.Schedulers;
 import fr.free.nrw.commons.utils.ViewUtil;
 import timber.log.Timber;
 
@@ -127,6 +130,8 @@ public class ShareActivity
     @Inject
     @Named("default_preferences")
     SharedPreferences prefs;
+    @Inject
+    GpsCategoryModel gpsCategoryModel;
 
     private String source;
     private String mimeType;
@@ -687,8 +692,9 @@ public class ShareActivity
 
     /**
      * Initiates retrieval of image coordinates or user coordinates, and caching of coordinates.
-     * Then initiates the calls to MediaWiki API through an instance of MwVolleyApi.
+     * Then initiates the calls to MediaWiki API through an instance of CategpryApi.
      */
+    @SuppressLint("CheckResult")
     public void useImageCoords() {
         if (decimalCoords != null) {
             Timber.d("Decimal coords of image: %s", decimalCoords);
@@ -707,12 +713,21 @@ public class ShareActivity
             // If no categories found in cache, call MediaWiki API to match image coords with nearby Commons categories
             if (catListEmpty) {
                 cacheFound = false;
-                apiCall.request(decimalCoords);
+                apiCall.request(decimalCoords)
+                        .subscribeOn(Schedulers.io())
+                        .observeOn(Schedulers.io())
+                        .subscribe(
+                                gpsCategoryModel::setCategoryList,
+                                throwable -> {
+                                    Timber.e(throwable);
+                                    gpsCategoryModel.clear();
+                                }
+                        );
                 Timber.d("displayCatList size 0, calling MWAPI %s", displayCatList);
             } else {
                 cacheFound = true;
-                Timber.d("Cache found, setting categoryList in MwVolleyApi to %s", displayCatList);
+                Timber.d("Cache found, setting categoryList in model to %s", displayCatList);
-                CategoryApi.setGpsCat(displayCatList);
+                gpsCategoryModel.setCategoryList(displayCatList);
             }
         }else{
             Timber.d("EXIF: no coords");

app/src/test/kotlin/fr/free/nrw/commons/TestCommonsApplication.kt

@@ -8,7 +8,6 @@ import com.nhaarman.mockito_kotlin.mock
 import com.squareup.leakcanary.RefWatcher
 import fr.free.nrw.commons.auth.AccountUtil
 import fr.free.nrw.commons.auth.SessionManager
-import fr.free.nrw.commons.caching.CacheController
 import fr.free.nrw.commons.data.DBOpenHelper
 import fr.free.nrw.commons.di.CommonsApplicationComponent
 import fr.free.nrw.commons.di.CommonsApplicationModule
@@ -42,7 +41,6 @@ class MockCommonsApplicationModule(appContext: Context) : CommonsApplicationModu
     val uploadController: UploadController = mock()
     val mockSessionManager: SessionManager = mock()
     val locationServiceManager: LocationServiceManager = mock()
-    val cacheController: CacheController = mock()
     val mockDbOpenHelper: DBOpenHelper = mock()
     val nearbyPlaces: NearbyPlaces = mock()
     val lruCache: LruCache<String, String> = mock()
@@ -73,8 +71,6 @@ class MockCommonsApplicationModule(appContext: Context) : CommonsApplicationModu
 
     override fun provideLocationServiceManager(context: Context): LocationServiceManager = locationServiceManager
 
-    override fun provideCacheController(): CacheController = cacheController
-
     override fun provideDBOpenHelper(context: Context): DBOpenHelper = mockDbOpenHelper
 
     override fun provideNearbyPlaces(): NearbyPlaces = nearbyPlaces

app/src/test/kotlin/fr/free/nrw/commons/mwapi/CategoryApiTest.kt

@@ -0,0 +1,178 @@
+package fr.free.nrw.commons.mwapi
+
+import com.google.gson.Gson
+import fr.free.nrw.commons.mwapi.model.Page
+import fr.free.nrw.commons.mwapi.model.PageCategory
+import okhttp3.HttpUrl
+import okhttp3.OkHttpClient
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+
+class CategoryApiTest {
+    private lateinit var server: MockWebServer
+    private lateinit var url: String
+    private lateinit var categoryApi: CategoryApi
+
+    @Before
+    fun setUp() {
+        server = MockWebServer()
+        url = "http://${server.hostName}:${server.port}/"
+        categoryApi = CategoryApi(OkHttpClient.Builder().build(), Gson(), HttpUrl.parse(url))
+    }
+
+    @After
+    fun teardown() {
+        server.shutdown()
+    }
+
+    @Test
+    fun apiReturnsEmptyListWhenError() {
+        server.enqueue(MockResponse().setResponseCode(400).setBody(""))
+
+        assertTrue(categoryApi.request("foo").blockingGet().isEmpty())
+    }
+
+    @Test
+    fun apiReturnsEmptyWhenTheresNoQuery() {
+        server.success(emptyMap())
+
+        assertTrue(categoryApi.request("foo").blockingGet().isEmpty())
+    }
+
+    @Test
+    fun apiReturnsEmptyWhenQueryHasNoPages() {
+        server.success(mapOf("query" to emptyMap<String, Any>()))
+
+        assertTrue(categoryApi.request("foo").blockingGet().isEmpty())
+    }
+
+    @Test
+    fun apiReturnsEmptyWhenQueryHasPagesButTheyreEmpty() {
+        server.success(mapOf("query" to
+                mapOf("pages" to emptyList<String>())))
+
+        assertTrue(categoryApi.request("foo").blockingGet().isEmpty())
+    }
+
+    @Test
+    fun singlePageSingleCategory() {
+        server.success(mapOf("query" to
+                mapOf("pages" to listOf(
+                        page(listOf("one"))
+                ))))
+
+        val response = categoryApi.request("foo").blockingGet()
+
+        assertEquals(1, response.size)
+        assertEquals("one", response[0])
+    }
+
+    @Test
+    fun multiplePagesSingleCategory() {
+        server.success(mapOf("query" to
+                mapOf("pages" to listOf(
+                        page(listOf("one")),
+                        page(listOf("two"))
+                ))))
+
+        val response = categoryApi.request("foo").blockingGet()
+
+        assertEquals(2, response.size)
+        assertEquals("one", response[0])
+        assertEquals("two", response[1])
+    }
+
+    @Test
+    fun singlePageMultipleCategories() {
+        server.success(mapOf("query" to
+                mapOf("pages" to listOf(
+                        page(listOf("one", "two"))
+                ))))
+
+        val response = categoryApi.request("foo").blockingGet()
+
+        assertEquals(2, response.size)
+        assertEquals("one", response[0])
+        assertEquals("two", response[1])
+    }
+
+    @Test
+    fun multiplePagesMultipleCategories() {
+        server.success(mapOf("query" to
+                mapOf("pages" to listOf(
+                        page(listOf("one", "two")),
+                        page(listOf("three", "four"))
+                ))))
+
+        val response = categoryApi.request("foo").blockingGet()
+
+        assertEquals(4, response.size)
+        assertEquals("one", response[0])
+        assertEquals("two", response[1])
+        assertEquals("three", response[2])
+        assertEquals("four", response[3])
+    }
+
+    @Test
+    fun multiplePagesMultipleCategories_duplicatesRemoved() {
+        server.success(mapOf("query" to
+                mapOf("pages" to listOf(
+                        page(listOf("one", "two", "three")),
+                        page(listOf("three", "four", "one"))
+                ))))
+
+        val response = categoryApi.request("foo").blockingGet()
+
+        assertEquals(4, response.size)
+        assertEquals("one", response[0])
+        assertEquals("two", response[1])
+        assertEquals("three", response[2])
+        assertEquals("four", response[3])
+    }
+
+    @Test
+    fun requestSendsWhatWeExpect() {
+        server.success(mapOf("query" to mapOf("pages" to emptyList<String>())))
+
+        val coords = "foo,bar"
+        categoryApi.request(coords).blockingGet()
+
+        server.takeRequest().let { request ->
+            assertEquals("GET", request.method)
+            assertEquals("/w/api.php", request.requestUrl.encodedPath())
+            request.requestUrl.let { url ->
+                assertEquals("query", url.queryParameter("action"))
+                assertEquals("categories|coordinates|pageprops", url.queryParameter("prop"))
+                assertEquals("json", url.queryParameter("format"))
+                assertEquals("!hidden", url.queryParameter("clshow"))
+                assertEquals("type|name|dim|country|region|globe", url.queryParameter("coprop"))
+                assertEquals(coords, url.queryParameter("codistancefrompoint"))
+                assertEquals("geosearch", url.queryParameter("generator"))
+                assertEquals(coords, url.queryParameter("ggscoord"))
+                assertEquals("10000", url.queryParameter("ggsradius"))
+                assertEquals("10", url.queryParameter("ggslimit"))
+                assertEquals("6", url.queryParameter("ggsnamespace"))
+                assertEquals("type|name|dim|country|region|globe", url.queryParameter("ggsprop"))
+                assertEquals("all", url.queryParameter("ggsprimary"))
+                assertEquals("2", url.queryParameter("formatversion"))
+            }
+        }
+    }
+
+    private fun page(catList: List<String>) = Page().apply {
+        categories = catList.map {
+            PageCategory().apply {
+                title = "Category:$it"
+            }
+        }.toTypedArray()
+    }
+}
+
+fun MockWebServer.success(response: Map<String, Any>) {
+    enqueue(MockResponse().setResponseCode(200).setBody(Gson().toJson(response)))
+}

app/src/test/kotlin/fr/free/nrw/commons/mwapi/model/ApiResponseTest.kt

@@ -0,0 +1,28 @@
+package fr.free.nrw.commons.mwapi.model
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class ApiResponseTest {
+    @Test
+    fun hasPages_whenQueryIsNull() {
+        val response = ApiResponse()
+        assertFalse(response.hasPages())
+    }
+
+    @Test
+    fun hasPages_whenPagesIsNull() {
+        val response = ApiResponse()
+        response.query = Query()
+        response.query.pages = null
+        assertFalse(response.hasPages())
+    }
+
+    @Test
+    fun hasPages_defaultsToSafeValue() {
+        val response = ApiResponse()
+        response.query = Query()
+        assertNotNull(response.query.pages)
+        assertTrue(response.hasPages())
+    }
+}

app/src/test/kotlin/fr/free/nrw/commons/mwapi/model/PageCategoryTest.kt

@@ -0,0 +1,20 @@
+package fr.free.nrw.commons.mwapi.model
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class PageCategoryTest {
+    @Test
+    fun stripPrefix_whenPresent() {
+        val testObject = PageCategory()
+        testObject.title = "Category:Foo"
+        assertEquals("Foo", testObject.withoutPrefix())
+    }
+
+    @Test
+    fun stripPrefix_prefixAbsent() {
+        val testObject = PageCategory()
+        testObject.title = "Foo_Bar"
+        assertEquals("Foo_Bar", testObject.withoutPrefix())
+    }
+}

app/src/test/kotlin/fr/free/nrw/commons/mwapi/model/PageTest.kt

@@ -0,0 +1,12 @@
+package fr.free.nrw.commons.mwapi.model
+
+import org.junit.Assert.assertNotNull
+import org.junit.Test
+
+class PageTest {
+    @Test
+    fun categoriesDefaultToSafeValue() {
+        val page = Page()
+        assertNotNull(page.getCategories())
+    }
+}

app/src/test/kotlin/fr/free/nrw/commons/upload/GpsCategoryModelTest.kt

@@ -0,0 +1,77 @@
+package fr.free.nrw.commons.upload
+
+import org.junit.Assert.*
+import org.junit.Before
+import org.junit.Test
+
+class GpsCategoryModelTest {
+
+    private lateinit var testObject : GpsCategoryModel
+
+    @Before
+    fun setUp() {
+        testObject = GpsCategoryModel()
+    }
+
+    @Test
+    fun initiallyTheModelIsEmpty() {
+        assertFalse(testObject.gpsCatExists)
+        assertTrue(testObject.categoryList.isEmpty())
+    }
+
+    @Test
+    fun addingCategoriesToTheModel() {
+        testObject.add("one")
+        assertTrue(testObject.gpsCatExists)
+        assertFalse(testObject.categoryList.isEmpty())
+        assertEquals(listOf("one"), testObject.categoryList)
+    }
+
+    @Test
+    fun duplicatesAreIgnored() {
+        testObject.add("one")
+        testObject.add("one")
+        assertEquals(listOf("one"), testObject.categoryList)
+    }
+
+    @Test
+    fun modelProtectsAgainstExternalModification() {
+        testObject.add("one")
+
+        val list = testObject.categoryList
+        list.add("two")
+
+        assertEquals(listOf("one"), testObject.categoryList)
+    }
+
+    @Test
+    fun clearingTheModel() {
+        testObject.add("one")
+
+        testObject.clear()
+        assertFalse(testObject.gpsCatExists)
+        assertTrue(testObject.categoryList.isEmpty())
+
+        testObject.add("two")
+        assertEquals(listOf("two"), testObject.categoryList)
+    }
+
+    @Test
+    fun settingTheListHandlesNull() {
+        testObject.add("one")
+
+        testObject.categoryList = null
+
+        assertFalse(testObject.gpsCatExists)
+        assertTrue(testObject.categoryList.isEmpty())
+    }
+
+    @Test
+    fun setttingTheListOverwritesExistingValues() {
+        testObject.add("one")
+
+        testObject.categoryList = listOf("two")
+
+        assertEquals(listOf("two"), testObject.categoryList)
+    }
+}