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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
      5  * except in compliance with the License. You may obtain a copy of the License at
      6  *
      7  *      http://www.apache.org/licenses/LICENSE-2.0
      8  *
      9  * Unless required by applicable law or agreed to in writing, software distributed under the
     10  * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     11  * KIND, either express or implied. See the License for the specific language governing
     12  * permissions and limitations under the License.
     13  */
     14 
     15 package android.testing;
     16 
     17 import static org.mockito.Mockito.mock;
     18 import static org.mockito.Mockito.withSettings;
     19 
     20 import android.content.Context;
     21 import android.content.res.Resources;
     22 import android.util.Log;
     23 import android.util.SparseArray;
     24 
     25 import org.mockito.invocation.InvocationOnMock;
     26 
     27 /**
     28  * Provides a version of Resources that defaults to all existing resources, but can have ids
     29  * changed to return specific values.
     30  * <p>
     31  * TestableResources are lazily initialized, be sure to call
     32  * {@link TestableContext#ensureTestableResources} before your tested code has an opportunity
     33  * to cache {@link Context#getResources}.
     34  * </p>
     35  */
     36 public class TestableResources {
     37 
     38     private static final String TAG = "TestableResources";
     39     private final Resources mResources;
     40     private final SparseArray<Object> mOverrides = new SparseArray<>();
     41 
     42     /** Creates a TestableResources instance that calls through to the given real Resources. */
     43     public TestableResources(Resources realResources) {
     44         mResources = mock(Resources.class, withSettings()
     45                 .spiedInstance(realResources)
     46                 .defaultAnswer(this::answer));
     47     }
     48 
     49     /**
     50      * Gets the implementation of Resources that will return overridden values when called.
     51      */
     52     public Resources getResources() {
     53         return mResources;
     54     }
     55 
     56     /**
     57      * Sets the return value for the specified resource id.
     58      * <p>
     59      * Since resource ids are unique there is a single addOverride that will override the value
     60      * whenever it is gotten regardless of which method is used (i.e. getColor or getDrawable).
     61      * </p>
     62      * @param id The resource id to be overridden
     63      * @param value The value of the resource, null to cause a {@link Resources.NotFoundException}
     64      *              when gotten.
     65      */
     66     public void addOverride(int id, Object value) {
     67         mOverrides.put(id, value);
     68     }
     69 
     70     /**
     71      * Removes the override for the specified id.
     72      * <p>
     73      * This should be called over addOverride(id, null), because specifying a null value will
     74      * cause a {@link Resources.NotFoundException} whereas removing the override will actually
     75      * switch back to returning the default/real value of the resource.
     76      * </p>
     77      * @param id
     78      */
     79     public void removeOverride(int id) {
     80         mOverrides.remove(id);
     81     }
     82 
     83     private Object answer(InvocationOnMock invocationOnMock) throws Throwable {
     84         try {
     85             int id = invocationOnMock.getArgument(0);
     86             int index = mOverrides.indexOfKey(id);
     87             if (index >= 0) {
     88                 Object value = mOverrides.valueAt(index);
     89                 if (value == null) throw new Resources.NotFoundException();
     90                 return value;
     91             }
     92         } catch (Resources.NotFoundException e) {
     93             // Let through NotFoundException.
     94             throw e;
     95         } catch (Throwable t) {
     96             // Generic catching for the many things that can go wrong, fall back to
     97             // the real implementation.
     98             Log.i(TAG, "Falling back to default resources call " + t);
     99         }
    100         return invocationOnMock.callRealMethod();
    101     }
    102 }
    103