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. */
TestableResources(Resources realResources)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      */
getResources()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      */
addOverride(int id, Object value)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      */
removeOverride(int id)79     public void removeOverride(int id) {
80         mOverrides.remove(id);
81     }
82 
answer(InvocationOnMock invocationOnMock)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