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.when;
19 import static org.mockito.Mockito.withSettings;
20 
21 import android.content.Context;
22 import android.content.res.Configuration;
23 import android.content.res.Resources;
24 import android.util.Log;
25 import android.util.SparseArray;
26 
27 import org.mockito.invocation.InvocationOnMock;
28 
29 /**
30  * Provides a version of Resources that defaults to all existing resources, but can have ids
31  * changed to return specific values.
32  * <p>
33  * TestableResources are lazily initialized, be sure to call
34  * {@link TestableContext#ensureTestableResources} before your tested code has an opportunity
35  * to cache {@link Context#getResources}.
36  * </p>
37  */
38 public class TestableResources {
39 
40     private static final String TAG = "TestableResources";
41     private final Resources mResources;
42     private final SparseArray<Object> mOverrides = new SparseArray<>();
43 
44     /** Creates a TestableResources instance that calls through to the given real Resources. */
TestableResources(Resources realResources)45     public TestableResources(Resources realResources) {
46         mResources = mock(Resources.class, withSettings()
47                 .spiedInstance(realResources)
48                 .defaultAnswer(this::answer));
49     }
50 
51     /**
52      * Gets the implementation of Resources that will return overridden values when called.
53      */
getResources()54     public Resources getResources() {
55         return mResources;
56     }
57 
58     /**
59      * Sets a configuration for {@link #getResources()} to return to allow custom configs to
60      * be set and tested.
61      *
62      * @param configuration the configuration to return from resources.
63      */
overrideConfiguration(Configuration configuration)64     public void overrideConfiguration(Configuration configuration) {
65         when(mResources.getConfiguration()).thenReturn(configuration);
66     }
67 
68     /**
69      * Sets the return value for the specified resource id.
70      * <p>
71      * Since resource ids are unique there is a single addOverride that will override the value
72      * whenever it is gotten regardless of which method is used (i.e. getColor or getDrawable).
73      * </p>
74      *
75      * @param id    The resource id to be overridden
76      * @param value The value of the resource, null to cause a {@link Resources.NotFoundException}
77      *              when gotten.
78      */
addOverride(int id, Object value)79     public void addOverride(int id, Object value) {
80         mOverrides.put(id, value);
81     }
82 
83     /**
84      * Removes the override for the specified id.
85      * <p>
86      * This should be called over addOverride(id, null), because specifying a null value will
87      * cause a {@link Resources.NotFoundException} whereas removing the override will actually
88      * switch back to returning the default/real value of the resource.
89      * </p>
90      */
removeOverride(int id)91     public void removeOverride(int id) {
92         mOverrides.remove(id);
93     }
94 
answer(InvocationOnMock invocationOnMock)95     private Object answer(InvocationOnMock invocationOnMock) throws Throwable {
96         // Only try to override methods with an integer first argument
97         if (invocationOnMock.getArguments().length > 0) {
98             Object argument = invocationOnMock.getArgument(0);
99             if (argument instanceof Integer) {
100                 try {
101                     int id = (Integer)argument;
102                     int index = mOverrides.indexOfKey(id);
103                     if (index >= 0) {
104                         Object value = mOverrides.valueAt(index);
105                         if (value == null) throw new Resources.NotFoundException();
106                         return value;
107                     }
108                 } catch (Resources.NotFoundException e) {
109                     // Let through NotFoundException.
110                     throw e;
111                 } catch (Throwable t) {
112                     // Generic catching for the many things that can go wrong, fall back to
113                     // the real implementation.
114                     Log.i(TAG, "Falling back to default resources call " + t);
115                 }
116             }
117         }
118         return invocationOnMock.callRealMethod();
119     }
120 }
121