PagedStorageDiffHelperTest.kt revision bdc4c86d3dff74f6634a38e2f7b316b0e823a2c8 
1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package androidx.paging
18
19import android.support.test.filters.SmallTest
20import androidx.recyclerview.widget.DiffUtil
21import androidx.recyclerview.widget.ListUpdateCallback
22import org.junit.Assert.assertEquals
23import org.junit.Test
24import org.junit.runner.RunWith
25import org.junit.runners.JUnit4
26import org.mockito.Mockito.mock
27import org.mockito.Mockito.verify
28import org.mockito.Mockito.verifyNoMoreInteractions
29import org.mockito.Mockito.verifyZeroInteractions
30
31@SmallTest
32@RunWith(JUnit4::class)
33class PagedStorageDiffHelperTest {
34
35    @Test
36    fun sameListNoUpdates() {
37        validateTwoListDiff(
38                PagedStorage(5, listOf("a", "b", "c"), 5),
39                PagedStorage(5, listOf("a", "b", "c"), 5)) {
40            verifyZeroInteractions(it)
41        }
42    }
43
44    @Test
45    fun sameListNoUpdatesPlaceholder() {
46        val storageNoPlaceholder = PagedStorage(0, listOf("a", "b", "c"), 10)
47
48        val storageWithPlaceholder = PagedStorage(0, listOf("a", "b", "c"), 10)
49        storageWithPlaceholder.allocatePlaceholders(3, 0, 3,
50                /* ignored */ mock(PagedStorage.Callback::class.java))
51
52        // even though one has placeholders, and null counts are different...
53        assertEquals(10, storageNoPlaceholder.trailingNullCount)
54        assertEquals(7, storageWithPlaceholder.trailingNullCount)
55
56        // ... should be no interactions, since content still same
57        validateTwoListDiff(
58                storageNoPlaceholder,
59                storageWithPlaceholder) {
60            verifyZeroInteractions(it)
61        }
62    }
63
64    @Test
65    fun appendFill() {
66        validateTwoListDiff(
67                PagedStorage(5, listOf("a", "b"), 5),
68                PagedStorage(5, listOf("a", "b", "c"), 4)) {
69            verify(it).onRemoved(11, 1)
70            verify(it).onInserted(7, 1)
71            // NOTE: ideally would be onChanged(7, 1, null)
72            verifyNoMoreInteractions(it)
73        }
74    }
75
76    @Test
77    fun prependFill() {
78        validateTwoListDiff(
79                PagedStorage(5, listOf("b", "c"), 5),
80                PagedStorage(4, listOf("a", "b", "c"), 5)) {
81            verify(it).onRemoved(0, 1)
82            verify(it).onInserted(4, 1)
83            //NOTE: ideally would be onChanged(4, 1, null);
84            verifyNoMoreInteractions(it)
85        }
86    }
87
88    @Test
89    fun change() {
90        validateTwoListDiff(
91                PagedStorage(5, listOf("a1", "b1", "c1"), 5),
92                PagedStorage(5, listOf("a2", "b1", "c2"), 5)) {
93            verify(it).onChanged(5, 1, null)
94            verify(it).onChanged(7, 1, null)
95            verifyNoMoreInteractions(it)
96        }
97    }
98
99    companion object {
100        private val DIFF_CALLBACK = object : DiffUtil.ItemCallback<String>() {
101            override fun areItemsTheSame(oldItem: String, newItem: String): Boolean {
102                // first char means same item
103                return oldItem[0] == newItem[0]
104            }
105
106            override fun areContentsTheSame(oldItem: String, newItem: String): Boolean {
107                return oldItem == newItem
108            }
109        }
110
111        private fun validateTwoListDiff(oldList: PagedStorage<String>,
112                                        newList: PagedStorage<String>,
113                                        validator: (callback: ListUpdateCallback) -> Unit) {
114            val diffResult = PagedStorageDiffHelper.computeDiff(oldList, newList, DIFF_CALLBACK)
115
116            val listUpdateCallback = mock(ListUpdateCallback::class.java)
117            PagedStorageDiffHelper.dispatchDiff(listUpdateCallback, oldList, newList, diffResult)
118
119            validator(listUpdateCallback)
120        }
121    }
122}
123