1 files changed, 128 insertions, 0 deletions
diff --git a/android/arch/paging/ContiguousDiffHelperTest.java b/android/arch/paging/ContiguousDiffHelperTest.java
new file mode 100644
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+++ b/android/arch/paging/ContiguousDiffHelperTest.java
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+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.arch.paging;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+import android.support.annotation.NonNull;
+import android.support.test.filters.SmallTest;
+import android.support.v7.recyclerview.extensions.DiffCallback;
+import android.support.v7.util.DiffUtil;
+import android.support.v7.util.ListUpdateCallback;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.Mockito;
+
+@SmallTest
+@RunWith(JUnit4.class)
+public class ContiguousDiffHelperTest {
+    private interface CallbackValidator {
+        void validate(ListUpdateCallback callback);
+    }
+
+    private static final DiffCallback<String> DIFF_CALLBACK = new DiffCallback<String>() {
+        @Override
+        public boolean areItemsTheSame(@NonNull String oldItem, @NonNull String newItem) {
+            // first char means same item
+            return oldItem.charAt(0) == newItem.charAt(0);
+        }
+
+        @Override
+        public boolean areContentsTheSame(@NonNull String oldItem, @NonNull String newItem) {
+            return oldItem.equals(newItem);
+        }
+    };
+
+    private void validateTwoListDiff(StringPagedList oldList, StringPagedList newList,
+            CallbackValidator callbackValidator) {
+        DiffUtil.DiffResult diffResult = ContiguousDiffHelper.computeDiff(oldList, newList,
+                DIFF_CALLBACK, false);
+
+        ListUpdateCallback listUpdateCallback = Mockito.mock(ListUpdateCallback.class);
+        ContiguousDiffHelper.dispatchDiff(listUpdateCallback, oldList, newList, diffResult);
+
+        callbackValidator.validate(listUpdateCallback);
+    }
+
+    @Test
+    public void sameListNoUpdates() {
+        validateTwoListDiff(
+                new StringPagedList(5, 5, "a", "b", "c"),
+                new StringPagedList(5, 5, "a", "b", "c"),
+                new CallbackValidator() {
+                    @Override
+                    public void validate(ListUpdateCallback callback) {
+                        verifyZeroInteractions(callback);
+                    }
+                }
+        );
+    }
+
+    @Test
+    public void appendFill() {
+        validateTwoListDiff(
+                new StringPagedList(5, 5, "a", "b"),
+                new StringPagedList(5, 4, "a", "b", "c"),
+                new CallbackValidator() {
+                    @Override
+                    public void validate(ListUpdateCallback callback) {
+                        verify(callback).onRemoved(11, 1);
+                        verify(callback).onInserted(7, 1);
+                        // NOTE: ideally would be onChanged(7, 1, null)
+                        verifyNoMoreInteractions(callback);
+                    }
+                }
+        );
+    }
+
+    @Test
+    public void prependFill() {
+        validateTwoListDiff(
+                new StringPagedList(5, 5, "b", "c"),
+                new StringPagedList(4, 5, "a", "b", "c"),
+                new CallbackValidator() {
+                    @Override
+                    public void validate(ListUpdateCallback callback) {
+                        verify(callback).onRemoved(0, 1);
+                        verify(callback).onInserted(4, 1);
+                        //NOTE: ideally would be onChanged(4, 1, null);
+                        verifyNoMoreInteractions(callback);
+                    }
+                }
+        );
+    }
+
+    @Test
+    public void change() {
+        validateTwoListDiff(
+                new StringPagedList(5, 5, "a1", "b1", "c1"),
+                new StringPagedList(5, 5, "a2", "b1", "c2"),
+                new CallbackValidator() {
+                    @Override
+                    public void validate(ListUpdateCallback callback) {
+                        verify(callback).onChanged(5, 1, null);
+                        verify(callback).onChanged(7, 1, null);
+                        verifyNoMoreInteractions(callback);
+                    }
+                }
+        );
+    }
+}