[Suggestions] Remove TreeNode.getSuggestionAt() in favor of a visitor.

chrome/android/junit/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSectionTest.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.collection.IsIterableContainingInOrder.contains;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ skipping 25 matching lines @@
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.annotation.Config;
 
 import org.chromium.base.Callback;
 import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.base.test.util.Feature;
 import org.chromium.chrome.browser.DisableHistogramsRule;
 import org.chromium.chrome.browser.ntp.cards.NewTabPageViewHolder.UpdateLayoutParamsCallback;
+import org.chromium.chrome.browser.ntp.cards.SuggestionsSection.SuggestionsList;
 import org.chromium.chrome.browser.ntp.snippets.CategoryStatus;
 import org.chromium.chrome.browser.ntp.snippets.SnippetArticle;
 import org.chromium.chrome.browser.ntp.snippets.SuggestionsSource;
 import org.chromium.chrome.browser.offlinepages.OfflinePageItem;
 import org.chromium.chrome.browser.suggestions.ContentSuggestionsAdditionalAction;
 import org.chromium.chrome.browser.suggestions.SuggestionsEventReporter;
 import org.chromium.chrome.browser.suggestions.SuggestionsNavigationDelegate;
 import org.chromium.chrome.browser.suggestions.SuggestionsRanker;
 import org.chromium.chrome.browser.suggestions.SuggestionsUiDelegate;
 import org.chromium.chrome.test.util.browser.suggestions.ContentSuggestionsTestUtils.CategoryInfoBuilder;
@@ skipping 422 matching lines @@
         // Indices in section are off-by-one (index 0 is the header).
         bindViewHolders(section, 1, 2);
 
         List<SnippetArticle> newSnippets =
                 createDummySuggestions(3, TEST_CATEGORY_ID, "new");
         // Copy the list when passing to the section - it may alter it but we later need it.
         section.updateSuggestions(createSourceFor(new ArrayList<>(newSnippets)));
         verify(mParent).onItemRangeRemoved(section, 2, 3);
         verify(mParent).onItemRangeInserted(section, 2, 2);
         assertEquals(3, section.getSuggestionsCount());
-        assertEquals(snippets.get(0), section.getSuggestionAt(1));
-        assertNotEquals(snippets.get(1), section.getSuggestionAt(2));
-        assertEquals(newSnippets.get(0), section.getSuggestionAt(2));
-        assertNotEquals(snippets.get(2), section.getSuggestionAt(3));
-        assertEquals(newSnippets.get(1), section.getSuggestionAt(3));
+        SuggestionsList suggestionList = section.getSuggestionListForTesting();
+        assertEquals(snippets.get(0), suggestionList.getSuggestionAt(0));
+        assertNotEquals(snippets.get(1), suggestionList.getSuggestionAt(1));
+        assertEquals(newSnippets.get(0), suggestionList.getSuggestionAt(1));
+        assertNotEquals(snippets.get(2), suggestionList.getSuggestionAt(2));
+        assertEquals(newSnippets.get(1), suggestionList.getSuggestionAt(2));
 
         assertTrue(section.isDataStale());
     }
 
     /**
      * Tests that the UI does not update the first two items of the section if they have been
      * viewed.
      */
     @Test
     @Feature({"Ntp"})
     public void testUpdateSectionDoesNotReplaceFirstTwoSuggestionWhenSeen() {
         List<SnippetArticle> snippets = createDummySuggestions(4, TEST_CATEGORY_ID, "old");
         // Copy the list when passing to the section - it may alter it but we later need it.
         SuggestionsSection section =
                 createSectionWithSuggestions(new ArrayList<>(snippets));
         assertEquals(4, section.getSuggestionsCount());
 
         // Bind the first two suggestions - indicate that they are being viewed.
         // Indices in section are off-by-one (index 0 is the header).
         bindViewHolders(section, 1, 3);
 
         List<SnippetArticle> newSnippets =
                 createDummySuggestions(3, TEST_CATEGORY_ID, "new");
         // Copy the list when passing to the section - it may alter it but we later need it.
         section.updateSuggestions(createSourceFor(new ArrayList<>(newSnippets)));
         verify(mParent).onItemRangeRemoved(section, 3, 2);
         verify(mParent).onItemRangeInserted(section, 3, 1);
         assertEquals(3, section.getSuggestionsCount());
-        assertEquals(snippets.get(0), section.getSuggestionAt(1));
-        assertEquals(snippets.get(1), section.getSuggestionAt(2));
-        assertNotEquals(snippets.get(2), section.getSuggestionAt(3));
-        assertEquals(newSnippets.get(0), section.getSuggestionAt(3));
+        SuggestionsList suggestionList = section.getSuggestionListForTesting();

[dgn, 2017/05/24 11:30:31]

isn't it possible to use visitor to check that?

[Bernhard Bauer, 2017/05/25 12:27:54]

Sure, done.

+        assertEquals(snippets.get(0), suggestionList.getSuggestionAt(0));
+        assertEquals(snippets.get(1), suggestionList.getSuggestionAt(1));
+        assertNotEquals(snippets.get(2), suggestionList.getSuggestionAt(2));
+        assertEquals(newSnippets.get(0), suggestionList.getSuggestionAt(2));
 
         assertTrue(section.isDataStale());
     }
 
     /**
      * Tests that the UI does not update any items of the section if the new list is shorter than
      * what has been viewed.
      */
     @Test
     @Feature({"Ntp"})
     public void testUpdateSectionDoesNothingWhenNewListIsShorterThanItemsSeen() {
         List<SnippetArticle> snippets = createDummySuggestions(4, TEST_CATEGORY_ID, "old");
         // Copy the list when passing to the section - it may alter it but we later need it.
         SuggestionsSection section =
                 createSectionWithSuggestions(new ArrayList<>(snippets));
         assertEquals(4, section.getSuggestionsCount());
 
         // Bind the first two suggestions - indicate that they are being viewed.
         // Indices in section are off-by-one (index 0 is the header).
         bindViewHolders(section, 1, 3);
 
         section.updateSuggestions(createSourceFor(createDummySuggestions(1, TEST_CATEGORY_ID)));
         // Even though the new list has just one suggestion, we need to keep the two seen ones
         // around.
         verify(mParent).onItemRangeRemoved(section, 3, 2);
         verify(mParent, never()).onItemRangeInserted(any(TreeNode.class), anyInt(), anyInt());
         assertEquals(2, section.getSuggestionsCount());
-        assertEquals(snippets.get(0), section.getSuggestionAt(1));
-        assertEquals(snippets.get(1), section.getSuggestionAt(2));
+        SuggestionsList suggestionList = section.getSuggestionListForTesting();
+        assertEquals(snippets.get(0), suggestionList.getSuggestionAt(0));
+        assertEquals(snippets.get(1), suggestionList.getSuggestionAt(1));
 
         assertTrue(section.isDataStale());
     }
 
     /**
      * Tests that the UI does not update any items of the section if the current list is shorter
      * than what has been viewed.
      */
     @Test
     @Feature({"Ntp"})
     public void testUpdateSectionDoesNothingWhenCurrentListIsShorterThanItemsSeen() {
         List<SnippetArticle> snippets = createDummySuggestions(3, TEST_CATEGORY_ID, "old");
         // Copy the list when passing to the section - it may alter it but we later need it.
         SuggestionsSection section =
                 createSectionWithSuggestions(new ArrayList<>(snippets));
         assertEquals(3, section.getSuggestionsCount());
 
         // Bind the first two suggestions - indicate that they are being viewed.
         // Indices in section are off-by-one (index 0 is the header).
         bindViewHolders(section, 1, 3);
 
         // Remove last two items.
-        section.removeSuggestionById(section.getSuggestionAt(3).mIdWithinCategory);
-        section.removeSuggestionById(section.getSuggestionAt(2).mIdWithinCategory);
+        SuggestionsList suggestionList = section.getSuggestionListForTesting();
+        section.removeSuggestionById(suggestionList.getSuggestionAt(2).mIdWithinCategory);
+        section.removeSuggestionById(suggestionList.getSuggestionAt(1).mIdWithinCategory);
         reset(mParent);
 
         assertEquals(1, section.getSuggestionsCount());
 
         section.updateSuggestions(createSourceFor(createDummySuggestions(4, TEST_CATEGORY_ID)));
         // We do not touch the current list if all has been seen.
         verify(mParent, never()).onItemRangeRemoved(any(TreeNode.class), anyInt(), anyInt());
         verify(mParent, never()).onItemRangeInserted(any(TreeNode.class), anyInt(), anyInt());
         assertEquals(1, section.getSuggestionsCount());
-        assertEquals(snippets.get(0), section.getSuggestionAt(1));
+        assertEquals(snippets.get(0), suggestionList.getSuggestionAt(0));
 
         assertTrue(section.isDataStale());
     }
 
     /**
      * Tests that the UI does not update when the section has been viewed.
      */
     @Test
     @Feature({"Ntp"})
     public void testUpdateSectionDoesNothingWhenAllSeen() {
@@ skipping 188 matching lines @@
         verify(section.getCategoryInfo(),
                 (action == ContentSuggestionsAdditionalAction.VIEW_ALL ? times(1) : never()))
                 .performViewAllAction(navDelegate);
         verify(suggestionsSource,
                 (action == ContentSuggestionsAdditionalAction.FETCH ? times(1) : never()))
                 .fetchSuggestions(anyInt(), any(String[].class));
     }
 
     private static void verifySnippets(SuggestionsSection section, List<SnippetArticle> snippets) {
         assertEquals(snippets.size(), section.getSuggestionsCount());
-        // Indices in section are off-by-one (index 0 is the header).
-        int index = 1;
+        SuggestionsList suggestionsList = section.getSuggestionListForTesting();
+
+        int index = 0;
         for (SnippetArticle snippet : snippets) {
-            assertEquals(snippet, section.getSuggestionAt(index++));
+            assertEquals(snippet, suggestionsList.getSuggestionAt(index++));
         }
     }
 }