src/test/java/com/google/android/libraries/feed/basicstream/internal/scroll/ScrollRestorerTest.java

// Copyright 2018 The Feed Authors.
//
// 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 com.google.android.libraries.feed.basicstream.internal.scroll;

import static com.google.android.libraries.feed.basicstream.internal.scroll.ScrollRestorer.nonRestoringRestorer;
import static com.google.common.truth.Truth.assertThat;
import static org.mockito.ArgumentMatchers.anyBoolean;
import static org.mockito.ArgumentMatchers.anyLong;
import static org.mockito.ArgumentMatchers.eq;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
import static org.mockito.MockitoAnnotations.initMocks;

import android.app.Activity;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import com.google.android.libraries.feed.api.host.config.Configuration;
import com.google.android.libraries.feed.api.host.config.Configuration.ConfigKey;
import com.google.android.libraries.feed.sharedstream.proto.ScrollStateProto.ScrollState;
import com.google.android.libraries.feed.sharedstream.scroll.ScrollListenerNotifier;
import com.google.android.libraries.feed.testing.android.LinearLayoutManagerForTest;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.robolectric.Robolectric;
import org.robolectric.RobolectricTestRunner;

/** Tests for {@link ScrollRestorer}. */
@RunWith(RobolectricTestRunner.class)
public class ScrollRestorerTest {

  private static final int HEADER_COUNT = 3;
  private static final int TOP_POSITION = 4;
  private static final int BOTTOM_POSITION = 10;
  private static final int ABANDON_RESTORE_THRESHOLD = BOTTOM_POSITION;
  private static final int OFFSET = -10;
  private static final ScrollState SCROLL_STATE =
      ScrollState.newBuilder().setPosition(TOP_POSITION).setOffset(OFFSET).build();

  @Mock private ScrollListenerNotifier scrollListenerNotifier;
  @Mock private Configuration configuration;

  private RecyclerView recyclerView;
  private LinearLayoutManagerForTest layoutManager;
  private Context context;

  @Before
  public void setUp() {
    initMocks(this);

    when(configuration.getValueOrDefault(eq(ConfigKey.ABANDON_RESTORE_BELOW_FOLD), anyBoolean()))
        .thenReturn(false);
    when(configuration.getValueOrDefault(
            eq(ConfigKey.ABANDON_RESTORE_BELOW_FOLD_THRESHOLD), anyLong()))
        .thenReturn((long) ABANDON_RESTORE_THRESHOLD);

    context = Robolectric.buildActivity(Activity.class).get();

    recyclerView = new RecyclerView(context);
    layoutManager = new LinearLayoutManagerForTest(context);
    recyclerView.setLayoutManager(layoutManager);
  }

  @Test
  public void testRestoreScroll() {
    ScrollRestorer scrollRestorer =
        new ScrollRestorer(configuration, recyclerView, scrollListenerNotifier, SCROLL_STATE);
    scrollRestorer.maybeRestoreScroll();

    verify(scrollListenerNotifier).onProgrammaticScroll(recyclerView);
    assertThat(layoutManager.scrolledPosition).isEqualTo(TOP_POSITION);
    assertThat(layoutManager.scrolledOffset).isEqualTo(OFFSET);
  }

  @Test
  public void testRestoreScroll_repeatedCall() {
    ScrollRestorer scrollRestorer =
        new ScrollRestorer(
            configuration, recyclerView, scrollListenerNotifier, createScrollState(10, 20));
    scrollRestorer.maybeRestoreScroll();

    layoutManager.scrollToPositionWithOffset(TOP_POSITION, OFFSET);
    scrollRestorer.maybeRestoreScroll();

    verify(scrollListenerNotifier).onProgrammaticScroll(recyclerView);
    assertThat(layoutManager.scrolledPosition).isEqualTo(TOP_POSITION);
    assertThat(layoutManager.scrolledOffset).isEqualTo(OFFSET);
  }

  @Test
  public void testAbandonRestoringScroll() {
    layoutManager.scrollToPositionWithOffset(TOP_POSITION, OFFSET);

    ScrollRestorer scrollRestorer =
        new ScrollRestorer(
            configuration, recyclerView, scrollListenerNotifier, createScrollState(10, 20));
    scrollRestorer.abandonRestoringScroll();
    scrollRestorer.maybeRestoreScroll();

    assertThat(layoutManager.scrolledPosition).isEqualTo(TOP_POSITION);
    assertThat(layoutManager.scrolledOffset).isEqualTo(OFFSET);
  }

  @Test
  public void testGetScrollStateForScrollPosition() {
    layoutManager.firstVisibleItemPosition = TOP_POSITION;
    layoutManager.firstVisibleViewOffset = OFFSET;
    View view = new View(context);
    view.setTop(OFFSET);
    layoutManager.addChildToPosition(TOP_POSITION, view);
    ScrollState restorerScrollState =
        nonRestoringRestorer(configuration, recyclerView, scrollListenerNotifier)
            .getScrollStateForScrollRestore(HEADER_COUNT);
    assertThat(restorerScrollState).isEqualTo(SCROLL_STATE);
  }

  @Test
  public void testGetBundleForScrollPosition_invalidPosition() {
    assertThat(
            nonRestoringRestorer(configuration, recyclerView, scrollListenerNotifier)
                .getScrollStateForScrollRestore(10))
        .isNull();
  }

  @Test
  public void testGetScrollStateForScrollPosition_abandonRestoreBelowFold_properRestore() {
    when(configuration.getValueOrDefault(eq(ConfigKey.ABANDON_RESTORE_BELOW_FOLD), anyBoolean()))
        .thenReturn(true);

    layoutManager.firstVisibleItemPosition = TOP_POSITION;
    layoutManager.firstVisibleViewOffset = OFFSET;
    layoutManager.lastVisibleItemPosition = BOTTOM_POSITION;
    View view = new View(context);
    view.setTop(OFFSET);
    layoutManager.addChildToPosition(TOP_POSITION, view);
    ScrollState restorerScrollState =
        nonRestoringRestorer(configuration, recyclerView, scrollListenerNotifier)
            .getScrollStateForScrollRestore(HEADER_COUNT);
    assertThat(restorerScrollState).isEqualTo(SCROLL_STATE);
  }

  @Test
  public void testGetScrollStateForScrollPosition_abandonRestoreBelowFold_badBottomPosition() {
    when(configuration.getValueOrDefault(eq(ConfigKey.ABANDON_RESTORE_BELOW_FOLD), anyBoolean()))
        .thenReturn(true);

    layoutManager.firstVisibleItemPosition = TOP_POSITION;
    layoutManager.firstVisibleViewOffset = OFFSET;
    View view = new View(context);
    view.setTop(OFFSET);
    layoutManager.addChildToPosition(TOP_POSITION, view);
    ScrollState restorerScrollState =
        nonRestoringRestorer(configuration, recyclerView, scrollListenerNotifier)
            .getScrollStateForScrollRestore(HEADER_COUNT);
    assertThat(restorerScrollState).isNull();
  }

  @Test
  public void testGetScrollStateForScrollPosition_abandonRestoreBelowFold_restorePastThreshold() {
    when(configuration.getValueOrDefault(eq(ConfigKey.ABANDON_RESTORE_BELOW_FOLD), anyBoolean()))
        .thenReturn(true);

    layoutManager.firstVisibleItemPosition = TOP_POSITION;
    layoutManager.firstVisibleViewOffset = OFFSET;
    layoutManager.lastVisibleItemPosition = ABANDON_RESTORE_THRESHOLD + HEADER_COUNT + 1;
    View view = new View(context);
    view.setTop(OFFSET);
    layoutManager.addChildToPosition(TOP_POSITION, view);
    ScrollState restorerScrollState =
        nonRestoringRestorer(configuration, recyclerView, scrollListenerNotifier)
            .getScrollStateForScrollRestore(HEADER_COUNT);
    assertThat(restorerScrollState).isNull();
  }

  private ScrollState createScrollState(int position, int offset) {
    return ScrollState.newBuilder().setPosition(position).setOffset(offset).build();
  }
}