// should set both nextCursor and previousCursor to be non-null
@Test
public void testNextCallback_successFirstReceivedItems() {
delegate = new TimelineDelegate<>(mockTimeline, mockObservable, testItems);
final TimelineStateHolder timelineStateHolder = new TimelineStateHolder();
final TimelineDelegate.NextCallback cb = delegate.new NextCallback(null, timelineStateHolder);
cb.success(new Result<>(new TimelineResult<>(TEST_TIMELINE_CURSOR, testExtraItems), null));
// assert the next TimelineCursor is set on the ScrollStateHolder, previous unchanged
assertEquals(TEST_MAX_POSITION, timelineStateHolder.positionForNext());
assertEquals(TEST_MIN_POSITION, timelineStateHolder.positionForPrevious());
}
// should do nothing
@Test
public void testNextCallback_successReceivedZeroItems() {
delegate = new TimelineDelegate<>(mockTimeline, mockObservable, testItems);
final TimelineStateHolder timelineStateHolder = new TimelineStateHolder();
final TimelineDelegate.NextCallback cb = delegate.new NextCallback(null, timelineStateHolder);
cb.success(
new Result<>(new TimelineResult<>(TEST_TIMELINE_CURSOR, Collections.emptyList()), null));
// assert that the cursors and itemList are left unmodified
assertNull(timelineStateHolder.positionForNext());
assertNull(timelineStateHolder.positionForPrevious());
assertEquals(testItems.size(), delegate.itemList.size());
verifyZeroInteractions(mockObservable);
}
// should prepend result items, set next cursor, and call notifyChanged
@Test
public void testNextCallback_successReceivedItems() {
delegate = new TimelineDelegate<>(mockTimeline, mockObservable, testItems);
final TimelineStateHolder timelineStateHolder =
new TimelineStateHolder(
new TimelineCursor(ANY_POSITION, ANY_POSITION),
new TimelineCursor(ANY_POSITION, ANY_POSITION));
final TimelineDelegate.NextCallback cb = delegate.new NextCallback(null, timelineStateHolder);
cb.success(new Result<>(new TimelineResult<>(TEST_TIMELINE_CURSOR, testExtraItems), null));
// assert the next TimelineCursor is set on the ScrollStateHolder, previous unchanged
assertEquals(TEST_MAX_POSITION, timelineStateHolder.positionForNext());
assertEquals(ANY_POSITION, timelineStateHolder.positionForPrevious());
// assert that extra items were prepended in reverse order
assertEquals(TOTAL_ITEMS, delegate.itemList.size());
assertEquals(TEST_ITEM_4, delegate.getItem(0));
assertEquals(TEST_ITEM_3, delegate.getItem(1));
assertEquals(TEST_ITEM_2, delegate.getItem(2));
assertEquals(TEST_ITEM_1, delegate.getItem(3));
// assert observer's notifyChanged is called
verify(mockObservable).notifyChanged();
}