@Test
public void testPrevious_doesNotUpdatePositionAtEndOfTimeline() {
final Timeline<TestItem> fakeEndTimeline =
new FakeItemTimeline(ZERO_ITEMS, ANY_POSITION, ANY_POSITION);
delegate = new TimelineDelegate<>(fakeEndTimeline);
delegate.timelineStateHolder.setPreviousCursor(new TimelineCursor(null, null));
delegate.previous();
assertNull(delegate.timelineStateHolder.positionForPrevious());
}
@Test
public void testPrevious_updatesPositionForPrevious() {
final Timeline<TestItem> fakeTimeline =
new FakeItemTimeline(NUM_ITEMS, TEST_MIN_POSITION, ANY_POSITION);
delegate = new TimelineDelegate<>(fakeTimeline);
assertNull(delegate.timelineStateHolder.positionForPrevious());
delegate.previous();
assertEquals(TEST_MIN_POSITION, delegate.timelineStateHolder.positionForPrevious());
}
@Test
public void testPrevious_addsItems() {
final Timeline<TestItem> fakeTimeline =
new FakeItemTimeline(NUM_ITEMS, ANY_POSITION, ANY_POSITION);
delegate = new TimelineDelegate<>(fakeTimeline, mockObservable, null);
delegate.refresh(null);
// refresh loads latest items (notifyChange)
delegate.previous();
// assert items are added and notifyChanges is called again
assertEquals(2 * NUM_ITEMS, delegate.getCount());
verify(mockObservable, times(2)).notifyChanged();
}
@Test
public void testPrevious_doesNotAddItemsAtEndOfTimeline() {
// when a Timeline successfully returns an empty set of items, its end has been reached
LinkedList<TestItem> initialItems = new LinkedList<>();
final int INITIAL_COUNT = 5;
initialItems = TestItem.populateList(initialItems, INITIAL_COUNT);
final Timeline<TestItem> fakeEndTimeline =
new FakeItemTimeline(ZERO_ITEMS, ANY_POSITION, ANY_POSITION);
delegate = new TimelineDelegate<>(fakeEndTimeline, mockObservable, initialItems);
delegate.previous();
// assert no items are added and notifyChanged is not called
assertEquals(INITIAL_COUNT, delegate.getCount());
verifyZeroInteractions(mockObservable);
}