public async Task GetItemConsistentOnUIThread()
{
var notifier = new MockCollectionChangedNotifier();
var source = new ObservableCollection <string>
{
"zero",
"one",
"two"
};
IItemsViewSource ois = ItemsSourceFactory.Create(source, notifier);
string itemAtPosition2BeforeNotify = string.Empty;
// Add an item from a threadpool thread
await Task.Run(() => {
source.Insert(0, "foo");
// Post a check ahead of the queued update on the main thread
_handler.PostAtFrontOfQueue(() => itemAtPosition2BeforeNotify = (string)ois.GetItem(2));
});
// Check the result on the main thread
var onMainThreadGetItem = await Device.InvokeOnMainThreadAsync(() => (string)ois.GetItem(2));
Assert.That(itemAtPosition2BeforeNotify, Is.EqualTo("two"));
Assert.That(onMainThreadGetItem, Is.EqualTo("one"));
Assert.That(notifier.InsertCount, Is.EqualTo(1));
}
public async Task AddItemCountConsistentOnUIThread()
{
var notifier = new MockCollectionChangedNotifier();
var source = new ObservableCollection <int>();
IItemsViewSource ois = ItemsSourceFactory.Create(source, notifier);
int countBeforeNotify = -1;
// Add an item from a threadpool thread
await Task.Run(() => {
source.Add(1);
// Post a check ahead of the queued update on the main thread
_handler.PostAtFrontOfQueue(() => {
countBeforeNotify = ois.Count;
});
});
// Check the result on the main thread
var onMainThreadCount = await Device.InvokeOnMainThreadAsync(() => ois.Count);
Assert.That(countBeforeNotify, Is.EqualTo(0), "Count should still be reporting no items before the notify resolves");
Assert.That(onMainThreadCount, Is.EqualTo(1));
Assert.That(notifier.InsertCount, Is.EqualTo(1), "Should have recorded exactly one Add");
}
public async Task RemoveitemCountConsistentOnUIThread()
{
var notifier = new MockCollectionChangedNotifier();
var source = new ObservableCollection <int> {
1
};
IItemsViewSource ois = ItemsSourceFactory.Create(source, notifier);
int countBeforeNotify = -1;
// Remove an item from a threadpool thread
await Task.Run(() =>
{
source.Remove(1);
// Post a check ahead of the queued update on the main thread
_handler.PostAtFrontOfQueue(() => countBeforeNotify = ois.Count);
});
// Check the result on the main thread
var onMainThreadCount = await Device.InvokeOnMainThreadAsync(() => ois.Count);
Assert.That(countBeforeNotify, Is.EqualTo(1));
Assert.That(onMainThreadCount, Is.EqualTo(0));
Assert.That(notifier.RemoveCount, Is.EqualTo(1));
}
public async Task GetPositionConsistentOnUIThread()
{
var notifier = new MockCollectionChangedNotifier();
var source = new ObservableCollection <string>
{
"zero",
"one",
"two"
};
IItemsViewSource ois = ItemsSourceFactory.Create(source, Application.Current, notifier);
int positionBeforeNotify = -1;
// Add an item from a threadpool thread
await Task.Run(() =>
{
source.Insert(0, "foo");
// Post a check ahead of the queued update on the main thread
_handler.PostAtFrontOfQueue(() => positionBeforeNotify = ois.GetPosition("zero"));
});
// Check the result on the main thread
var onMainThreadGetItem = await Application.Current.Dispatcher.DispatchAsync(() => ois.GetPosition("zero"));
Assert.That(positionBeforeNotify, Is.EqualTo(0));
Assert.That(onMainThreadGetItem, Is.EqualTo(1));
Assert.That(notifier.InsertCount, Is.EqualTo(1));
}
