Reactive Testing With AsyncAwait

[Test]
[Timeout(2000)]
public async Task WriteToFile_StreamsChanged()
{
	using (var watcher = new ObservableFileSystemWatcher(c => { c.Path = TempPath; }))
	{
		var firstChanged = watcher.Changed.FirstAsync().ToTask();
		watcher.Start();

		File.WriteAllText(Path.Combine(TempPath, "Changed.Txt"), "foo");

		var changed = await firstChanged;
		Expect(changed.ChangeType, Is.EqualTo(WatcherChangeTypes.Changed));
		Expect(changed.Name, Is.EqualTo("Changed.Txt"));
	}
}

This is a gist of this my post c# async/await makes reactive testing expressive!

Wes, what's the assert library used here? i mean the piece: Exepect(..., Is.EqualTo(...)) Thx