private void FilterTests(string searchInput)
{
if (string.IsNullOrWhiteSpace(searchInput))
{
ObservableTests = new ObservableCollectionExtended <Test>(_allTests);
}
else
{
var smartSearch = new SmartSearch <Grade>();
var matchingIDs = smartSearch.Search(_allTests, searchInput);
ObservableTests =
new ObservableCollectionExtended <Test>(
_allTests.Where(g => matchingIDs.Contains(g.ID)));
}
}