Interview question prompt for: http://www.heyswegner.com/2015/04/good-interview-questions.html

FlightsIsolatedOnMultipleFeatureAreas.cs

[TestMethod]
public void FlightsIsolatedOnMultipleFeatureAreas()
{
    var abFlight = new Flight(new[] { "A", "B" }, trafficPercent: 100);
    var bcFlight = new Flight(new[] { "B", "C" }, trafficPercent: 100);
    var cFlight = new Flight(new[] { "C" }, trafficPercent: 100);

    _assignmentService.Add(abFlight);
    _assignmentService.Add(bcFlight);
    _assignmentService.Add(cFlight);

    var assignments = _assignmentService.GetFlights(_user).ToList();
    Assert.AreEqual(2, assignments.Count);
    CollectionAssert.Contains(assignments, abFlight);
    CollectionAssert.Contains(assignments, cFlight);
}