public void GetAllPlanTypes_ShouldReturnAllValidValues_UnderAllConditions() { // Arrange & Act PlanType[] output = CUT.GetAllPlanTypes().ToArray(); // Assert output.ShouldNotBeNull(); output.ShouldNotBeEmpty(); output.ShouldContain(PlanType.Fixed); output.ShouldContain(PlanType.Variable); output.ShouldContain(PlanType.Indexed); }