public void EmptyExceptions() { Deque <double> d = new Deque <double>(); try { d.GetAtFront(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } try { d.GetAtBack(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } try { d.RemoveFromFront(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } try { d.RemoveFromBack(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } d.AddToBack(2.3); d.RemoveFromFront(); try { d.GetAtFront(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } try { d.GetAtBack(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } try { d.RemoveFromFront(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } try { d.RemoveFromBack(); Assert.Fail("should throw"); } catch (Exception e) { Assert.IsTrue(e is InvalidOperationException); } }