public void TimeSegmentViewModel_WhenEndTimeIsMissing_FormatsDurationCorrectly()
        {
            // Arrange
            var tsvm = new TimeSegmentViewModel(new TimeSegment
            {
                StartTime = new DateTime(2017, 3, 1, 10, 0, 0)
            }, new ValidationMessageViewModel());

            // Act
            var duration = tsvm.Duration;

            // Assert
            Assert.Equal(string.Empty, duration);
        }
        public void TimeSegmentViewModel_WhenBothStartAndEndTimeExist_FormatsDurationCorrectly()
        {
            // Arrange
            var tsvm = new TimeSegmentViewModel(new TimeSegment
            {
                StartTime = new DateTime(2017, 3, 1, 10, 0, 0),
                EndTime   = new DateTime(2017, 3, 1, 11, 15, 35)
            }, new ValidationMessageViewModel());

            // Act
            var duration = tsvm.Duration;

            // Assert
            Assert.Equal("01:15:35", duration);
        }