public void Delete_Returns_Null_When_WorkoutDoesNotExist()
            {
                // Arrange
                const int id = 1;

                // Act
                var result = RepositoryUnderTest.Delete(id);

                // Assert
                Assert.Null(result);
            }
            public void Delete_Deletes_And_Returns_Workout()
            {
                // Arrange
                var expectedWorkout = new Workout {
                    Name = "Test workout 01"
                };

                TrainingPlanContextMock.Workouts.Add(expectedWorkout);
                TrainingPlanContextMock.SaveChanges();
                var id = expectedWorkout.Id;

                // Act
                var result = RepositoryUnderTest.Delete(id);

                // Assert
                Assert.Same(expectedWorkout, result);
            }