public void Delete()
        {
            //Arrange
            var idForRemove = 1;

            _mock.Setup(s => s.Delete(It.IsAny <int>())).Returns <int>(id =>
            {
                var removeExercise = _exercises.Find(ex => ex.Id == id);
                _exercises.Remove(removeExercise);

                return(new OperationResult
                {
                    Succeed = true,
                    ResultItemId = id
                });
            });

            //Act
            var result          = _exerciseController.Delete(idForRemove);
            var operationResult = result as OkNegotiatedContentResult <IOperationResult>;

            //Assert
            Assert.IsInstanceOfType(result, typeof(OkNegotiatedContentResult <IOperationResult>));
            Assert.IsTrue(operationResult.Content.Succeed);
            Assert.IsTrue(operationResult.Content.ResultItemId > 0);
            Assert.IsFalse(_exercises.Any(ex => ex.Id == operationResult.Content.ResultItemId));
        }