public void TestAdd()
        {
            // Arrange
            var mockRepo = new Mock<IGenericRepository>();
            mockRepo
                .Setup(repo => repo.Find<Variable>(It.IsAny<object[]>()))
                .Returns((object[] keys) => {
                    var name = (string)keys[0];
                    return new Variable {
                        Name = name,
                        Value = Variables[name]
                    };
                });
            var calculatorService = new CalculatorService(mockRepo.Object);

            // Act
            var result = calculatorService.Add("cat", "dog");

            // Assert
            Assert.AreEqual(8.5, result);
        }
 public CalculatorController(CalculatorService service)
 {
     _service = service;
 }