Unit Testing With xUnit And Moq In ASP.NET Core

In the web API project let's add a file "EmployeeController.cs" [Have attached the project here.]

[Route("api/[controller]")]
[ApiController]
public class EmployeeController : ControllerBase
{
    private IGenericRepository<Employee> repo = null;

    public EmployeeController(IGenericRepository<Employee> repo)
    {
        this.repo = repo;
    }

    [HttpGet]
    [Route("GetEmployee")]
    public ActionResult<IEnumerable<Employee>> GetEmployee()
    {
        var model = repo.GetAll();
        return Ok(model);
    }

    [HttpGet("GetEmployeeById/{id}")]
    public  ActionResult<Employee> GetEmployeeById(long id)
    {
        Employee employee = repo.GetById(id);
        if(employee == null)
        {
            return NotFound("The Employee record couldn't be found.");
        }
        return Ok(employee);
    }

    [HttpPost("CreateEmployee")]
    public ActionResult<Employee> CreateEmployee(Employee employee)
    {
        if(employee == null)
        {
            return BadRequest("Employee is null");
        }
        repo.Insert(employee);
        return CreatedAtRoute("GetEmployeeById", new { Id = employee.EmployeeId}, employee);
    }

    [HttpPut]
    public IActionResult Put(Employee employee)
    {
        if(employee == null)
        {
            return BadRequest("Employee is null");
        }
        repo.Update(employee);
        return NoContent();
    }

    public bool checkIfUserCanBeVoter(int age)
    {
        return (age >= 18) ? true : false; 
    }
}

We will also add an interface "IGenericRepository" and its concrete class "GenericRepository".

IGenericRepository.cs

public interface IGenericRepository<T> where T : class
{
    IEnumerable<T> GetAll();
    T GetById(object id);
    void Insert(T obj);
    void Update(T obj);
    void Delete(object id);
    void save();
}

GenericRepository.cs

public class GenericRepository<T> : IGenericRepository<T> where T : class
{
    private readonly ApplicationContext _context = null;

    /// <summary>
    /// as the class here is Generic so we can't access the model directly
    /// so creating a DbSet depending on the T generic class
    /// </summary>
    private DbSet<T> table = null;

    public GenericRepository(ApplicationContext context)
    {
        _context = context;
        table = _context.Set<T>();
    }
    public void Delete(object id)
    {
        throw new NotImplementedException();
    }

    public IEnumerable<T> GetAll()
    {
        return table.ToList();
    }

    public T GetById(object id)
    {
        return table.Find(id);
    }

    public void Insert(T obj)
    {
        table.Add(obj);
        _context.SaveChanges();
    }

    public void save()
    {
        throw new NotImplementedException();
    }

    public void Update(T obj)
    {
        table.Attach(obj);
        _context.Entry(obj).State = EntityState.Modified;
        _context.SaveChanges();
    }
}

and Employee Model class.

Employee.cs

public class Employee
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long EmployeeId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime DateOfBirth { get; set; }
    public string PhoneNumber { get; set; }
    public string Email { get; set; }
}

Creating tests on the test project

Now let's write some tests for our EmployeeController class. For this first install moq library in our xUnit project using the Nuget packager Manager.

Add a new class in the xUnit project named "EmployeeControllerTest.cs".

public class EmployeeControllerTests
{
    private readonly Mock<IGenericRepository<Employee>> service;
    public EmployeeControllerTests()
    {
        service = new Mock<IGenericRepository<Employee>>();
    }
    [Fact]
    //naming convention MethodName_expectedBehavior_StateUnderTest
    public void GetEmployee_ListOfEmployee_EmployeeExistsInRepo()
    {
        //arrange
        var employee = GetSampleEmployee();
        service.Setup(x => x.GetAll())
            .Returns(GetSampleEmployee);
        var controller = new EmployeeController(service.Object);

        //act
        var actionResult = controller.GetEmployee();
        var result = actionResult.Result as OkObjectResult;
        var actual = result.Value as IEnumerable<Employee>;

        //assert
        Assert.IsType<OkObjectResult>(result);
        Assert.Equal(GetSampleEmployee().Count(), actual.Count());
    }

    private List<Employee> GetSampleEmployee()
    {
        List<Employee> output = new List<Employee>
        {
            new Employee
            {
                FirstName = "Jhon",
                LastName = "Doe",
                PhoneNumber = "01682616789",
                DateOfBirth = DateTime.Now,
                Email = "[email protected]",
                EmployeeId = 1
            },
            new Employee
            {
                FirstName = "Jhon1",
                LastName = "Doe1",
                PhoneNumber = "01682616787",
                DateOfBirth = DateTime.Now,
                Email = "[email protected]",
                EmployeeId = 4
            },
            new Employee
            {
                FirstName = "Jhon2",
                LastName = "Doe2",
                PhoneNumber = "01682616787",
                DateOfBirth = DateTime.Now,
                Email = "[email protected]",
                EmployeeId = 5
            }
        };
        return output;
    }
}

Explanation

Line 6 - If you look into our EmployeeController you can see that this Controller has a dependency in the "IGenericRepository<Employee>" so in the constructor we tried to Mock this IGenericRepository<Employee> class so that we can test the controller in isolation. So we created a mocking object by "Mock<IGenericRepository<Employee>>" and make it global to use for testing through the test class.

Line 10 - we are trying to test our "GetEmployee()" method and decorate it with the [Fact] attribute to make it a part of the test runner

Line 13 - Created some sample Employees.

Line 14 - Instructing a mock object that if a certain method is called then it can answer with a certain response. Herewith "Setup()" which method can be called and by the "Returns()" we define certain responses for that specific call. For example: we use "service.Setup(x => x.GetAll()).Returns(GetSampleEmployee);" we define if GetAll() method it called then provide them with the "GetSampleEmployee()" which basically returns a list of dummy employee.

Line 16 - Creating an instance of the Controller class providing its a dependency to the IGenericRepository<Employee>.

Line 19 - calling the GetEmployee() method.

Line 24 - Checking whether the method returns us the Status 200 OK.

Line 25 - Comparing the number of employee count between the actual and the expected list of employees.

Let's create some other tests for this EmployeeController,

public class EmployeeControllerTests
{
    private readonly Mock<IGenericRepository<Employee>> service;
    public EmployeeControllerTests()
    {
        service = new Mock<IGenericRepository<Employee>>();
    }
    [Fact]
    //naming convention MethodName_expectedBehavior_StateUnderTest
    public void GetEmployee_ListOfEmployee_EmployeeExistsInRepo()
    {
        //arrange
        var employee = GetSampleEmployee();
        service.Setup(x => x.GetAll())
            .Returns(GetSampleEmployee);
        var controller = new EmployeeController(service.Object);

        //act
        var actionResult = controller.GetEmployee();
        var result = actionResult.Result as OkObjectResult;
        var actual = result.Value as IEnumerable<Employee>;

        //assert
        Assert.IsType<OkObjectResult>(result);
        Assert.Equal(GetSampleEmployee().Count(), actual.Count());
    }

    [Fact]
    public void GetEmployeeById_EmployeeObject_EmployeewithSpecificeIdExists()
    {
        //arrange
        var employees = GetSampleEmployee();
        var firstEmployee = employees[0];
        service.Setup(x => x.GetById((long)1))
            .Returns(firstEmployee);
        var controller = new EmployeeController(service.Object);

        //act
        var actionResult = controller.GetEmployeeById((long)1);
        var result = actionResult.Result as OkObjectResult;

        //Assert
        Assert.IsType<OkObjectResult>(result);

        result.Value.Should().BeEquivalentTo (firstEmployee);
    }

    [Fact]
    public void GetEmployeeById_shouldReturnBadRequest_EmployeeWithIDNotExists()
    {
        //arrange
        var employees = GetSampleEmployee();
        var firstEmployee = employees[0];
        service.Setup(x => x.GetById((long)1))
            .Returns(firstEmployee);
        var controller = new EmployeeController(service.Object);

        //act
        var actionResult = controller.GetEmployeeById((long)2);

        //assert
        var result = actionResult.Result;
        Assert.IsType<NotFoundObjectResult>(result);
    }

    [Theory]
    [InlineData(18)]
    [InlineData(20)]
    public void checkIfUserCanBeVoter_true_ageGreaterThan18(int age)
    {
        //arrange
        var controller = new EmployeeController(null);

        //act
        var actual = controller.checkIfUserCanBeVoter(age);

        //Assert
        Assert.True(actual);

    }

    [Theory]
    [InlineData(17)]
    [InlineData(15)]
    public void checkIfUserCanBeVoter_true_ageLessThan18(int age)
    {
        //arrange
        var controller = new EmployeeController(null);

        //act
        var actual = controller.checkIfUserCanBeVoter(age);

        //Assert
        Assert.False(actual);

    }

    [Fact]
    public void CreateEmployee_CreatedStatus_PassingEmployeeObjectToCreate()
    {
        var employees = GetSampleEmployee();
        var newEmployee = employees[0];
        var controller = new EmployeeController(service.Object);
        var actionResult = controller.CreateEmployee(newEmployee);
        var result = actionResult.Result;
        Assert.IsType<CreatedAtRouteResult>(result); 
            
    }

    private List<Employee> GetSampleEmployee()
    {
        List<Employee> output = new List<Employee>
        {
            new Employee
            {
                FirstName = "Jhon",
                LastName = "Doe",
                PhoneNumber = "01682616789",
                DateOfBirth = DateTime.Now,
                Email = "[email protected]",
                EmployeeId = 1
            },
            new Employee
            {
                FirstName = "Jhon1",
                LastName = "Doe1",
                PhoneNumber = "01682616787",
                DateOfBirth = DateTime.Now,
                Email = "[email protected]",
                EmployeeId = 4
            },
            new Employee
            {
                FirstName = "Jhon2",
                LastName = "Doe2",
                PhoneNumber = "01682616787",
                DateOfBirth = DateTime.Now,
                Email = "[email protected]",
                EmployeeId = 5
            }
        };
        return output;
    }
}

Now let's go to the "Test Explorer" and run our tests.

So, this way we can use moq in our unit tests. And with this, the introduction to the unit testing journey ends here.

Happy coding!!!