EmployeeControllerTests.cs

[TestFixture]
public class when_getting_employee
{
    [Test]
    public void then_should_return_ok_result_given_employee_id()
    {
        // Arrange
        var controller = new EmployeeController(new Mock<IEmployeeRepository>().Object);

        // Act
        var result = controller.Get(1);

        // Assert
        Assert.That(result, Is.TypeOf<OkNegotiatedContentResult<Employee>>());
    }
    [Test]
    public void then_should_return_ok_result_containing_employee_given_employee_id()
    {
        // Arrange
        var employeeRepository = new Mock<IEmployeeRepository>();
        var employee = new Employee();
        employeeRepository.Setup(repository => repository.Get(1)).Returns(employee);

        var controller = new EmployeeController(employeeRepository.Object);

        // Act
        var result = controller.Get(1);
        

        // Assert
        Assert.That((result as OkNegotiatedContentResult<Employee>).Content, Is.EqualTo(employee));
    }
}