Test-driven development (TDD) involves writing unit tests before writing application code. TDD promotes writing high-quality code and prevents regressions. It follows a "red-green-refactor" process of writing a failing test, making it pass by writing minimal code, and refactoring the code. Unit test frameworks allow automating tests and isolating code dependencies using techniques like stubs, fakes, and mocks. Tests should be organized into test classes and follow a lifecycle of setup, execution, and teardown.

1. Introduction to
Test First Development
@GomesNayagam

2. Introduction to Developer Testing
Unit Testing Frameworks
Test First Development

3. Benefits
 Higher quality
 Fewer defects
 Living documentation
 Well Crafted code
 Automatic regression harness

4. A unit test confirms functionality
of a small unit of functionality or
component
in a larger system.

5. Unit Test Frameworks

7. How Unit Test Frameworks Work
Unit Test Runner
EXE
Unit Test
My Code My Unit Test Lib Common Lib

8. Test First Development

9. TFD Details
A Jig is a form upon which
something else is built
The jig is the specification for
the thing being built
Remove the jig when ready to
Launch
For software, Jig is built just a moment before it is being used

10. Create a failing test Red
Make the test pass Green
RED Refactor Improve the internal
implementation without
changing the external
contract or behavior
Refactor Green

11. The Tests are the Specs

12. TFD: Writing Unit Tests

13. Test Integration vs.
Organization Unit Tests
Testing the Sad Unit Test
Path Lifecycle

14. Unit Test or Integration Test

15. Test Organization - xUnit

16. Test Lifecycle nUnit
TestFixtureSetup
SetUp
Test
TearDown
TestFixtureTearDown

17. Setting Up A Test Project
Tests live in a separate class library project

18. A First Test
Using Nunit.Framework
Namespace Domain.Tests
{
[TestFixture]
public class FirstTestFixture
{
[Test]
public void AFirstTest()
{
Assert.IsTrue(true,”true is true!”);
}
}
}

19. TFD - Assertions
Use one logical assertion per test
[Test]
public void the_order_is_canceled()
{
var customer = CreateCustomer();
Assert.IsNotNull(customer);
customer.PlaceOrder();
Assert.IsTrue(customer.HasOrder);
customer.CancelOrder();
Assert.IsFalse(customer.HasOrder);
}

20. Isolating Code

21. Isolation Techniques
Test Doubles
Isolation by Example

22. Isolation Techniques
Test Method
SUT
Dependency Test Object
Object

23. Faking out the SUT
Test Method
1.Create test specific objects
2.Create the SUT (using Interface)
3. Invoke operation on the SUT
4.Check results of SUT invocation On the SUT

24. Testing Double

25. Dummy
var person = new Person();
person.First = “Homer”;
person.Last = “Simpson”;
Assert.IsNotNull(person.FullName);
var order = new Order();
order.AddLineItem(12, 1);
order.AddLineItem.Add(21, 3);
Assert.AreEqual(2, order.NumLineItems);

26. Stub
public class StubRepo : IOwnerRepository {
public IOwner FindById(int id){}
public IOwner Save(IOwner owner) {
return new Owner();
}
public void Delete(IOwner owner){}
}

27. Fake

28. Mock
 TypeMock
 RhinoMock
 Moq

29. e.g.
using System;
using System.Collections.Generic;
namespace MoqSamples.Models
{
public interface IProductRepository
{
List<IProduct> Select();
IProduct Get(int id);
}
public interface IProduct
{
int Id {get; set;}
string Name { get; set; }
}
}
// Mock a product
var newProduct = new Mock<IProduct>();
newProduct.ExpectGet(p => p.Id).Returns(1);
newProduct.ExpectGet(p => p.Name).Returns("Bushmills");
Assert.AreEqual("Bushmills", newProduct.Object.Name);

30. e.g.
// Mock product repository
var productRepository = new Mock<IProductRepository>();
productRepository.Expect(p => p.Get(1)).Returns(newProduct.Object)
// Act
var productReturned = productRepository.Object.Get(1);
// Assert
Assert.AreEqual("Bushmills", productReturned.Name);
// Mock product repository
var productRepository = new Mock<IProductRepository>();
productRepository
.Expect(p => p.Get(It.IsAny<int>()))
.Returns(newProduct.Object);

31. Summery…
Stick with red
-
Write tests in a green
separate -
project refactor
Keep
Treat test code practicing and
with respect learning

32. Reference
Test Driven Development by Example , Kent Beck, 2002
http://code.google.com/p/moq/wiki/QuickStart
http://stephenwalther.com/blog/archive/2008/06/12/tdd-
introduction-to-moq.aspx
Source: Pluralsight,Google,WIKI