Use Visual Studio Task List to Create Test Lists for Test Driven Development

Integrated TDD Environment

Introduction

The Visual Studio 2008 SP1 now includes integrated unit testing, making TDD (Test Driven Development or Test Driven Development) easier than ever before. However, if you want to use VS 2008 as a fully-integrated TDD environment, you'll need to make creative use of the Task List.

Test Driven Design and Development

The idea behind TDD is that you write all the code for your application through a series of small steps by creating unit tests. The mantra is, "Never write a single line of code unless you have a test that fails." There are a couple advanatages to doing it this way:

• By doing things in small steps, you can go quicker with less errors
• You create unit tests as you go and rerun them with each coding change, immediately finding any code that gets broken when you add new features

So how do you start?

Like any software project, TDD starts with requirements. What does the software need to do? You take each requirement and generate a "test list," a list of all the criteria that must be met to fulfill the requirement.

The basic TDD process is Red/Green/Refactor:

1. Write a test that fails so that the unit test shows a red light
2. Add code to make the test pass and show a green light
3. Refactor to avoid duplication

Using Visual Studio as TDD Environment

Visual Studio now helps with this process. Visual Studio 2008 Professional Edition now includes the Visual Studio Test Suite (previously only Team Edition had it) which gives you the red and green lights. The Visual Studio editor also includes some built-in refactoring support.

However I would like to do everything within a single IDE if possible. I would prefer to do the Test Lists within my code editor rather than entering them into a spreadsheet, text file, or writting them down on paper. One way to do this is with the Visual Studio Task List.

Visual Studio Task List

The Task List has been part of VS since the original .Net 1.0 release. It provides a mechanism for reminders of things that developers need to complete.

You can open the Task List by selecting it from the View menu. There are two types of tasks: User and Comments. User tasks are things that you enter manually and manage yourself. Comments are created by adding comments with special key words to your code. You can then jump from your task list to the spot in the code where you put the comment.

Visual Studio provides three default tokens for comment tasks:

• TODO: Something that needs to be started or completed. VS will automatically generate some of these, for example when you create a new class it adds, "TODO: Add constructor logic here."
• HACK: Quickly written code that needs to be reworked later.
• UNDONE: Code changes that have been reversed.

To create a comment you enter the comment characters, (// in C#, ' in VB), the token followed by a colon (:) and the text of the task.

We can use the Task List for TDD by adding our own comment token: TEST.

To add a custom token we select options from the Tools menu and then select Task List under Environment:

To add our new token we enter TEST in the Name field and then click Add. We can now add a Test Task anywhere in our code by starting a comment, typing TEST: and a description of our test. Now you can create your TDD test list right inside the VS source code editor for your test project.: // TEST: Verify a user can add a new record // TEST: Verify a user can update an existing record // TEST: Verify a user can delete an existing record // TEST: Verify an error occurs when add a duplicate record To implement each test you add your test code after the comment and delete the TEST: part of the comment to remove the test from the Task List:

// Verify a user can add a new record [TestMethod()] public void AddNewRecord() { // TODO: Add Test Logic }

As you think of new tests while your in the middle of coding others you add a TEST: comment and then go back to what you're working on. Later, you can double-click on an item in the Task List to go directly to that spot in the code.

In my next blog post I'll walk you through a simple example.