By Mike Hill, Joshua Kerievsky

How can you increase the speed and joy of software development while decreasing the stress of modifying code? Test-Driven Development can help! TDD is a rhythm, a design technique, a development process and a revolution, all in one.

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Code with Confidence: Learn & practice Test-Driven Development to improve your code quality and speed. Learn more...
Instant Critiques: Take a TDD exercise and get instant feedback from our automated band of experts. Learn more...

Expert Videos: Learn tools & techniques by watching short videos from industry experts. Learn more...
Integrated Forums: Ask questions, get expert replies and read fascinating discussions. Learn more...


  • 3-5 hours of content
  • 110 pages
  • A Catalog of TDD Patterns
  • 14 Videos
  • 2 Exercises
  • 3 Interactive Quizzes
  • A TDD Flowchart
  • Automated TDD Critique
  • Platform-independent code
  • Support for Visual Studio
  • Support for Eclipse CDT
  • Uses Google Test


You Are Here 3
Test-Driven Development In One Sentence 4
Some TDD -Isms 5
Why Adopt TDD? 6
This Album 7
A First Look At The TDD Cycle ← Click to Preview 9
Keyword: Red 10
Getting To Red 11
Keyword: Green 12
Getting To Green 13
It Isn't Easy Getting to Green 14
Keyword: Refactor 15
Refactorings In The TDD Cycle 16
Refactoring Is Critical 17
Keyword: Integrate 18
Integration 19
Continuous Integration 20
This Will Never Work! 22
We Only Have Hard Defects Here 23
It All Boils Down to Expectations… 24
TDD Will Not Validate Our System 25
Tests+Code > Just Code ← Click to Preview 26
An End To The Arguments? 27
Introducing TDD Patterns 29
Essence First 30
Essence First Video 31
Test First 32
Test First Video 33
Assert First 34
Assert First Video 35
Frame First ← Click to Preview 36
Frame First Video ← Click to Preview 37
Do The Simplest Thing That Could Possibly Work 38
Do The Simplest Thing That Could Possibly Work Video 39
Break It To Make It 40
Break It To Make It Video 41
Refactor Mercilessly 42
Refactor Mercilessly Video 43
Test Driving 44
Test Driving Video 45
Summary of the Patterns 46
TDD Cycle Deeper Look Video 48
Why Record? 50
The Steps To Take 51
Step 1. Install the GTest Result Viewer (Optional) 52
Step 2. Download the Exercise 53
Step 3. Import the Exercise 54
Step 4. Perform the Exercise 55
Step 5. Upload the Archive 56
Step 6. Critique Your Performance 57
Remaining Issues 58
Carry On! 59
The Purpose of this Exercise 61
Critiquing Your Performance 62
Proceed with Caution 63
Installing Our Plugin 64
Download the Code 65
Exercise Instructions 66
Upload Your Work 67
A Graph of Your TDD Activity 68
Your Critique Results 69
Your Customized Feedback 70
Our Solution 71
TDDing Big Bill's Billing System ← Click to Preview 73
Some Advice Before You Begin 74
Installing Our Plugin 75
Setup 76
An Exercise Composed of Four Tasks 77
Task 1: Calculate A Simple Phone Bill 78
Task 2: Calculate Excess Minutes 79
Task 3: Calculate Family Discount 80
Task 4: Calculate Complete Phone Bill 81
Task 1 Solution ← Click to Preview 82
Task 2 Solution 83
Task 3 Solution 84
Task 4 Solution 85
An Alternative Solution 86
A Third Solution 87
The Secret To TDDing GUIs 89
The Open Dialog 90
A Naive Implementation 91
The Thick Black Line 92
Model: The Dialog Without The GUI Parts 93
Models Don't Speak GUI 94
View: All GUI, All The Time 95
How The Split Helps 96
The Meta-Pattern: Split Along TDD-Happy Lines 97
Does TDD Eliminate Formal Design? 99
What Is Design, Anyway? 100
A Massively Experienced TDD Team ← Click to Preview 101
Where's My Design? 102
Inverted Design? 103
Distributed Design 104
Incremental Design 105
The Stepwise Premise 106
Architecture 107
Architecture Story 108
Conclusion 110

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  • Internet Explorer 8+
  • Latest Chrome
  • Latest Safari

Operating Systems

  • Windows
  • Linux
  • Mac OS X

Development Tools

You can use whatever developments tools you prefer. If you do use an IDE (Integrated Development Environment), many (though not all) of our labs come with projects pre-configured for Eclipse, IntelliJ and Visual Studio.

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