Being Test-Driven: It's not really about testing
- 1. Being Test-Driven It’s not really about testing Raj Indugula George Lively Raj.Indugula@lithespeed.com George.lively@lithespeed.com Twitter: @lithespeed
- 2. 2 What is the point of test-driven development?
- 3. • Driving Common Understanding with Behavior Driven Development • Driving Better Design with Test- Driven Development • Tying it all together • Q&A Outline “The speed of development is the speed of getting an idea from one brain to another” – Alistair Cockburn 3
- 4. BDD IS BUILDING THE RIGHT THING Behavior-Driven Development (BDD)
- 5. Behavior Driven Development (BDD) 5 Collaboration and conversation to discover essential requirements and identify uncertainty Using rules & examples Expressed in a common language to build a shared understanding To deliver software that matters
- 6. Behavior Driven Development (BDD) 6 Collaboration and conversation to discover essential requirements and identify uncertainty Using rules & examples Expressed in a common language to build a shared understanding To deliver software that matters
- 8. BDD IS THE ART OF USING RULES & EXAMPLES IN CONVERSATIONS TO ILLUSTRATE BEHAVIOR 8
- 9. 9 Different Viewpoints, Shared Understanding 9 Business, Developer, Tester Shared understanding All agree it is ready to be implemented THREE AMIGOS 9 Example Mapping, Matt Wynne Depositor can withdraw cash Limited by amount on deposit Subject to daily and transaction limits Scenario with sufficient funds Limited by daily limit of $500 What is the transaction limit? Cash is dispensed in $10 increments with $20 bills favored Scenario with insufficient funds Fully stocked scenario when withdrawal of $50 results in 2 $20 bills and 1 $10 bill When out of $20s, withdrawal of $50 results in 5 $10 bills Acceptance Scenarios Acceptance Criteria
- 10. 10 CAPTURE THE CONVERSATIONS TO DRIVE DEVELOPMENT
- 11. 11 Feature: ATM withdrawals Our ATM allows depositors to withdraw their funds in cash Rules: Withdrawals are limited by amount on deposit Withdrawals are subject to daily and transaction withdrawal limits Cash is dispensed in $10 increments with $20 bills favored Scenario: Sufficient funds allows successful withdrawal Given a depositor has $2000 on deposit When the depositor requests $200 Then the ATM dispenses $200 And the depositor’s balance is reduced to $1800 … DocumentationHuman readable Structured and keyword-based Allows automation Gherkin
- 12. 12 AUTOMATE SPECIFICATIONS AS NEEDED Test Framewor k Integratio n Gherkin Scenarios Specification expressed in common language Step Definitions “Glue” code that ties specification to System under Test Cucumber, SpecFlow, etc.
- 14. Test-Driven Development (TDD) TDD IS BUILDING THE THING RIGHT
- 15. Reimagine our thinking… 15 How we typically write tests… 1. Think about implementation 2. Write code (fields & methods) 3. Write some test cases to verify behavior Instead, what if we… 1. Write a test to capture expected behavior? 2. Think about implementation to meet expectation? 3. Write code to make the failing test pass? Build functionality incrementally one test at a time…
- 16. Test-Driven Development (TDD) 16 Write a new test Test Fails Write Code Test Passes Clean up code, make sure tests pass start here Style of programming in which three activities are tightly interwoven: coding, testing (in the form of writing unit tests) and design (in the form of refactoring) Developer heartbeat Red – Green - Refactor
- 17. Business Benefits Requirements verification Regression catching Quicker release cycle Reduced Waste
- 18. Developer Benefits Better design choices Prevents gold- plating Confidence / Supports change Momentum
- 19. Extreme Programming (XP) - Kent Beck 19 Feedback & Simplicity
- 20. But there’s no free lunch… 20 Here are some ways that TDD can lead to WORSE design: • In search of speed, developers will lean too heavily on mocks, locking in place their production code and making refactoring more difficult • Developers will build elaborate dependency injection tools and structures, making their design highly complex and unmaintainable. REMEMBER: the emphasis should be on SIMPLE DESIGN, and not just for your application code but also for your test code. Source: https://www.jamesshore.com/Blog/How-Does-TDD-Affect- Design.html
- 21. Source Adaptation: BDD in Action Business Goals Features Rules & Examples Executable specifications Low-level specifications Application Code User stories Only build features that align with business goals Features and stories clarified with rules and examples Guide development & testing. Can be read by whole team Features broken down into smaller user stories. Help plan how we deliver a feature Unit tests aimed mostly at developers Automatable with BDD tools like Cucumber, Specflow Unit testing tools like JUnit, NUnit 21 Principle Activities Summarized
- 22. Source Adaptation: Raj Indugula & George Dinwiddie Scenario: Invalid example Given I am a new user When I select "Abc1*$!-**" as a password Then I can access my account Scenario: Cash dispensed when machine has no $20 bills Given the ATM is out of $20 bills When a depositor withdraws $50 Then the ATM dispenses 5 $10 bills 22 From Test-last to Test-driven conversations Building the right thing Building the thing right
- 23. 23 Being test-driven isn’t really about testing. It’s about specification and design driven through tests