Introduction to TDD and BDD Presented to my colleagues at ING Direct Spain

1. INTRODUCTION TO BDD
(Behaviour-Driven Development)
Luis García Castro

2. TESTING
2
Why is testing so important ?
We can’t avoid to have bugs in our applications, but we must
limit its presence and impact (and not only in release date)
Inception Design Development Acceptance Maintenance

3. 3
Benefits of Unit Testing
Tests create a feedback loop that informs the developer whether the
product is working or not.
●
Unit tests are fast
●
Unit tests are reliable
●
Unit tests isolate failures
But tests made at the end of the project are only useful to exceed
the mandatory coverage, they don’t provide many other benefits

4. 4
What is TDD ?
TDD is a not just “adding tests first”, it’s a workflow

5. 5
Benefits of TDD
TDD is the best way to
discover how complex your
code is becoming
●
Do you need to mock 7
objects for a unit test?
●
Do you have a setup
method of >15 lines?
●
Are you able to test all your
code?
By writing test first:
●
You are becoming a
consumer of your own API
●
You are forced to think
what responsibilities the
given object should have
●
You are creating a safety
net for everyone

6. Acceptance tests
Customer tests
…
BDD
Unit tests
TDD
Sonar
Lint
...
6
Is it enough with unit tests ?
Code Right vs Right Code

7. 7
What is BDD ?
Behaviour-Driven Development
“It’s about focusing on the behaviour of an application from
the point of view of its stakeholders”
Dan North

8. 8
Who is a stakeholder ?
A stakeholder is anyone
who cares about:
●
What the application does
●
How much it costs
●
Whether it is secure
●
Whether the network will
hold
●
Whether it complies with the
law
●
How easy it is to deploy and
diagnose
●
How well it is written and
architected
●
How easy it is to change

9. 9
A more formal definition of BDD
BDD is a second-generation, outside-in, pull-based, multiple-
stakeholder, multiple-scale, high-automation, agile
methodology
It describes a cycle of interactions with well-defined outputs,
resulting in the delivery of working, tested software that
matters
Dan North

10. 10
BDD asks for an Outside-In approach
Express a requirement as a Story
●
As… I want… So that I…
Define acceptance criteria as scenarios made up of steps
●
Given… When… Then...
Automate the scenarios
●
So each step becomes running code

11. 11
BDD is about Comunication
Business
Team
Requirements
Examples to
discuss
Design and create
code specification
Examples to
implement

12. 12
Simple requirements and examples
Feature: Tracking deliveries
As a Customer
I want to see a status of my
delivery
So I can know when it’s
going to be delivered
Scenario: Clicking a tracking URL
Given I am waiting for a delivery
And I received a confirmation
message
When I click the tracking URL
from the message
Then I should see a status of my
delivery

13. 13
Gherkin
Gherkin is plain-text English (or any other of the 60+
supported languages) with a little extra structure.
Is designed to be easy to learn by non-programmers, yet
structured enough to allow concise description of
examples to illustrate business rules in most real-world
domains.
In Gherkin each not-blank line should start with a keyword:
Feature, Scenario, Given, When, Then, And, Background, ...

14. 14
Gherkin examples

15. 15
Main benefits of BDD
●
Examples become unit tests and documentation
●
Scenarios become acceptance tests and documentation
●
Acceptance tests also become regression tests

16. 16
Benefits of BDD for developers
●
BDD will help you focus
●
BDD will give you confidence to refactor
●
BDD will help you better undersand the customers needs

17. 17
Benefits of BDD for Product Owners
●
BDD will give you a greater insight into the complexity of
what you’re asking for
●
BDD will give you transparency about what the team is
doing in each iteration
●
BDD will help your teams ship faster

18. 18
Benefits of BDD for Testers
●
BDD will mean you can find bugs even before they have
been written
●
BDD will give you the best automatic regression tests
●
BDD will free you to do interesting, creative, exploratory
testing

19. 19
BDD + TDD Cycle

20. 20
Testing Pyramid

21. 21
Use BDD in almost any language
●
Java
●
Concordion
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Easyb
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JDave
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JBehave
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Javascript
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Protractor
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Jasmine
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Cucumber
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Python
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Behave
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Groovy
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Cucumber
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PHP
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Kahlan
●
Behat
●
.NET
●
Concordion

22. 22
Questions ?