Introduction to Software Testing

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Testing
A brief introduction

Main concepts

“I get paid for code that works, not for
tests, so my philosophy is to test as little
as possible to reach a given level o...

No silver bullets

What is testing about?

Getting feedback,
as much frequent as we can

the sooner, the better

TAXONOMY

Taxonomy
Scope
Unit
Integration
System
Visibillity
Black box
White box
Intention
Acceptance
Functional
Non Functional
…
Te...

Visibillity
Black
box
White
box
System
Integration
Unit
Intention
Acceptance
Functional
Non
Functional
Technique
Dynamic
S...

Scope
Database
PORT1 PORT2
ADAPTER1

Unittest
Database

Dependency injection
•Dependency:
A depends on B when A needs B to do
its job.
•Injection:
Object which uses A tells A who...

Dependency injection
• Separate business logic from creation logic
• Avoid use of new for service objects.
• Value objects...

Dependency injection
public UserService(UserValidator userValidator, UserDao userDao) {
this.userValidator = userValidator...

Dependency injection
public UserService(UserValidator userValidator, UserDao userDao) {
this.userValidator = userValidator...

Test doubles
•Fake
•Stub
•Spy
•Mock

Test doubles (Fake)
public UserDaoFake implements UserDao {
@Override
public User create(User user) {
return new User(...)...

Test doubles (Stub)
UserValidator validatorMock = mock(UserValidator.class);
stub(validatorMock.validate(any(User.class)))...

Test doubles (Spy)
Spies are objects that also record some
information based on how they were called
var validatorSpy = Si...

Test doubles (Spy)
Spies are objects that also record some
information based on how they were called
var validatorSpy = Si...

Test doubles (Mocks)
UserValidator validatorMock = mock(UserValidator.class);
when(validatorMock.validate(any(User.class))...

Integrationtestwhichwanttobeunittests
Database

FIRST(IT)
• Fast
Hundreds or thousands per second
• Isolates
Failure reasons become obvious
• Repeatable
In any order, any...

Integrationtestwhichworkswithexternalsystem
Database

IntegrationtestwhichusestheUI
Database

Systemtest
Database

Who, when and where run the tests?
• Unit
• Owner: developer
• When: after every change
• Where: every computer
• Integrat...

STRATEGIES

Static evaluation
•Informal review
•Formal review (inspection)
• Checklists
• Sucessive abstraction
•Walkthrough

Dynamic evaluation
• White box
• Path Coverage
• Statement Coverage
• Condition Coverage
• Function Coverage
• Black box
•...

White box (*-coverage)
1. Get flow diagram of the SUT
2. Calculate cyclomatic complexity
3. Determine a data set which for...

White box (*-coverage)
1. Get flow diagram of the SUT
2. Calculate cyclomatic complexity
3. Determine a data set which for...

White box (*-coverage)
1. Get flow diagram of the SUT
2. Calculate cyclomatic complexity
3. Determine a data set which for...

Black box (partitioning)
1. Identify equivalence classes
2. Select dataset:
1. Assign a unique value for every class
2. Se...

Black box (partitioning)
Register
Username*
Password (6-10 chars including numbers)

Black box (partitioning)
Register
Username*
Password (6-10 chars including numbers)
Username Password
U1: myNick P1: p4ssw...

Black box (partitioning)
Register
Username*
Password (6-10 chars including numbers)
Username Password
U1: myNick P1: p4ssw...

AUTOMATIC TESTING

4 phases-tests
1.Set Up
2.Exercise
3.Verify
4.TearDown

Testing frameworks families
• X-Unit
• @Before(Class)
• @Test
• @After(Class)
• Rspec
• describe
• beforeEach
• it
• after...

XUnit
@Before
public void setUp() {
this.userValidator = mock(UserValidator.class);
this.userDao = mock(UserDao.class);
th...

Rspec (suite per class)
describe('UserService test suite:', function(){
beforeEach(function(){
// setup the SUT
})
it('whe...

Rspec (suite per setup)
describe('UserService test suite:', function(){
describe("when create a valid user ", function() {...

BDD (specification)
Feature: User registration
Scenario: User tries to register sending valid data so the system will crea...

BDD(implementation)
@given("the user has introduced (w)+ and (w)+ into the registration form")
public void populateForm(St...

TESTABLE DESIGN

Non-Testable design smells
(by Misko Hevery*)
•Constructors does Real Work
•Digging into collaborators
•Brittle Global Sta...

Constructors does Real Work
• new keyword in a constructor or at field declaration
• Static method calls in a constructor ...

Digging into collaborators
• Objects are passed in but never used directly
(only used to get access to other objects)
• La...

Brittle Global State & Singletons
• Adding or using singletons
• Adding or using static fields or static
methods
• Adding ...

Class Does Too Much Work
• Summing up what the class does includes the
word “and”
• Class would be challenging for new tea...

Questions & Stupid questions
• ¿Where I place my tests?
• ¿Who tests the classes which test our classes?
• ¿Could you be a...

¿Where I place my tests?
• Unit tests:
• Test Class per Class
• Test Class per SetUp (useful in Xunit frameworks)
• Import...

¿Where I place my tests?
Java Project (Test Class per Class)
MyProject/
src/
main/
java/
com.groupId.artifactId.MyClass.ja...

¿Where I place my tests?
Android Project
MyProject/
AndroidManifest.xml
res/
... (resources for main application)
src/
......

¿Who tests the classes which
test our classes?
• Exactly, this is why it’s so important our tests follow
KISS

¿Couldyoube able to rewrite the codeonly
reading the tests definitions?
• Tests (specially Black Box tests) should tell us...

IspendmoretimewritingcodetosetupmySUTthan
writingthetest,howdo you solveit?
• Read about Fixtures (Xunit Patterns is a
goo...

Iduplicatetoomuchcodeonobjectscreation,mocks
definitionandassertion…
• Writing a lot of code to initialize value objects?
...

¿What is the minimum coverage
should I expect for my code?
• It depends on the project.
• “… test as little as possible to...

I’ve never write a test ¿where can I
start?
Database
PORT1 PORT2
ADAPTER1
I’ll bet you a
beer , you
called it *Util…

My code is not testable at all,
¿what can I do?
• First of all, go to http://refactoring.com/
• I suggest:
1. Add integrat...

Recommended reading
• Growing Object Oriented Software Guided Tests
• Xunit Patterns
• Continuous delivery
• Hexagonal Arc...

Place your question here!

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