Testing, Learning and Professionalism — 20171214

(automatic) Testing
empresa, universitat, i professionalisme
David Ródenas — @drpicox

@drpicox
Qui soc?
• David Ródenas Picó
• Enginyer en Informàtica (pla del 91)
• Doctor en Informàtica
• Vicedegà del Col·legi d’Enginyers Informàtics
• Freelance Arquitecte Software i Formador
• Programador des dels 8 anys (el '86)
• Passat: professor universitari, empresari, becari, …
2

@drpicox 5
“The growth of Software Testing”- ACM June 1988 D.Gelperin, B.Hetzel
1957
1979
1983
1988
Debugging
Demonstration
Destruction
Evaluation
Prevention
mixing construction and debugging
making sure that software satisﬁes its speciﬁcation
detecting implementation faults
detecting requirements, design & implementation faults
preventing requirements, design & implementation faults

@drpicox 6
“The growth of Software Testing”- ACM June 1988 D.Gelperin, B.Hetzel
“

@drpicox 7
http://wiki.c2.com/?TenYearsOfTestDrivenDevelopment
1994
1999
2002
Beginning of new Era
xUnit
Extreme Programming
Framework Integrated Test
Test Driven Development
Ward Cunningham writes in one day a test runner
Kent Beck writes ﬁrst version of SUnit (Testing Framework)
“Extreme Programming Explained: Embrace Change” - Kent Beck
Ward Cunningham writes ﬁrst tool for test running
“Test Driven Development By Example” - Kent Beck
1989

@drpicox
Testing Tools
• NUnit, MSTest, …— C#
• FUnit, FRUIT, FortUnit, …— Fortran
• JUnit, FitNesse, Mockito, …— Java
• Jasmine, Mocha, QUnit, …— Javascript
• Unittest, py.test, Nose, …— Python
• MiniTest, Test::Unit, RSpec, … — Ruby
• …
• Cucumber, Selenium, SpecFlow, …— Scenario
8

@drpicox
Testing Tools
describe(‘calculator’, () => { 
it(‘should do sums’, () => {
let calculator = new Calculator();
calculator.input(2);
calculator.plus();
calculator.input(4);
calculator.equal();
let result = calculator.get();
expect(result).toBe(6);
});
…
});
9

@drpicox
Testing Tools
10
2,4,8 Rule Game
http://embed.plnkr.co/N0eGMg

@drpicox
Coding cost
12
+- +-
Think Write Debug
+-

@drpicox
Coding cost
13
Think
+-
• Surrounding code
• API for the new code
• Understand new features

@drpicox
Coding cost
14
Write
+-
• Faster typist speed is: 150 wpm
• Moderate typist speed is: 35 wpm
• 400 line code may contain 1000
words ~ 30 minutes

@drpicox
Coding cost
15
Debug
+-
• Even if everything works well, we
have to verify that it is true
• Navigate to affected point
• Make sure that everything works
as expected, each time
• If it fails, stop and start looking for
problems…

@drpicox
Coding cost
16
Debug
+-
¿How many debug cases
have you thrown away?

@drpicox
Coding cost
17
+- +-
Think Write Debug
+-

@drpicox
Coding cost
18
+- +-
Think Write Debug
+-

@drpicox
Coding cost
19
+- +-
Think Write Debug
+-

@drpicox
Why testing?
• Automatic testing saves time 
• Considers all features with all semantics
• Everything is debugged
• Does not throw away debug cases
• New features does not break old one
• Safe refactors to accommodate new changes
• More bald implementations 
• Developers(professionals) feel safer.
21

@drpicox
Types of bugs
23
Logic Wiring Visual

@drpicox
Types of bugs
24
Logic Wiring Visual
Detection
Diagnose
Correction

@drpicox
Types of bugs
25
Logic Wiring Visual
Detection HARD EASY TRIVIAL
Diagnose HARD MEDIUM EASY
Correction HARD MEDIUM EASY

@drpicox
Detection HARD MEDIUM EASY
Diagnose HARD MEDIUM EASY
Correction HARD MEDIUM EASY
Types of bugs
26
Logic Wiring Visual
It is hard!
Is it?

@drpicox
Types of testing
27
Logic
Wiring
Visual
#tests
whole system
subsystems
just classes
each takes

@drpicox
Types of testing
28
Logic
Wiring
Visual > 10s
< 1s
~1ms
few
many
lots
end-to-end
functional
unit
known as
whole system
subsystems
just classes
#testseach takes

@drpicox
Types of testing
29
Logic
Wiring
Visual > 10s
< 1s
~1ms
each takes
few
many
lots
end-to-end
functional
unit
known as
whole system
subsystems
just classes
acceptance testing
bdd
tdd
#tests

@drpicox
Types of testing
30
Logic
Wiring
Visualwhole system
subsystems
just classes
Unit
End-
-to-End
Functional
SoftwareEngineers
QAEngineers

@drpicox
Unit Testing
• It test the most dangerous kind of bugs
• It is easy to write
• It is fast to execute
• It is from engineers to engineers
• It focus into features details
31

@drpicox
Unit Testing
• It test the most dangerous kind of bugs → Solves them
• It is easy to write → Write tens in few minutes
• It is fast to execute → Development cycle of seconds
• It is from engineers to engineers → It is the doc
• It focus into features details → Solve fast ambiguity
• IT IS THE MOST POWERFUL TYPE OF TESTING
32

@drpicox
Unit Test Everything!
• Test coverage?
33

@drpicox
• Test coverage?
34
¿Are you sure that you want
to write a line of code that cannot be
justiﬁed with a test?
¿Do you want to
write useless code?
¿Do you want to
maintain more code
than necessary?
¿Do you want to
relay in your ability
to manual testing
all cases?

@drpicox
35
Serious Banking
http://embed.plnkr.co/veOMnl
🃏

@drpicox
Unit Test Everything?
36
Serious Banking
http://embed.plnkr.co/veOMnl
🃏
Sorry, not everything, we have frame problem.
(we can imagine inﬁnite stupid things that can go wrong)

@drpicox
TDD Rules
37
• Has anyone tried to write tests after write the code?

@drpicox
TDD Rules
1. You are not allowed to write any production code unless
it is to make a failing unit test pass.
2. You are not allowed to write any more of a unit test
than is sufﬁcient to fail; and compilation failures are
failures.
3. You are not allowed to write any more production code
than is sufﬁcient to pass the one failing unit test.
38
http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd

@drpicox
TDD Rules
39
• You can see it in the following Kata:
• The Bowling Game Kata

@drpicox
FIRST
• Fast
• Isolated/Independent: Arrange, Act, Assert
• Repeatable
• Self-Validating
• Thorough and Timely
40

@drpicox
Veriﬁcation
42
// Pre: 0 ≤ left ≤ right ≤ vec.length
function posMin(vec, left, right) {
let pos = left;
for (let i = left + 1; i <= right; i++) {
if (vec[i] < vec[pos]) pos = i;
}
return pos;
}
// Post: returns pos ∧
// ∧ left ≤ pos ≤ right ∧
// ∧ vec[pos] = min(vec[left … right])

@drpicox
Automatic Evaluation
43
$ cc my-solution.c -o my-solution
$ diff <(./my-solution < p1.in) p1.out 
$ diff <(./my-solution < p4.in) p4.out
$ cp my-solution.c /home/subject/e/h8463827.c

@drpicox
Patterns
• Abstraction
factory
• Builder
• Factory method
• Prototype
• Singleton
• Adapter
• Bridge
44
• Composite
• Decorator
• Facade
• Proxy
• Chain of
responsibility
• Command
• Interpreter
• Iterator
• Mediator
• Memento
• Observer
• State
• Strategy
• Template
method
• Visitor

@drpicox
Grasp
• Controller
• Creator
• High cohesion
• Indirection
• Expert
45
• Low coupling
• Polymorphism
• Protected variations
• Pure fabrications

@drpicox
Hello World
48
describe(‘hello world’, () => { 
it(‘it should say hi there!’, () => {
let helloWorld = new HelloWorld();
helloWorld.sayHello();
expect(???).toBe(‘hi there!’);
});
});
http://embed.plnkr.co/JxAOX7

ban
Singletons
Seriously
no buts
they lie
they
are evil
ARE GLOBALS!
i’ll got
zero in 1st course
if I've used them
also ban
class members

ban
Singletons
Seriously
no buts
they lie
they
are evil
ARE GLOBALS!
use singletons instead
(^ yes, lowercased s)
i’ll got
zero in 1st course
if I've used them
also ban
class members

@drpicox
Dependency Injection
function testCreditCardCharge() {
CreditCard c = new CreditCard(
"1234 5678 9012 3456", 5, 2008);
c.charge(100);
}
52
It gives as result: NullPointerException

@drpicox
Database.init();
CreditCardProcessor.init();
OfflineQueue.init();
"1234 5678 9012 3456", 5, 2008);
c.charge(100);
}
53
It works… but you loose 100$

@drpicox
Database db = new Database();
OfflineQueue q = new OfflineQueue(db);
CreditCardProcessor ccp =
new CreditCardProcessor(q);
"1234 5678 9012 3456", 5, 2008);
c.charge(ccp, 100);
}
54

@drpicox
"1234 5678 9012 3456", 5, 2008);
c.charge(ccp, 100);
}
55

@drpicox
"1234 5678 9012 3456", 5, 2008);
c.charge(ccp, 100);
}
56
Looks better, right? But you still loosing 100$.

@drpicox
CreditCardProcessorMock ccp =
new CreditCardProcessorMock();
"1234 5678 9012 3456", 5, 2008);
c.charge(ccp, 100);
assertTrue(ccp
.charged("1234 5678 9012 3456", 100));
}
57
Looks better!

@drpicox
• Is inversion of control for resolving dependencies.
• Your dependencies will explicitly be:
• given by constructor 
 
 
 
• setted after construction
58
class UserController {
constructor(userService) {
this.userService = userService;
}
}

@drpicox
59
Two piles
Pile of Objects
• Business logic
• This is why you write code
Pile of New Keywords
• Factories, Providers, …
• Build object graphs
• This is how you get the
code you write to work
together
new
new
new
new
new
new
new
new
new
new
new

@drpicox
60
describe(‘hello world’, () => { 
it(‘it should say hi there!’, () => {
let console = jasmine.createSpyObj(‘console’, [‘log’]);
let helloWorld = new HelloWorld(console);
helloWorld.sayHello();
expect(console.log).toHaveBeenCalledWith(‘hi there!’);
});
});
http://embed.plnkr.co/vZyo7u

@drpicox
Law of Demeter
• You only ask for objects which you directly need (operate
on)
• a.getX().getY()… is dead giveaway
• serviceLocator.getService() is breaking the Law of
Demeter
• Dependency Injection of the speciﬁc object you need.
Hollywood Principle.
61

@drpicox
How university can contribute?
• Write tests First!
• Create testing syllabus
• Get deeper in Cohesion
• Transmit: Professionalism require testing
62

Història
• 1945: O(1) ordinadors

Història
• 1960: O(100) ordinadors, O(1000) programadors
Enginyers
Cientíﬁcs
Matemàtics

Història
• 1960: O(100) ordinadors, O(1.000) programadors
• 1965: O(10.000) ordinadors, O(100.000) programadors
Enginyers + Cientíﬁcs + Matemàtics
Comptables
> Experienced Disciplined Professionals

Història
• 1970: O(100.000) ordinadors, O(1M) programadors
Tots els anteriors
Nois Joves
(50% dones)

Història
• 1970: O(100.000) ordinadors, O(1M) programadors
Des de 1970 el número de programadors  
es dobla cada 5 anys.

Història
• 1956: Fortran
• 1958: Lisp
• 1967: Simula '67 (primer OO)
• 1968: Dijkstra: programació estructura i GOTO
• 1970: Waterfall model (Req, Dis, Imp, Ver, Mant)
• 1972: C & Unix
• 1999: Extreme Programming
• 2001: Agile Manifesto
• 2002: TDD

@drpicox
This is real
• Toyota software has killed 89 people
• They have been ﬁned with $1.200.000.000
• They had to review 8.000.000 cars in US
76

@drpicox
Professionalisme
• We must have an ethic code to end discussions
• Medics have “Hippocratic Oath”
• We have testing
77

@drpicox
Sumary
• Testing saves development time
• Focus in Unit Test  
(acceptance testing is also amazing)
• Tests to show that your code is what you need
• Make dependencies explicit
79

@drpicox
Sumary
• Testing saves our professional reputation
80

@drpicox
Sumary
• and of course:
81
Write tests First!

@drpicox
Bibliography
82
• “The growth of Software Testing”- ACM June 1988 D.Gelperin, B.Hetzel
• http://wiki.c2.com/?TenYearsOfTestDrivenDevelopment
• https://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882
• https://www.amazon.com/Clean-Coder-Conduct-Professional-Programmers/dp/0137081073
• http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd
• http://butunclebob.com/ArticleS.UncleBob.SingletonVsJustCreateOne
• http://misko.hevery.com/2008/11/17/uniﬁed-theory-of-bugs/
• http://misko.hevery.com/2008/08/25/root-cause-of-singletons/
• http://misko.hevery.com/2008/08/17/singletons-are-pathological-liars/
• http://misko.hevery.com/code-reviewers-guide/
• http://misko.hevery.com/2008/10/21/dependency-injection-myth-reference-passing
• http://misko.hevery.com/2008/11/11/clean-code-talks-dependency-injection/
• http://butunclebob.com/
• http://misko.hevery.com/
• plnkr.co/users/drpicox

@drpicox
Thanks!
84
David Ródenas — @drpicox

Testing, Learning and Professionalism — 20171214

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Testing, Learning and Professionalism — 20171214