Is this how you hate unit testing?

www.odd-e.com

I hate unit testing!!!

Friday, 9 December, 11

Who am I?

• Name: Steven Mak• Agile Coach at Odd-e• Lives in Hong Kong• Agile, TDD Coaching• I love coding - Java, C/C++,

PHP, Perl, and some weird ones

• I speak English, Cantonese, and Mandarin

本故事純屬虛構如有雷同實屬巧合

I HATE UNIT TESTING!

•Doesn’t catch many bugs•Still need to do integration tests•Waste time

Need to test at integration level anyway?

Is this what you mean by integration testing?

How many tests do you need to cover through system level tests?

10states

5 interactions 5 interactions

5 interactions

Adapted from: http://www.renaissancesoftware.net/files/sglon/LondonScrumGathering-v1r0.key.pdf

• It would take 1000 (or more) tests to this simple system!• System Level Tests just cannot be thorough

The down side• Tons of them to write• False sense of security• Integration tests are slow• Hard to diagnose• Brittle

- one change would trigger many test failures

Test Automation Pyramid

You are going to need some integration tests, but not in the way you do like unit tests.

Write good focused unit tests

• Don’t test the platform.• When writing a single object to test with other

collaborating objects, use interfaces for those other points. Interfaces are not the actual collaborating object.

• Leverage the interfaces so you don’t need to actually test the other objects.

• Test the single object to speak to itself, i.e. State Tests

• Create your focused Collaboration and Contract Tests.

http://b-speaking.blogspot.com/search/label/integration%20tests

Collaboration and Contract Tests

• Collaboration tests:- Do I ask the collaborators the right questions?- Can I handle the collaborators’ responses?

• Contract tests:- Can the interface accept the question being asked of it?- Can the interface supply the responses expected?

Example:

@Testpublic void with_arguments(){! MyCollaborator c = mock(MyCollaborator.class);! when(c.compareTo("Test")).thenReturn(1);! assertEquals(1,a.doSomethingElse("Test"));}

We are assuming that compareTo() would return 1 if we pass in “Test”

@Testpublic void compareToShouldReturnOne(){! ! MyCollaborator c = new MyCollaborator();! ! assertEquals(1,c.compareTo("Test"));}

We write a test for the real MyCollaborator.compareTo()

Contract tests are usually slow but tend to be stable. Often running just once a day is plenty

Refactoring?

Code smells!

Code stinks!

It’s no fun writing unit test if you don’t spend time refactoring

Why? How?

amount of bad

amount of code

smells

time spend on

bug fixing

motivation

developers

quick hacks

opportunity for

# of bugs

indicates

refactoring

Refactoring visualized

Original program:

Making changes:

More changes:

Without refactoring:

Original program:

Making changes:

More changes:

Original program:

Making changes:

More changes:

Cost of change increases rapidly!

Original program:

Making changes:

More changes:

With refactoring:

Original program:

Making changes:

More changes:

With refactoring:

Small change

Original program:

Making changes:

More changes:

With refactoring:

Small change

Original program:

Making changes:

More changes:

With refactoring:

Small change

Refactor

Original program:

Making changes:

More changes:

With refactoring:

Small change

Refactor

Original program:

Making changes:

More changes:

With refactoring:

Small change

Refactor

Cost of change not increases

Refactoring based on unit testing

What to refactor?

Beware of blocking

• Individual Code Ownership?• Branching for long time?• Deadline pressure?

- Refactoring makes your code base easier to work on

Time consuming?

Too busy fire fighting, but no time to write tests?

Speculate Code Test Debug

Sustainability

Traditional development

Time vs

Sustainability

Time developers do not notice nor plan for

Time vs

Sustainability

Time developers do not notice nor plan for

Time vs

Test-driven development

Speculate Test and Code Debug

Sustainability

Time vs

Test-driven development

Speculate Test and Code Debug

Feels slower

We are tired of delivering craps

Do you have confidence with your work before you deliver it?

Edsger Dijkstra“Those who want really reliable software will discover that they must find means of avoiding the majority of bugs to start with, and as a result, the programming process will become cheaper. If you want more effective programmers, you will discover that they should not waste their time debugging, they should not introduce the bugs to start with.”

TDD Cycle

Implement

Design

• Short• Rhythmic• Incremental • Design-focused• Disciplined

Oh, Our code was there already

1. Identify change point2. Find test points3. Break dependencies4. Write tests5. Make changes and refactor

It is always harder to write unit tests after we wrote the code

Our code is too simple, so we don’t need unit testing

Our code is too complicated, so writing unit tests is too difficult

We don’t have problems at unit level

Tests you write after the fact are Defense or Justification

• Test later = Test never• After-the-fact tests are written by someone

who is already vested in the code and already knows how the problem was solved

• There’s just no way those tests can be anywhere near as incisive as tests written first

• If you write the unit test after the fact, you are not going to catch many bugs.

Unit test is not just about testing

Look at the design through unit tests

Modularity == Testability

Focus on tests first ensures modularity and other good design principles

Design from the perspective of userather than implementation

• Debug-later-programming don’t consider testability in the first place• TDD guarantees testability, while you still need to know good design

principles• Unit tests give you a safety net to try different design

It is always harder to write unit tests after we wrote the code

When you find it hard to write unit tests...

• Instantiating class instance that is hard to setup?- What about using Factories?- Have you think about Dependency Injection?

• Long methods?- Does it have more than one responsibilities?

• Bare classes?- Why not provide abstract base classes to support better mocking?- Why clients need to know everything from this base class?

• Interface Segregation Principle

• Confidence and trust in the code

- Treading the happy path

- “If it doesn’t have to work, I can get it done a lot faster!”

- “Cost of bug fixing is lower if it is found earlier”

• Encourages good design

- Clean it up later

- Experimenting different design

• Integration Testing

- Making assumptions explicit

TDD, The Professional Option

Resources

Agile Tour ShenZhen• Tencent Building, Shenzhen (騰訊大廈）

- 20 Nov 2011- Tencent Building, Kejizhongyi Avenue, Hi-techPark,Nanshan

District,Shenzhen.- 深圳市南山区科技园科技中一路腾讯大厦，深南大道北侧

• http://www.agiletour.cn• Contact: steven@odd-e.com

I want to organise a group in Hong Kong!

http://tinyurl.com/HKALSDN

Is this how you hate unit testing?

Technology

Unit 2 unit testing

Unit Testing

Unit testing Unit testing TDD with JUnit. Unit Testing Unit testing with JUnit 2 Testing concepts Unit testing Testing tools JUnit Practical use of tools

Unit Testing Code - Information and Computer Sciencecis110/current/lectures/cis110JUnit.pdf · Unit Testing Code. Testing a unit of code. Testing a unit of code. Identify: 1. INPUT,

Is the ‘hate’ in hate speech the ‘hate’ in hate crime

Approach of Unit testing with the help of JUnit Unit testing with JUnit2 Unit Testing Testing concepts Unit testing Testing tools JUnit Practical use

Practical Unit Testing jUnit - University of Michiganweb.eecs.umich.edu/~aprakash/eecs282/lectures/08-unit-testing.pdfPractical Unit Testing jUnit ... •jUnit is a standard unit testing

Ins & Outs of Unit Testing All About Unit Testing

Testing for people who hate testing

Developer testing - Love it or hate it (in Swedish)

Mental/Emotional Health Unit Part 3...Saying, "It's gonna be alright." 'Cause the players gonna play, play, play, play, play And the haters gonna hate, hate, hate, hate, hate Baby,

How I Learned to Love and Hate Web-Testing

Mutation Testing€¦ · • Unit Testing + Code Coverage. Unit Testing. Unit Testing int sum(int a, int b) { return a + b; } Unit Testing int sum(int a, int b) { return a + b; }

Unit Testing Testing - Drexel CCIspiros/teaching/SE320/slides/unit-testing-tools.pdfjUnit • Testing harness for Java ... Unit Testing C: Check • Check is a unit testing framework,

SOA Unit Testing - Oracle · Agenda What is Unit Testing Service Unit Testing SOA Unit Testing Techniques and Tools Demo Challenges Questions?

Unit Testing - Technische Universität München · Unit Testing Bernd Bruegge ... •Polymorphism testing Next lecture •Integration testing •Testing strategy ... Subsystem Tested

Software Testing Methodologies Unit II - khitguntur.ac.in testing Unit II.pdf · Software Testing Methodologies Unit II Page 1 UNIT –II TRANSACTION FLOW TESTING (1) Transaction