培育软件的可测试性

CultivateSoftware Testability Juven Xu Agile Tour Shanghai 2011

Juven Xu 许晓 Twitter: @juvenxu Weibo: @Juvenxu juvenshun@gmail.comhttp://www.juvenxu.com/

Why we discuss testability here?

Why we discuss testability here?Because testing is expensive.

Why we discuss testability here?Because testing is expensive.Because we want more tests.

Why we discuss testability here?Because testing is expensive.Because we want more tests.Because testable software tends to be well designed.

Why we discuss testability here?Because testing is expensive.Because we want more tests.Because testable software tends to be well designed.Because it’s a bond between developers and testers.

Higher testability, higher quality

Code Example

public class Emailer { private SpellChecker spellChecker; public Emailer() { this.spellChecker = new EnglishSpellChecker(); } ...} Is there a way to test the interaction between Emailer and SpellChecker?

public class Emailer { private SpellChecker spellChecker; public Emailer(SpellChecker spellChecker) { this.spellChecker = spellChecker; } ...}

public class Emailer { private SpellChecker spellChecker; public Emailer(SpellChecker spellChecker) { this.spellChecker = spellChecker; } ... }public class EmailerTest { public class MockSpellChecker implements SpellChecker { @Test private boolean didCheckSpelling = false; public final void ensureSpellingWasChecked() { MockSpellChecker mock = new MockSpellChecker(); public boolean check(String text) { didCheckSpelling = true; new Emailer(mock).send(“Hello!”); return true; assert mock.verifyDidCheckSpelling() } : “failed to check spelling”; } public boolean verifyDidCheckSpelling() {} return didCheckSpelling; } }

What we have done for testability?Allowed the test to control the construction of Emailer.Allowed the test to observe the behavior of the Emailer.

IEEE deﬁnes testability as:“The degree to which a system or componentfacilitates the establishment of test criteria andthe performance of tests to determine weatherthese criteria have been met.”

IEEE deﬁnes testability as:“The degree to which a system or componentfacilitates the establishment of test criteria andthe performance of tests to determine weatherthese criteria have been met.” “But what the hell does this mean?”

In stead, can we think test as:1. Prepare the software to a state ready to be tested.2. Input test data.3. Observe the output.4. Compare the actual output to the expected output.

Then, we deﬁne testability as: Control Visibility Knowledge

Control,Visibility, and Knowledge

I see what is testability and why it matters, but how to cultivate it?

• Use Dependency Injection• Follow Single Responsibility Principle• Log Carefully• Manage Conﬁguration• Prefer Conventional Interface

“Most of the critical problemswith integration can be avoided if framework designers keep one fundamental principle in mind: testability” -- Dhanji R. Prasanna

DI is about building the Object Graph.

Dependency Injection• It gives you control• It provides you visibility• It implied good design

Test It!

Test It!Single Responsibility Principle

Logging for Visibility

Logging for Visibility• Don’t log too less, don’t log too much• What to log• Log Level

Manage the Conﬁguration• Separate conﬁguration from runtime.• Keep it simple.• Make it easy to be changed.

<?xml version=”1.0” encoding=”UTF-8”> <web-app> <servlet> <servlet-name>awesome_servlet</servlet-name> <description>Am I Awesome?</description> <servlet-class>com.awesome.AwesomeServlet</servlet-class> <init-param> <param-name>awesome-level</param-name> <param-value>super</param-value> </init-param> </servlet> <servlet-mapping> ... </web-app></xml> Looks familiar?

Prefer Conventional Interface• Plain Text over Binary• HTTP over SOAP• Convention over Conﬁguration

References• Marc McDonald (2007). The Practical Guide to Defect Prevention. Microsoft Press• Bret Pettichord (2002). “Design for Testability”• Lesse Koskela (2007). Test Driven:TDD and Acceptance TDD for Java Developers. Manning Publications• Dhanji R. Prasanna (2009). Dependency Injection, Manning Publications• Jez Humble (2010). Continuous Delivery: Reliable Software Releases through Build,Test, and deployment Automation, Addison-Wesley Professional• Andrew Hunt (1999). The Pragmatic Programmer: From Journeyman to Master, Addison-Wesley Professional

http://www.juvenxu.com	5050
http://zhuaxia.com	15
http://www.zhuaxia.com	12
http://ww.juvenxu.com	12
http://cache.baidu.com	5
http://xianguo.com	5
http://98.130.162.53	3
http://us-w1.rockmelt.com	2
http://mvnbook.juvenxu.com	2
http://www.juvenxu.com&_=1328330573218 HTTP	1
http://a0.twimg.com	1
http://www.juvenxu.com.	1
http://snapshot.soso.com	1

培育软件的可测试性

by agiletourchina on Dec 22, 2011

Accessibility

Categories

Tags

Upload Details

Usage Rights

13 Embeds 5,110

Statistics

培育软件的可测试性 — Presentation Transcript