Entries Tagged as 'OO'

Static Methods are Death to Testability

December 15th, 2008 · 55 Comments

by Miško Hevery Recently many of you, after reading Guide to Testability, wrote to telling me there is nothing wrong with static methods. After all what can be easier to test than Math.abs()! And Math.abs() is static method! If abs() was on instance method, one would have to instantiate the object first, and that may prove [...]

Tags: OO · Rant · Testability

Testability Explorer: Measuring Testability

October 21st, 2008 · 4 Comments

Testability Explorer: Using Byte-Code Analysis to Engineer Lasting Social Changes in an Organization’s Software Development Process. (Or How to Get Developers to Write Testable Code) Presented at 2008 OOPSLA by Miško Hevery a Best Practices Coach @ Google Abstract Testability Explorer is an open-source tool that identifies hard-to-test Java code. Testability Explorer provides a repeatable [...]

Tags: Advice · OO · Testability · Testability Explorer

Dependency Injection Myth: Reference Passing

October 21st, 2008 · 31 Comments

by Miško Hevery After reading the article on Singletons (the design anti-pattern) and how they are really global variables and dependency injection suggestion to simply pass in the reference to the singleton in a constructor (instead of looking them up in global state), many people incorrectly concluded that now they will have to pass the [...]

Tags: Advice · OO · Testability

Where Have all the “new” Operators Gone?

September 10th, 2008 · 7 Comments

(the other title: Your Application has a Wiring Problem) In My main() Method Is Better Than Yours we looked into what a main() method should look like. There we introduced a clear separation between (1) the responsibility of constructing the object graph and (2) the responsibility of running the application. The reason that this separation [...]

Tags: Advice · OO · Testability

Where Have All the Singletons Gone?

August 21st, 2008 · 24 Comments

by Miško Hevery In Singletons are Pathological Liars we discussed the problems of having singletons in your code. Let’s build on that and answer the question “If I don’t have singletons how do I ensure there is only one instance of X and how do I get X to all of the places it is [...]

Tags: Advice · OO · Rant · Testability

Singletons are Pathological Liars

August 17th, 2008 · 77 Comments

by Miško Hevery So you join a new project, which has an extensive mature code base. Your new lead asks you to implement a new feature, and, as a good developer, you start by writing a test. But since you are new to the project, you do a lot of exploratory “What happens if I [...]

Tags: Advice · OO · Rant · Testability

Procedural Language Eliminated GOTOs; OO Eliminated IFs

August 14th, 2008 · 7 Comments

by Miško Hevery Procedural languages allowed us to remove GOTOs in our code. I would like to think that OO languages allow us to remove IFs (conditionals). I know you can’t remove of all the IFs, but it is interesting just how many IFs you can remove in an application. You can’t remove these IFs: [...]

Tags: Advice · OO · Testability · Uncategorized

Circular Dependency in constructors and Dependency Injection

August 1st, 2008 · 27 Comments

by Miško Hevery So you discovered dependency injection and GUICE and you are happily refactoring and writing new tests for you code until you come across this circular reference. class A { final B b; A(B b){ this.b = b; } } class B { final A a; B(){ this.a = new A(this); } } [...]

Tags: Advice · OO · Testability