The Clean Code Talks concentrating on writing testable code. In his talk, Unit Testing, Miško Hevery explains unit testing and makes a case for unit tests.
In his talk, Don’t look for things, Miško Hevery provides a practical guide to the Principle of Least Knowledge (aka Law of Demeter, aka Don’t Ask, Tell)
In his talk, Global State and Singletons, Miško Hevery explains why global state leads to bad APIs and difficult to test code.
In his talk, Inheritance, Polymorphism, & Testing, Miško Hevery presents his premise that most if statements can be replaced with polymorphism and explains why one would want to do so.
In his talk, GuiceBerry, Luiz-Otavio Zorzella makes a case for using dependency injection in your test code