Dependency injection with Spring allows code to be decoupled from implementations by injecting dependencies. This makes code easier to test by allowing real objects to be substituted with mocks. The document demonstrates using Spring to inject different DAO implementations into a service class, and shows how this improves testability by allowing tests to inject mock DAOs. The conclusion is that Spring dependency injection enables independence and high testability through easy substitution of real objects with mocks.

1. Dependency Injection and Testing with the Spring framework
Leonardo Borges ­ www.leonardoborges.com

2. Dependency Injection and Testing with the Spring framework
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Why dependency injection?
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It frees your code of knowing about the underlying
implementation
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Eliminates the necessity of lookup codes, thus
saving development time
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Eases the testing environment

3. Dependency Injection and Testing with the Spring framework
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A first example

4. Dependency Injection and Testing with the Spring framework
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Testing the Service class

5. Dependency Injection and Testing with the Spring framework
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Great! A JDBC DAO! But I was planning to
use Hibernate!
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Problem
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The service object knows the DAO's implementation
class
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Solution
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Make the DAO classes implement an interface

6. Dependency Injection and Testing with the Spring framework
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The new DAO classes

7. Dependency Injection and Testing with the Spring framework
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But to achieve independency, we need to
change the service class

8. Dependency Injection and Testing with the Spring framework
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Dependency Injection kicks in

9. Dependency Injection and Testing with the Spring framework
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It's all about context

10. Dependency Injection and Testing with the Spring framework
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Testing the new Service class

11. Dependency Injection and Testing with the Spring framework
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It's all about [test] context

12. Dependency Injection and Testing with the Spring framework
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Results from testing the new Service class

13. Dependency Injection and Testing with the Spring framework
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Conclusions
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With dependency injection and spring, you can
achieve a great level of independence while
keeping your code highly testable trough the easy
substitution of your real objects by mocks.

14. Dependency Injection and Testing with the Spring framework
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Further Resources
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www.springframework.org
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www.leonardoborges.com