How can I refactor legacy Java code and implement unit testing?

How can I refactor legacy Java code and implement unit testing?

Refactoring legacy Java code involves improving its structure without changing its behavior. Start by identifying code smells, then gradually refactor methods and classes. For unit testing, use JUnit to create tests for your refactored code.

What are some common code smells I should look for?

Common code smells include duplicated code, long methods, large classes, and excessive comments. These indicate areas that may need refactoring.

Can you give me an example of a simple refactor?

Sure! If you have a method that calculates the total price with tax, you might extract the tax calculation into its own method to improve readability.

How do I write a unit test for that method?

You can use JUnit to write a test case. Create a test class, use the @Test annotation, and assert the expected value against the actual output of your method.

What if my legacy code is tightly coupled?

If your code is tightly coupled, consider using dependency injection to decouple components. This will make it easier to test and refactor.