Tag Archives: Three

Legacy Coderetreat: Episode 12 – Unit Testing on Legacy Code – Code Cast

Unit Testing on Legacy Code – code cast

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

Code Cast

This is a code cast in Java.

In the previous episodes we reach the moment when we extracted one simple class. We used the The Rule of Three and pure functions. This newly extracted class is covered with characterization tests. But that is not enough, we want to continue adding other types of tests to understand the system better.

This is why during this episode you will see how to add unit tests to code extracted from a legacy code class. These tests have a small granularity level than the characterization tests we already have. This is the moment to dive more into details.

See this video to understand how you can document the current state of the system, by unit testing on legacy code.

Read here more about this concept in my blog post.

Legacy Coderetreat: Episode 11 – Extract Class – Code Cast

Extract Class – code cast

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

Code Cast

This is a code cast in Java.

In the previous episodes we restructured some parts of the code base. We also extracted pure functions and applied The Rule of Three when restructuring the code.

Because we have extracted some pure functions, now we need to think if those pure functions belong to new classes. So we structure the functions in a way that they belong together from the point of view of their responsibilities. After structuring the functions we extract the class.

Learn from this video how to extract a class in legacy code in such a way that you do not introduce side-effects to the existing behaviour.

Read here more about this concept in my blog post.

Legacy Coderetreat: Episode 10 – Refactoring the Rule of Three – Code Cast

Refactoring the Rule of Three – code cast

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

Code Cast

This is a code cast in Java.

When refactoring legacy code we need to make sure the structures we extract have a correct meaning. This is why The Rule of Three is very useful: extract to a new structure only when you find an identical duplication three times. Usually we do not have identical duplication, so in that case we need to make the duplication clear, check that it exists three times and only after that perform the extraction.

This code cast will show you also when it is not a good idea to extract a new variable, even if you see it duplicated many times. This is a mechanical kind of refactoring, but reasoning is very important even when we want to get fast by getting mechanical refactorings into our tool bag.

Read here more about this concept in my blog post.

Legacy Coderetreat: Part 11 – Refactoring Rule of Three

Rule of Three

Blog post series

This blog post is part of a series about legacy coderetreat and legacy code techniques you can apply during your work. Please click to see more sessions about legacy code.

Purpose

The rule of three says:

Extract duplication only when you see it the third time.

This concept is extremely useful when you want to improve legacy code, refactor in the TDD cycle or just improve existing code that is covered by tests.

The Rule of Three brings higher coherence and more clarity to the system, because the duplicated code starts to be moved into specialized areas. In this way we optimize the code base for changeability.

The Rule of Three prevents from prematurely extracting possible duplication and defers the duplication minimization until we have enough proof.

minimize-duplication

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