Monthly Archives: February 2015

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Legacy Coderetreat: Part 13 – Unit Testing on Legacy Code

Unit Testing on Legacy Code

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

In the previous episode post we extracted a class. The code we just extracted is tested at this moment only with System Tests. Now it’s the time to start writing unit tests, considering that we already have some system tests in place.

Unit Testing on Legacy Code

Unit Testing on Legacy Code

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Legacy Coderetreat: Part 12 – Extract class

Extract Class

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

When working with existing code we need to look at the responsibilities of existing classes. If one class is too big, we need to extract new classes from that initial class. A class too big means that it’s not respecting the Single Responsibility Principle.

Extract Class

Extract Class

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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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Legacy Coderetreat: Part 10 – Extract pure functions

Extract Pure Functions

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

We have some class that is very big. We want to divide the existing code into more methods and classes so that we have in the end some code that is easier to understand. If the methods are small, they are easy to change. In the same time the code would respect the Single Responsibility Principle. We optimize our software for changeability. In the following we will see how we can extract pure functions to achieve that.

Pure functions

Pure functions

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