Continuous refactoring is a skill that every Certified Scrum Professional for Developers (CSP-D) should have in their arsenal. Legacy systems, or older technologies that are often resistant to change, often benefit from this approach.
Continuous refactoring means making small, incremental changes to the source code, design, or database to improve how they function. The goal is to enhance the system’s functionality, performance, reliability, and readability without changing its exterior behavior.
The Importance of Continuous Refactoring in Legacy Systems:
Legacy systems often present a challenge for developers as they usually come with years, if not decades, of built-up technical debt. Refactoring helps in identifying and removing the “band-aid” solutions that have been applied over the years. It can also unearth hidden dependencies, outdated libraries, inefficient practices, and hard-coded business rules that are no longer relevant.
Steps for Continuous Refactoring:
- Understanding the Code:
The very first step is to understand what the code is trying to achieve. A good practice is to document the flow and the functionality of the code, which would make the refactoring process easier.
- Identifying Code Smells:
Code smells are signs that your code might need refactoring. These could be duplicated code, long methods, long class, or large switch statements.
- Prioritizing Smells:
Since refactoring is a time-consuming process, prioritize the code smells based on their impact on business functionality and performance of code.
- Automated Tests:
It’s crucial to write a suite of automated tests for every code you plan to refactor. These tests will ensure that functionality remains unchanged after refactoring.
- Refactoring:
Now comes the actual refactoring, like Red-Green Refactor: start by making the test cases go red, refactor the code and make the test cases go green again. Always aim to refactor a bit at a time; iterative refactoring makes the process manageable and reduces risks.
- Code Review and Testing:
After refactoring, review the code for possible bugs and run the test cases again to ensure functionality has not been impacted.
Refactoring Techniques:
Here are a few commonly used refactoring techniques:
- Extract Method: This technique is used if a code segment can be grouped together. The method creates a new method and moves the grouped code into it.
- Inline Method: This technique is used if the body of a method is as clear as its name. The method moves the method’s body into the body of its callers and removes the method.
- Replace Magic Number with Symbolic Constant: This technique replaces obscure literal constants with named constants.
- Decompose Conditional: This technique decomposes the complicated parts of the condition and the conditional itself separately.
- Replace nested Conditional with Guard Clauses: A method has conditional code that can be clarified with a guard clause, replace the conditional with a guard clause.
Conclusion:
Refactoring is not a one-time process for legacy systems; it should be a regular part of your development cycle. The goal is not to make the system perfect but to continuously improve it and reduce its complexity. By following a disciplined approach to identifying, prioritizing, and addressing code smells, developers can enhance the maintainability and longevity of legacy systems, making them more agile and responsive to changed business needs. So, make continuous refactoring a part of your CSP-D toolkit.
Practice Test
True or False: Refactoring a legacy system is the process of changing the internal structure of the software without affecting its external behavior.
- True
- False
Answer: True
Explanation: Refactoring involves cleaning up and simplifying the design of existing code, without changing its functionality. This is done to improve system readability and reduce its complexity.
In Scrum development, when should refactoring be practiced?
- A. Only when a change is needed
- B. As a continuous process throughout the project lifecycle
- C. Only at the start of the project
- D. Only at the end of the project
Answer: B. As a continuous process throughout the project lifecycle
Explanation: Continuous refactoring helps in maintaining the clarity of the code and minimizing the technical debt.
Which of the below is not a benefit of continuously refactoring a legacy system?
- A. Improved code readability
- B. Reduced debug time
- C. Increased technical debt
- D. Reduced complexity
Answer: C. Increased technical debt
Explanation: Continuous refactoring helps in managing and reducing technical debt, rather than increasing it.
True or False: A legacy system should only be refactored if there is a bug or issue with the current functionality.
- True
- False
Answer: False
Explanation: Refactoring a legacy system isn’t only about resolving issues but as a form of proactive measure to improve the software structure and performance, and reduce future issues.
Refactoring a legacy system poses risks.
- A. True
- B. False
Answer: A. True
Explanation: Refactoring, although beneficial, can pose risks such as the introduction of new bugs. Testing and proper implementation can mitigate these risks.
In order to practice continuous refactoring, comprehensive tests must be in place.
- A. True
- B. False
Answer: A. True
Explanation: Tests ensure that refactoring does not introduce new bugs into the system and ensures that the functionality remains the same.
Refactoring should be a separate activity and not a part of the development process.
- A. True
- B. False
Answer: B. False
Explanation: Refactoring should be integrated into the development process and should be performed continuously to keep the code clean and manageable.
During refactoring, new functionalities should be added.
- A. True
- B. False
Answer: B. False
Explanation: The purpose of refactoring is to improve the internal structure of the software, not to add new functionalities.
The primary purpose of refactoring is to improve performance.
- A. True
- B. False
Answer: B. False
Explanation: Although refactoring can result in performance improvements, its primary purposes are to improve software readability and reduce its complexity.
Maintaining a legacy system without refactoring can result in a higher cost over time.
- A. True
- B. False
Answer: A. True
Explanation: Without continuous refactoring, systems become harder to maintain, leading to high technical debt, which in turn results in higher cost over time.
Interview Questions
What does refactoring mean in the context of Software Development?
Refactoring in software development refers to the process of restructuring existing computer code without changing its external behavioral output, with the aim to improve the nonfunctional attributes of the software.
What is the purpose of adopting a continuous refactoring approach on a legacy system in Scrum?
The purpose of adopting a continuous refactoring approach on a legacy system in Scrum is to continually improve the code base, making it easier to understand, cheaper, and faster to modify without adding new functionality.
Why is continuous refactoring considered healthy for a software development project?
Continuous refactoring is considered healthy for a software development project because it helps in maintaining clean code, improving the system’s maintainability, reducing technical debt, and enhancing code comprehensibility.
What challenges might one face while practicing continuous refactoring on a legacy system?
Practicing continuous refactoring on a legacy system could lead to challenges like introducing new bugs, breaking functionalities, disruption in the existing workflow, and possible resistance from stakeholders due to the consumption of time and resources without immediate visible benefits.
How can you mitigate risks when refactoring a legacy system?
Risks during refactoring of a legacy system can be mitigated by gradually refactoring in small increments, thoroughly testing refactored code, having a well-defined roll-back plan, and documenting all changes.
Why is it important to ensure that the system’s behavior hasn’t changed after refactoring?
It’s crucial to ensure that the system’s behavior hasn’t changed after refactoring because the goal of refactoring is to improve the code’s readability and reduce complexity without altering the software’s external behavior.
What is a Refactoring Sprint in Scrum and when is it primarily used?
A Refactoring Sprint in Scrum is a sprint dedicated solely to code refactoring, without implementing any new features. It is used when the codebase accumulates a significant amount of technical debt, and the team decides it would be productive to focus on cleaning up the code.
What is a common sign that refactoring is required on a legacy system?
A common sign that refactoring is required include but not limited to: Code smells like duplicate code, long methods, or high complexity code that’s difficult to understand and maintain; Slow development pace due to complexities; High-frequency bugs, etc.
Why might a team need to find the right balance in timing when refactoring a legacy system?
A team needs to find the right balance in timing when refactoring a legacy system because while refactoring can bring long-term benefits, it often does not introduce immediate functionality. If done excessively, it could slow down feature delivery and frustrate stakeholders looking for urgent results.
How does automation testing complement the refactoring process in Scrum?
Automation testing complements the refactoring process in Scrum by providing immediate feedback if a change breaks the functionality and also lightens the load on manual testing. Reliable automated tests increase confidence in making changes, reducing the risks associated with the refactoring process.
When is refactoring considered done in the Scrum development process?
Refactoring is considered done when the code is left in a better state than it was originally, the complexity is reduced and the code changes passed all tests, ensuring the system’s behavior remains unchanged.
Is every change in the code considered refactoring?
Not every change in the code is considered refactoring. Only changes made specifically to improve the code structure without altering its external behavior are considered refactoring.
How does code review contribute to the refactoring process?
Code review contributes to the refactoring process by providing peer feedback on the code changes. It helps to catch potential issues early, validates the refactoring steps, encourages knowledge sharing among team members, and maintains coding standards.
What is “Test-Driven Development (TDD)” and how can it support refactoring efforts?
Test-Driven Development (TDD) is a software development approach where the developer first writes an automated test case that defines a desired improvement or new function, then produces the smallest amount of code to pass that test, and finally refactors the new code to acceptable standards. TDD provides a safety net that aids in the refactoring process by ensuring the system’s behavior remains unchanged.
What is the significance of an Integrated Development Environment (IDE) during the refactoring process?
An Integrated Development Environment (IDE) is significant during the refactoring process as it usually provides features such as refactor commands, syntax checking, autocompletion, which aid in code modification and increase the efficiency of refactoring tasks.
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