What is a code review and how to perform one?

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Emil Waszkowski
What is a code review and how to perform one?

Regular code reviews prove to be an important part of the software development process. While automated tests, peer reviews and quality assurance can catch mistakes, mistypes, architectural flaws and some other limitations - in many cases, only a fresh pair of eyes can assess whether the design, logic, and quality of the code are up to standard. 

If your existing app is not performing as fast and seamlessly as it should, or you’ve been struggling to add any new features for some time now - it’s high time to think about outsourcing code review and consider implementing regular reviews in the future to avoid such issues (if you haven’t already). 

Here’s why code reviews matter and how to do them properly, either in-house or with some help from an experienced software development company like us. First things first, however:

What is code review?

Like any other human creation, software is prone to mistakes. With code reviews, however, these mistakes can be kept to a minimum. 

Essentially, code review is the process of assessing code and its quality to find areas for improvement or code smells, as well as to identify bugs, errors, and part of the code that might not be up to quality standards set by the organisation. 

Usually, it’s the fellow programmers who check each other’s code for mistakes, but the code review process can also be performed by a specialised software development company, especially if you plan to hire one. 

Why code review?

It might not seem like it at first, but regular code reviews are capable of streamlining and accelerating software development like no other. A while back, the Best Kept Secrets of Peer Code Review already revealed the following benefits: 

  • Improved code quality 

  • Fewer mistakes in the code

  • Shorter development and test cycles 

  • Increased user satisfaction

  • Reduced impact on technical support

Since then, however, there are a few other code review benefits that can be added to the list. In fact, having a fellow developer reviewing code is said to be the most effective way to find and eliminate problems while coding nowadays. 

When done right, code reviews streamline development, save time, the amount of work needed from Quality Assurance teams, and often money in the long run. What’s also worth taking into account is that regular code reviews contribute to the sense of "ownership" for any piece of code that developers write, and serve as a great opportunity to learn for more junior members of the team

Given these benefits, it shouldn’t come as a surprise that code reviews are seen as a valuable part of the software development process by many product owners. The truth is that any team can benefit from code reviews, regardless of technology and development methodology in place. Let’s take a closer look at how to review code, then. 

How does code review work?

As with any other important piece of the puzzle, code reviews should integrate with the existing software development process. If you plan to initiate code reviews in your organisation, you should start by deciding who would be involved in it in the first place. 

There are different ways in which code reviews can be performed: 

  • Notifying all software developers in the team. Once a given piece of code is ready for review, it’s sent around to all available software developers. Whoever will have some time for it first, they are going to review the code. This approach certainly allows for more flexibility, but since there’s no specific person responsible for the code review, it might not be done in the end. 

  • Leveraging pair programming. This approach makes two developers working on the same code together and checking each other’s work. But, since both of them are kept close to the code, they might be subjective at times. Not to mention that pair programming also requires more resources (time & team members) than some other methods. 

  • Having specific senior developers/team leaders involved in the code review process. This “over-the-shoulder” method is one of the easiest ways to perform a code review. Once the piece of code is ready, developers should have a specific colleague assigned (the more senior, the better) to review their work. This can either be done remotely or in-person. 

When doing code reviews “in-house”, it’s also important to decide on timelines, iterations, and requirements for submitting code for review. Once you get that covered, you should familiarise your development team with the code review process and make sure it gets implemented properly.  

What to look for when performing a code review, then? 

When doing a code review, there are different factors that should be taken into account: 

  • Requirements: Are all cases fully implemented?

  • Purpose: Is there a reason for every change made by the developer?

  • Logic: Are there any obvious logic errors in the code?

  • Design: Is the code well-designed? 

  • Functionality:  Is the way the code behaves good for its users?

  • Complexity: Could the code be made simpler? 

  • Tests: Are the automated tests sufficient for the code? 

  • Style: Does the new code conform to existing style guidelines?

  • Documentation: Was the relevant documentation updated?

  • Naming: Are the names for variables/classes/methods clear enough? 

  • Comments: Are the comments concise and useful? 

The exact criteria might change, but the aim stays the same: no matter the code review process you have in place, it’s crucial to review every new line of code, aim to improve its quality and help developers to get better at coding in the long run. In case you need some more guidance, here’s a set of best practices in code reviews. 

Code review - best practices 

  1. Establish what to look for in code reviews. As already mentioned, there are at least a few important criteria to keep in mind when performing code reviews. Set your standards and make sure your code reviewers follow them every time.

  2. Test thoroughly before reviewing the code “manually”. Time is of the essence - don’t waste it on tasks that can be automated. Ideally, you’d perform the review after code passes the automated checks, and then deploy it. This approach will allow you to cut down on errors and save time in the code review process.

  3. Keep it short (relatively). Research shows that after spending 60 minutes on code reviews, performance and attention to detail are not as sharp. The best practice seems to be reviewing between 100 and 300 lines of code at once, and spending 30-60 minutes on it every single time. 

  4. Give constructive feedback. This should go without saying, but being constructive rather than critical in your feedback is essential to keep the team morale high and continue to learn from mistakes made. Code reviews play an important role in software development, which is why it’s crucial to foster a positive experience around them. 

  5. Have a process for drawing conclusions and fixing the code. Identifying bugs is one thing, but fixing them is a different story. It might seem obvious but many development teams don’t have the process in place for fixing the issues they discovered. Make sure it’s not the case with your team.  

Code review as a service

With existing software, you also might want to check the quality of the code and efficiency of the chosen technology up till now. In such cases, getting a fresh pair of eyes and outsourcing code review is a common practice. 

Code reviews performed by external specialists make it possible to assess the used technology and written code in terms of efficiency, scalability, usability, costs and further development. It comes in useful especially when you plan to grow your product or outsource its development to a different team. 

There are a few other benefits that stem from outsourcing code review, though:

  • Outsourcing code reviews to developers who actually specialise in them can bring your business much better results. Programming skills don’t always translate into reviewing skills, which is something to keep in mind.

  • Outsourced code review presents an unbiased, third-party perspective. Rather than taking into account who exactly wrote the code, an external team of specialists focuses solely on the code and its quality. 

  • Outsourcing code review can help you avoid technical debt. Being proactive about code quality can save you a lot of money and time in the long run. Actually, research shows that technical debt and maintenance issues can consume even 42% of a developer’s time, which should be a good enough reason to outsource code reviews every now and then.

How do we perform code audits at Future Mind 

At Future Mind, we have an experienced team of developers who create complex solutions for a range of industries, including retail and insurance applications that have to be compliant with the highest standards, scalable, and able to serve millions of users. Code reviews are an important part of the whole process - and we perform them for clients with existing products as well.   

As a matter of fact, when reviewing an existing product and its code, we check the quality of the software, the architecture, and app efficiency to evaluate usability, scalability, and the potential for changes and further development. The results of our review are presented in a comprehensive audit report, along with improvement recommendations.

In a nutshell, Future Mind’s audit report includes the evaluation of: 

  • App architecture 

  • The correct use of chosen technology and libraries

  • Review of the core source code fragments based on style, standards and best practices

  • Code performance & efficiency

  • The scalability of the source code

  • The quality and reliability of the software development process 

  • The quality of the automated tests: their scope & coverage

  • The clarity & readability of the code, and the easiness with which new team members can be onboarded 

  • Findings & recommendations

The whole code review process takes approximately 2 weeks and is performed by a senior developer. 

Since code review is a fast method for checking the efficiency and quality of the existing source code, as well as evaluating its potential for growth - you might want to consider it when your app users report bugs and low performance, or you simply want to find out whether the app is being developed with the highest standards and best practices in mind. 

In both cases, you can turn to software development specialists for a comprehensive code review. As usual, we’re here to help.

Authors

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Emil Waszkowski

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