How to Test Programming and Coding Skills

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Rafael Timbó
Rafael Timbó
Chief Technology Officer

Table of Contents

There are easy and effective ways to ensure the developer meets the job's technical requirements. This is your guide to learning how to test coding skills before hiring someone.
Published on
August 19, 2022
Updated on
April 16, 2024

Many recruiters hire the wrong person for the job. According to the US Bureau of Labor Statistics, this mistake can result in a loss of at least 30 percent of the hire's expected first-year income for the company.

When hiring IT talent, particularly developers, reviewing a resume won't help in weeding out the best from the rest. Instead, you need to test candidates' programming skills essential for the job.

Fortunately, there are easy and effective ways to ensure the developer meets the job's technical requirements, from analyzing portfolios to creating standardized coding tests. This is your guide to learning how to test coding skills before hiring someone.

Why Are Coding Skill Tests Important?

For any technical position that requires coding or the knowledge of programming languages (for example, testing or quality assurance), it's imperative to test the candidate's coding skills and competencies. Here's why:

Finding the Right Candidate for the Role

A coding trial like an interview programming test can help you find the best person for the job quickly and effortlessly. Hiring is lengthy and costly; no company, especially a startup, can afford to waste resources by hiring the wrong person for the job. For developers, most job duties involve programming, so this is one of the essential skills to test, if not the most important.  

Avoiding Misleading Self-Reported Skills

No matter how great a resume looks, you can't be too sure about self-reported technical skills. It may not even be the case that candidates deliberately add coding skills they don't have. They might think they are good at a programming language, but only a coding test can determine if they are genuinely skillful at it.

Many candidates who lack professional experience make up for it by exaggerating their skills. Therefore, recruiters can't rely on the skills listed on the resumes without testing them in real-life problems or situations.

Maximizing the Hiring Results

Coders often aren't great at marketing their skills. As a result, recruiters may miss out on excellent tech talent simply because their resume doesn't stand out from the rest.

There's already a significant shortage of developers in the US, so startups and enterprises cannot afford to miss out on valuable candidates. The only way to ensure you don't overlook the 'perfect' programmer is to test their programming skills first.

Embedding the Perfect Team Member

Some coding testing techniques can show you more than just the programming talent of your candidates. A live interview programming test can reveal how developers solve a problem step by step. During such a test, you may also get a chance to gauge candidates' soft skills, and experts agree that soft skills are essential for developers. That way, you can determine with higher accuracy how well a person would fit in your team and company.

How to Test Programming Skills

While there are numerous ways to assess a developer's coding skills, not all require actual programming tests. You can use a combination of examinations, interviews, and other methods to ensure someone is a proper fit for your company. Here's what you can do:

Assess Programming Portfolios

Most developers will send in their programming portfolios, even if they don't have extensive experience. As a result, portfolios have become an expected part of the developer job application, even if recruiters do not explicitly ask for them.

Portfolios allow coders to present their technical skills and showcase their best work. The problem with coding portfolios is that they may not always display the programming skills you're looking for as a recruiter. That's why human resources (HR) departments rarely use these documents as a single point of reference.

Still, reviewing a portfolio can give you an insight into the candidate's overall expertise and experience. At the very least, you can determine a developer's general level of coding skills (beginner, intermediate, or expert) in specific programming languages.

More importantly, portfolios can give a recruiter a glimpse of candidates' communication and presentation skills. They can serve as a point of reference for interview questions and further tests, fueling a more efficient and accurate hiring process.

Check Out Candidates' Experience Through Online Accounts

A developer's GitHub account or Stack Overflow presence can give an intriguing insight into their technical expertise. GitHub, for example, offers a way for developers to partake in open source projects and showcase their coding skills to the world. A GitHub repository can substantiate that a developer can collaborate on projects and write code that others can contribute to in the real world.

Here's how you can perform a GitHub account assessment instead of or in addition to an actual coding test:

  • Check how long your preferred candidates have been on the GitHub platform and how many followers they have.
  • Review the number of repositories and the type of projects your top talents have worked on in the past.
  • Compare the number of contributions made to the site by each candidate.
  • Read the codes of your applicants to see how clean and well-structured they are.

GitHub is particularly great for analyzing the coding skills of mobile app developers and game designers. Similarly, Stack Overflow can give you an idea about someone's programming knowledge. Developers' contributions to this tech Q&A platform indicate their involvement in the community and how active they are in learning about new things.

Stack Overflow also has a reputation rate, which other users give on the platform. A high reputation is indicative of regular activity, relevant questions, and helpful answers to questions asked by others. Just by reading these discussions, you can gauge someone's confidence in their coding abilities and knowledge of a particular language.

Perform Programming Tests (Coding Challenges)

Performing a coding test for interviews with job applicants is a common practice in IT recruitment. It's the most direct way to determine coding skills as applicants engage in an actual real-time coding test.

The best way to go about this testing approach is to design a test that resembles the problems or tasks pertinent to the job. This way, you can get an even better evaluation of whether someone is suitable for the particular developer position in your company.

While you can create coding tests from scratch, there are many coding test platforms and briefs you can use to make quizzes. Such platforms allow you to choose a specific language or expertise area (e.g., web development, Python, or DevOps) and formulate questions and tasks around them.

Another benefit of using a coding test platform is that the code is analyzed automatically, giving you actionable performance evaluation in different categories such as correctness, design, readability, and language expertise. This approach comes in handy when you have many candidates to test and run on a limited budget.

Conduct Interview Programming Tests

An interview or live programming test can be even more insightful than a standard coding test because it showcases the soft skills you can miss in portfolios, online accounts, and coding challenges. The procedure is simple. A candidate takes over the task of solving a coding problem in real-time on a shared screen with the interviewer, who observes every step of the process. During the test, an interviewer can ask questions, and the candidate can explain the reasons behind certain decisions.

A live coding test typically requires using a coding test tool. In most instances, it's not a timed test, as recruiters are more interested in observing how the developer solves a problem and not how long it takes. There’s no right or wrong answer for such a test, as the goal is to assess the candidates' coding and working styles.

This form of programming testing is more dynamic than any other testing method and is ideal for DevOps candidates working in a fast-paced environment.

Learn More: Hire Mobile App Engineers: All You Should Know

How to Test Coding and Programming Skills for Different Languages?

Many companies require developers to be skillful in specific programming languages they use for daily operations. As a result, recruiters must test applicants in all those programming languages, which can be time-consuming for both parties.

Fortunately, many languages are interlinked and similar, so testing candidates' knowledge of one primary coding language should suffice in most cases. However, should the job require experience in multiple languages that are significantly different, it's best to conduct unit tests for each language.

Such coding tests require a more intuitive testing environment with language-specific frameworks. They can be challenging to write as each programming language test would require the unit test framework written in the same language. Fortunately, some coding test platforms provide tests you can run in multiple languages, with just specifications for inputs and outputs.

For instance, Qualified is one such coding test platform that allows you to create coding challenges across different languages and frameworks. Its Language Generator tool is ideal for conducting coding skill tests in multiple programming languages.

Coding Skills Test Examples

Creating coding tests and challenges for developers can be easy with the right tools. However, the test should ideally be specific to a programming language and emulate functions the developer will be performing at the job. For that, you need to assess and document the job's technical requirements and create a checklist of duties the developer will take on once hired. This list should guide your coding test challenges.

Additionally, consider whether you want candidates to take tests during, after, or before the interview. It's best to schedule these tests at candidates' convenience, giving them a broader timeframe to fit their schedules. You may also want to inform them about tests' specifics, such as whether they have a time limit.

To give you an idea of coding tests, here are some examples for Python and Java.

Python Interview Programming Tests

Depending on the level of experience and expertise you need for a position, you can conduct simple or advanced Python programming tests.

A Simple Test Brief

You are given a string and required to return the characters in the string. If a character in the string is a digit higher than 6, it should not be included in the array returned.

Input 1: "this is a string"

Input 2: "7 pounds"

Input 3: "125 West 6th Avenue"

An Advanced Test Brief

Here's a comparatively advanced Python test brief:

Find the size of a Tuple in Python by using getsizeof() function.

import sys  

# sample Tuples

Tuple1 = ("A", 1, "B", 2, "C", 3)

Tuple2 = ("Emily", "Alice", "Oliver", "Nikki", "Straus", "Devin")

Tuple3 = ((1, "Ball"), ( 2, "Football"), (3, "Hockey"), (4, "Gloves"))

Interview Questions

Other than technical coding test challenges, here are some interview questions that can help assess the candidate's Python skills:

  • What is Pep 8?
  • What is the difference between lists and tuples?
  • What is PYTHON PATH?
  • What is Flask?
  • What is Django architecture?

Java Coding Tests for Online Interviews

Java is one of the most in-demand programming languages, and testing a candidate in it is a great way to ensure you're getting the right person to do the job. While it's an easy programming language, Java is also incredibly versatile.

Depending on the level of expertise the job requires, the Java coding test can include basic programming functions or advanced problem-solving.

Here are some basic Java programming test tasks you can give candidates:

  • Reverse a string
  • Swap two numbers without using a third variable
  • Check if a given number is a prime number
  • Check for palindrome string
  • Sort an array in ascending and descending order
  • Reverse a linked list
  • Look for the same elements in two arrays
  • Shuffle an array
  • Program to show inheritance
  • Merge two lists
  • Overriding example

Further Resource: Hiring Vetted Developers

Use Coding Tests to Find the Best Tech Talent

Now that you know how to test coding skills, you can design custom programming trials and hire the most suitable developers for your company. But where do you find the right tech talent to help your business grow in the long run?

Revelo can connect you with the creme de la creme of developers from Latin America. We gather professionals pre-vetted for their tech skills, experience, and English proficiency. All that's left for you to do is conduct your coding tests and hire the perfect pick.

Contact us today to learn more and start scaling your team.

Need to source and hire remote software developers?

Get matched with vetted candidates within 3 days.

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