Anubhuti ShrivastavaAnubhuti ShrivastavaFebruary 19, 2019


Ruby on Rails (RoR) is a flexible and collaborative web development framework which works on the principles of an agile and iterative approach to building web apps and solutions.

It has become an integral tool for businesses to create customised web apps quickly without compromising on the quality.

But to hire Ruby on Rails developers is a challenging task for entrepreneurs as it’s a fiercely competitive marketplace where there’s limited availability of experienced Ruby developers in the niche Ruby development domain. In such a scenario, it becomes much more significant to hire and retain superior RoR professionals.

This issue can be addressed with exploring this definitive guide to interviewing the RoR wizards in the right manner. Here, we have come up with common interview questions for RoR developers that will allow you to get an idea of how well they can expound their awareness and intellect of the domain. Let’s take a look at four such questions…

1. Questions related to Ruby in order to test the applicant’s expertise in basic language concepts & skills to write code for business apps

First phase

You might wonder what the point is of asking Ruby related questions to a RoR programmer? But as the framework is written in Ruby, the developer should be aware of all the ins and outs of the language.

While you may go through the engineering resume, assessing their Ruby knowledge will allow you to spot the programmers who have the capacity to write quality code by using their understanding of the basics of Ruby language. You can ask questions related to the key concepts of Ruby, such as inheritance, class hierarchies, polymorphism, object-oriented design patterns, etc.

In case the potential programmer answers the first round of questions well, you can easily consider him for being eligible to appear in the next round and take the interview process further.

Second phase

After examining the fundamental language expertise it’s mandatory to assess the applicant’s capability to write code for business apps. Here, you have to judge their ability to work efficiently with key Ruby interfaces such as Rack which makes it possible to create a Ruby app.

In order to assess this skill, you should ask the interviewee questions related to Rack such as its definition, how does it work, rack application interface, etc. Also, you can make him write a simple Rack application.

Third phase

In the third phase, you will be examining the applicant’s ability to recognise the basic configuration of a Ruby library. Being a popular programming language, Ruby is blessed with an enthusiastic community of programmers who strive to develop and maintain several useful libraries.

This is the reason why RoR developers must have the knack of taking advantage of this third-party code in order to accelerate and simplify the entire development process. It will give you an idea of their ability to understand code written by experts. In addition, you can ask questions related to Ruby gems which is an integrated system built to let programmers easily construct, share, and apply gems.

2. Questions related to Ruby on Rails in order to test applicant’s proficiency in the framework

The second set of questions will be dedicated to the RoR framework in order to assess an applicant’s familiarity and skill to work efficiently with the platform for building scalable apps and solutions. You can ask the following questions:

a. General questions related to Rails framework, such as:

I. What is your definition of a Rails engine?

II. What do you understand by Asset Pipeline?

b. Questions associated with main parts of a business app routing, controllers, and views, such as:

I. How do you describe CRUD verbs and actions?

II. What is that we need to test in controllers?

c. Queries related to ActiveRecord in order to understand an applicant’s ability to comprehend the Model part of an app, such as:

I. How will you define Object-Relational Mapping?

II. What are the major types of associations in Active Record?

d. Questions related to security of RoR apps by understanding an applicant’s knowledge of possible attacks and their solutions, such as:

I. What do you mean by a session mechanism and how does it work?

II. Explain the difference between CSS Injection and SQL injection.

e. Questions associated with automated testing of RoR apps in order to judge applicant’s capability to enhance the workflow. The RoR professionals must have a comprehensive understanding of automated testing, its types, and the reason to write them.

I. State your two favourite tools for writing unit tests.

II. What primary technique do you use for writing tests?

f. Questions related to refactoring to get an idea of an RoR programmer’s ability to polish the existing code they’ve written to make it more efficient and cleaner. This skill will allow developers to produce code that can be easily maintained and expanded. Here, it’s a good idea to ask questions such as:

I. Why should you avoid fat models and controllers?

II. What do you mean by a code smell and what are your favourite tools to spot them?

3. Allocate a pair programming task and give them a home assignment

Assigning a pair programming task allows you to check an applicant’s ability to work in harmony with senior professionals in the team. Also, it’s the best way to understand their mindset and get a grip on their line of thought.

Therefore, after screening the candidate on all the above questions, make them share the screen with a senior programmer and solve a task. After comprehending the problem, the applicant can suggest a few methods to solve in accordance with their expertise. And, the senior professional can let him understand the big picture and what can be the best solution to it.

In the end, you should provide the RoR developer with a home assignment in order to check their ability to use multiple frontend and backend technologies for seamless web development. Also, by evaluating the outcome you can get an idea of their proficiency in JavaScript, its libraries, markup language, and stylesheets.

If you find the result above satisfactory, you can make the final call to hire that RoR professional because a home assignment can be the ultimate yardstick to judge their expertise and intellect.

There can be several other questions that you can ask when interviewing a RoR programmer when they apply for a job. But the above-mentioned are the most important ones to ensure that you hire the best RoR developer who will definitely be a great asset for your organisation.

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