Complete hiring guide for Ruby developers

By the end of this hiring guide article, you should have a clearer understanding of all the essentials needed to find and hire the best Ruby developer for your business needs. Since Ruby is constantly in-demand over time, it’s beneficial to know all there is to know before you start the overall hiring process.

Finding the perfect Ruby developer for your needs can be exhausting. You should anticipate that you will likely need external assistance or a specialist for interviewing and hiring to help you with their expertise and knowledge. No matter how much you know about development and interviews, some things are better delegated to those specialists for the best possible outcome.

Because it’s not an easy job to find and hire the best developer, you will need to go over several factors that cover everything from skills, expertise, professionalism, and related questions—in the sections below. Moving forward with the right professionals is simple after seeing the whole process's essentials.

About Ruby

Ruby is an object-oriented and dynamically typed programming language for the general purpose of building web servers and web apps. It has an elegant and simple syntax that’s easy to read and write.

This programming language is focused on productivity and simplicity through its superbly readable code and comprehensive and practical libraries. With Ruby, development becomes optimized and scalable. Due to these features, Ruby is widely used in-app and web development, CMS (content management system), eCommerce, and other fields.

Released back in 1993, Ruby is a blend of programming languages (Ada, Perl, and Eiffel) and the most long-lasting.

Stats about Ruby

If you look at the stats for Ruby, you can conclude the facts about popularity, usability, preferences of devs, and more.

In a Stack Overflow survey for 2021, only 7.89% of devs that responded said they want to work with Ruby, which does not add too major points for popularity, but at the same time, such a percentage adds to the demand and scarcity of devs that work with Ruby.

Similarly, for Ruby’s framework, Ruby on Rails, the same percentage of devs voted for its usage or 7.89%.

Regarding the salary of a Ruby dev, the approximate yearly salary is $129,101, or from $94K up to $193K. We can conclude that Ruby developers belong to the high-salary range developers.

Interviewing a Ruby developer

Helpful tips for a pre-screening interview

For the interviewing and hiring process to go smoothly, it is essential to leave some things to professional talent acquisition specialists. Such a specialist focuses on a few things to evaluate the candidates or if they will go further with the process with those candidates.

Every time they inquire about the dev candidates, they pay attention to the language compatibility or whether or not the candidate is fluent in English. Along with this, they observe if the candidate has the needed skills, relevant experience, good soft skills, and other relevant factors that could appear along.

Before hiring occurs, the talent acquisition specialist gathers all of this information and collects the impressions before moving forward. The whole process must encompass checking theoretical knowledge, assigning code tests, and checking soft skill aspects hand in hand.

Technical skills of a Ruby developer

A skilled Ruby developer needs to tick off the following relevant technical skills:

• Knowledge of the Ruby syntax and object-oriented programming
• Ability to write Ruby libraries that are reusable
• Knowledge of Mocking, RESTful, and MVC (model-view-controller)
• Experience in embedded and external databases
• Ability to use various helping tools (Rake, Bundler) and tools for code versioning (SVN, Git, Mercurial)

We asked Ruby on Rails developer Albin Hasaj, and he added the following technical skills to look for in a Ruby developer:

“An experienced Ruby developer has to know their way around automated testing with Unit or Rspec, but they also need good experience with API (GraphQL or RESTful). Another good technical skill to have is extensive knowledge of Active Record (or a system layer used to represent business logic and data). It is also expected to know the cons of some Ruby methods, their differences, and their speed”.

Albin Hasaj

Non-technical skills of a Ruby developer

The non-technical skills are just as essential as the technical ones because no matter how skilled someone is, the work dynamic will likely suffer if they are challenging to work with or lack other professional skills.

The experts that check such skills, talent acquisition specialists and recruiters, pay attention to a few things during the interviewing.

They check for English proficiency, guaranteeing no language barriers and obstacles to further communication with clients.

Another thing they check is how professional someone is, based on their punctuality, dress code (appropriateness in overall appearance, showing up on the call on time, etc.), and the general attitude of the interview.

Ruby interview questions and answers

When it’s the time to ask questions for a more in-depth expertise check and more concrete Ruby experience questions, you can assemble a list of the following questions, as well as other relevant ones you add as well:

1. Is Ruby flexible?

Expected answer: Ruby is a scripting language that is incredibly flexible, and it is known for this exact thing as well. When we use Ruby, we have the freedom to change the programming elements as we need them to be at a given instance. We can rephrase something or even remove it altogether.

2. What is the meaning of ‘length’ in Ruby?

Expected answer: Length is the term used for a String class method, and we use this built-in method in Ruby when we need to define the length of some character within a string precisely.

In summary, this function/method is the easiest way to define a string length in Ruby.

3. List the data types in Ruby.

Expected answer: there are six types of data in Ruby:

• Strings—The strings in Ruby are multiple character sequences. They could consist of symbols, numbers, or letters.
• Hashes—The hash represents a key-values collection, and they are always paired.
• Booleans—Boolean represents a value that can be true or false. In Ruby, when we have an instance in ‘true’, it belongs in the class TrueClass (and ‘false’ in the FalseClass).
• Numbers—Here, we have imaginary numbers, decimals, fractional numbers, etc.
• Symbols—When we have an object value that’s a number, not a vector, we use it as an identifier. Symbols, in this case, are similar to strings and very useful for data work.
• Arrays—When we have collections of literally any object, we call them ‘arrays’, but only if the integers are indexed, and there is a precise order.

4. What are Ruby class libraries?

Expected answer: The grouping of domains like data types, thread programming, and other domains of various types are called class libraries. With these libraries, we get many benefits regarding flexibility of the libraries handling, especially for the creation of scripts in Ruby.

The most useful class libraries of Ruby are:

• GUI programming
• CGI programming
• XML programming
• Text processing
• Network programming

5. What is args in Ruby?

Expected answer: args is short for arguments. Now, in the Ruby context, when we see args, it means that in our code, a certain amount of arguments are accepted by the method, and they are in an array.

In general, though, Ruby arguments are obligatory elements that we need for method invoking. Without an ‘argument’, we would not be able to call (invoke) the method we need.

6. Elaborate on Ruby ‘closures’.

Expected answer: The closures in Ruby represent a block of code or a function that could take on a role of a variable and also as an argument when passed to a function. When we need to execute a lot of code, we gather it under the name Closures.

The closures in Ruby are divided into three types:

• Blocks—This closure type is quite simple and represents a code part, not an object. This code part is found between do…end (indicating the code in a specific script section) or between {}. Blocks require no naming and are anonymous.
• Procs—Procs represent encapsulations of a code block. Procs and blocks have some similarities but are quite different nonetheless. We can pass more than one proc to a method and store procs to local variables.
• Lambdas—The Lambdas are very similar to procs, but the difference is that lambdas need the exact argument number that is passed to them. With Lambdas, we can encapsulate data and logic in variables that are portable.

7. Elaborate on Ruby variables.

Expected answer: The locations that keep the data stored and intended to use for programs are called Ruby variables, all named differently.

Ruby stands out from other languages because, in this case, we don’t need variable declaring.

There are four variable types in Ruby:

• Instance—This variable always starts with ‘@’, and we can access this from many method instances, and it belongs in just a single class instance.
• Global—This variable starts with ‘$’, and we have access to it, regardless of where we are in the program.
• Local—This variable always starts with an underscore symbol, or a lowercase letter, and we can have access to it when we initialize it in its block.
• Class—This one starts with ‘@@’, and before we use them, we have to initialize them. The access to this variable is not dependent on where we are in the class.

8. Explain the process of ‘freezing objects’ in Ruby.

Expected answer: If we need to ensure that there will be no modifications to an object, we use the method freeze in Ruby, and with it, we easily create objects that are immutable. If we try to modify an object (that previously invoked the method freeze) in this case, the outcome will be a runtime error by the program.

To test if this action was successful, we just need to use Object#freeze. Ideally, the result will be true (meaning ‘frozen’). Otherwise, it will be false.

9. How do you explain ‘loading’ and ‘requiring’ in Ruby?

Expected answer: Load and require are methods in Ruby that are used in work with code.

More precisely, when we use ‘load’, we enable the reading and parsing of files on every occasion when we execute that file. It’s best to use this method when we want to load other files’ code to get code updates timely (if the files change often and dynamically).

‘Require’ is the method we use when we need to load a file and have all its statements executed. This method imports every definition of a method and the classes in that exact file.

10. How do we invoke a method in Ruby?

Expected answer: If we need to call (invoke) a method, we need to type the name of the method and the passing as well—we do this in the arguments.

There are quite a few (out of many) ways to invoke a method, for example, by:

• Skipping brackets
• Using ‘tap’
• Using ‘to_proc’ for the function name
• Using ‘method_missing’
• Using ‘eval’
• Using ‘send’, as well as ‘public_send’
• …and others.

Hasaj added asking the following questions to ensure the newly hired Ruby developer meets the job requirements with their expertise:

• How would you handle N+1 queries?
• What is your experience with Rescue?
• Do you measure the speed of a newly written code? How?
• What is your experience with automated testing?

Essentials and assessment of a Ruby developer

During the process of finding, interviewing, and hiring a Ruby developer, these are the main points you should consider in the developer:

• Good knowledge of the Ruby syntax—writing basic and advanced elements (modules, loops, classes, etc.)
• OOP programming
• Knowledge of ERB/Haml—common templating systems
• MVC paradigm—RoR framework structure with its layers for structuring
• Unit testing through Rspec
• JSON and API experience
• HTTP and REST protocols

Further, Hasaj explained more about the essentials of a Ruby developer:

“The Ruby developer needs to know how to evaluate situations where they implement solutions. They should know when to use SQL query or Active Record or when to remove the N+1 query. And of course, the assessment can be well-rounded by checking the live coding logic too.”

What distinguishes a great Ruby developer from a good one?

Selecting the perfect Ruby developer candidate can become tricky when you receive many applications with good and exquisitely great developers. So, how would you differentiate between the good and ideal ones?

The genuinely great Ruby developer will not only have the crucial technical skills and expertise, but they will also have a visionary mindset with critical thinking for solutions. They would fit well individually or within a team, regardless. The ideal Ruby developer also takes pride in intuitively understanding the work.

Also, the Ruby developer that stands out from the other potential candidates knows a lot about automated testing and Active Record.

Possible challenges during the hiring of a Ruby developer

As with every process or hiring-related issue, some challenges could pop up.

For example, hiring unsuitable developers because you didn’t leave the screening to professionals who also review the received applications. Hiring an unqualified Ruby developer is not a good investment for any business. Do not fall into the trap of hiring a less costly developer and thinking you save money—if you need a top-tier or highly expert developer, hire that one.

Another challenge is testing for the wrong skills or asking questions that vaguely answer questions about the experience with Ruby. Do not rely just on what you see on the resume; try to ask more in-depth questions too.

Why and when do you need to hire a Ruby developer?

An experienced Ruby dev is always expected to ensure outstanding quality, performance, and responsiveness of the applications. They also need to design, build, and in the long run, maintain the Ruby code, which needs to be reliable.

Not only this, but Ruby dev is an excellent asset when you need someone to ensure the automatization and quality of the code, detect bugs and propose solutions for development issues.

In a nutshell, you need to hire a Ruby developer if you need improvement in:

• Scalability
• Development speed
• Versatility (of apps with a rich spectrum of features)
• Cybersecurity
• eCommerce fields
• The content aspect of the business
• Faster processing
• Consistency in development

In general, companies hire Ruby developers because they need simple development, optimization at a high level, as well as cost-effectiveness.

Benefits of Ruby

Ruby is a highly reliable programming language and comes with Ruby on Rails as its framework. All developers working with it can build many high-quality web apps with clean and crisp architecture and include all JavaScript, CSS, and HTML files.

Because this programming language is simple, it simplifies all code changes. For developers, demanding projects with a large volume of changes are easily managed in this case.

Ruby is also highly secure and trusted. With Ruby, developers can store and even hold all the objects needed, and thus they prevent hijacking or overwriting of finished files or sensitive information.

Much faster processing is another benefit of working with Ruby. The developer can efficiently operate multiple programs simultaneously, and systems won’t slow down—a perfect solution for projects of urgent ETA.

Ruby is also flexible, open-source, and consistent. This means developers can quickly come to some solutions with the Ruby open-source rich library. Also, the syntax is consistent and simple and can provide answers without needing the time-consuming learning process from scratch.

Regarding the benefits of working with Ruby, this is what Hasaj further said:

“Ruby is amazing when writing database queries with a Ruby code and Active Record. All of the methods of Ruby are simple to work with and define, and the app structure itself is practical, as well as the code architecture. The developer needs less time for code writing than other programming languages”.