CodeSubmit Interview Series

The 12 Best Ruby Developer Interview Questions in 2023

Are you hiring your next Ruby developer? Then, you need the top Ruby developer interview questions. We’ve listed the 12 best questions here below. Read on!

Interviewing Ruby developers  

Ruby is an interpreted, high-level, and general-purpose programming language, which was designed for productivity and simplicity. It’s especially useful for building desktop applications, static websites, data processing services, automation tools, servers, DevOps, and web scraping and crawling. 

Ruby is, in other words, a versatile language with many use cases. But what are the top Ruby developer interview questions? Here you go: 

Beginner Ruby developer interview questions

In this section, we’ll look at the best junior developer interview questions. Ruby is an excellent language for junior developers because it’s simple and easy to learn. These questions focus on less technical to better fit developers who lack experience.

1. What is Ruby? 


Ruby is an interpreted, high-level, and general-purpose programming language. It was designed for productivity and simplicity and supports multiple programming paradigms. Everything is an object, including primitive data types. 

2. What are the benefits of using Ruby? 


Everything in Ruby is an object, including classes, booleans, and methods. This makes the language much simpler than other languages and opens up possibilities. 

It’s also an open-source language with a large community and it’s one of the best languages for metaprogramming (writing code that can act on other code instead of data). Ruby also has clean and simple syntax, which allows developers to solve complex problems with fewer lines of code and write more readable code. 

3. What are the four variable types in Ruby? 


The four variable types are: 

Global variables: These variables begin with $. They’re accessible from anywhere within Ruby, no matter where they are declared and should be handled with care.

Local variables: Lowercase variables begin with a lowercase letter or an underscore. They are confined to the code construct within which they are declared. 

Class variables: These variables begin with @@ and they’re shared by all instances of the class that they are defined in. 

Instance variables: These variables begin with @ and are similar to class variables, except they are local to a single instance of a class where they are used. 

4. What different class libraries are used in Ruby?


The different class libraries in Ruby are:

  • Network programming

  • CGI programming

  • Text processing

  • GUI programming

  • XML programming 

Advanced Ruby developer interview questions

Next, let’s take a look at advanced Ruby developer interview questions. These are questions to ask senior Ruby developers and they’re more focused on the technical aspects.

5. What is the role of thread pooling in the thread lifecycle in Ruby? 


The lifecycle of a single thread starts automatically when CPU resources are available. The code is run in the block where it was instantiated and obtains the value of the last expression in that block and returns it when completed. Threads use resources but multiple threads running at the same time can improve app performance. 

Thread pooling is a technique where many pre-instantiated reusable threads are left on standby so that they can perform when needed. Thread pooling is optimal for multiple short tasks that must be performed. The overhead avoids having to create a new thread for every small task. 

6. What is the role of modules and mixins in Ruby?  


Modules are used to group methods, classes, and constants to provide a namespace for preventing name clashes in Ruby. Modules are also used as mixins, which make it possible to share code among different classes without giving up the simplicity of the single inheritance paradigm. 

7. What’s the role of the Rails Controller? 


The Rails Controller is the logical center of the application and it facilitates interaction between users, views, and the model. The Rails Controller is also: 

  • Capable of routing external requests to internal actions

  • Regulate sessions so that users feel they are interacting on an ongoing basis with the application 

  • Regulate helper modules so that capabilities can be extended of the view templates without bulking code 

8. What are blocks and procs? 


A block in Ruby is a version of a closure; a block of code that can be wrapped up into a proc, which is a type of function. The block can then be stored in a variable or passed to a method and run when wanted. Blocks can be syntactically written as blocks of code between the do and end keywords or { }. 

9. What are the three ways in which you can compare Ruby strings?


These are the three ways in which you can compare Ruby strings:

  • With == : Returns true or false

  • With casecmp: Returns 0 if matched or 1 if not matched 

  • With eql? : Returns true or false 

10. What are the levels of access control for Ruby methods? 


There are three levels of access control for Ruby methods:

Public: These can be controlled by anyone

Protected: These can only be accessed with their defining class and subclasses

Private: These can only be accessed and viewed within their defining class 

11. Explain Ruby arrays. 


Ruby arrays, which are ordered collections of objects, can hold objects like number, hash, integer, string, or symbol. Ruby array indexing starts with 0 and the negative index starts with -1. Ruby arrays can be created with a literal constructor [] or using a new class method. 

12. In what ways can items be added to an array in Ruby? In what ways can they be removed?  


Ruby array elements can be added in these ways:

  • unshift

  • insert 

  • push or <<

They can be removed in these ways:

  • pop 

  • delete 

  • shift 

  • uniq

Over to you!

There you have it! Now you have Ruby developer interview questions to use at your next interview. 

But interviews are just one part of technical hiring processes. You also need to assess your candidates’ technical skills.

That’s what CodeSubmit can help you with. Our technical assessment platform supports pair programming, take-home challenges, and screening bytes.

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