Hiring guide for Elixir Testing Engineers

Elixir Testing Developer Hiring Guide

Elixir is a relatively new functional programming language that has been gaining popularity in recent years. It was created in 2012 by José Valim, who was previously the lead developer of Ruby on Rails. Elixir is designed to be used for building scalable, maintainable, and concurrent software applications. It is built on top of the Erlang VM, which provides a number of features that make it well-suited for this purpose, such as fault tolerance and hot code reloading. Elixir has a number of features that make it a good choice for testing software, including a built-in test framework and a strong community of developers who are actively creating and sharing testing tools and techniques.

Ask the right questions secure the right Elixir Testing talent among an increasingly shrinking pool of talent.

First 20 minutes

General Elixir Testing app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Elixir Testing application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

What is the purpose of testing in Elixir?
The purpose of testing in Elixir is to ensure that the code behaves as expected, to prevent bugs, and to make the code more maintainable and easier to refactor.
How would you write a basic test in Elixir?
In Elixir, you would use the ExUnit framework to write a basic test. You would define a module, use ExUnit.Case, and then define test functions with the 'test' macro.
What are the main components of ExUnit?
The main components of ExUnit are the test cases, which are modules that use ExUnit.Case, and the tests, which are functions that use the 'test' macro.
How would you run tests in Elixir?
You would run tests in Elixir using the 'mix test' command in the command line.
What is the role of 'assert' in Elixir testing?
'Assert' is used in Elixir testing to check that a certain condition is true. If the condition is false, the test fails.
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What you’re looking for early on

Does the candidate have a deep understanding of Elixir and its testing frameworks?
Can the candidate demonstrate problem-solving skills?
Is the candidate familiar with Test-Driven Development (TDD)?
How well does the candidate understand software development methodologies?

Next 20 minutes

Specific Elixir Testing development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you test asynchronous code in Elixir?
You would test asynchronous code in Elixir using the 'async: true' option in your test case module. This runs the tests in the module concurrently.
What are fixtures in Elixir testing and how would you use them?
Fixtures in Elixir testing are a way of setting up the environment for tests. You would use them by defining a setup function in your test case module.
Describe the difference between 'assert' and 'refute' in Elixir testing.
'Assert' checks that a condition is true, while 'refute' checks that a condition is false. If the condition for 'assert' is false or the condition for 'refute' is true, the test fails.
How would you test private functions in Elixir?
In general, you should not test private functions directly in Elixir. Instead, you should test the public functions that call them. If a private function is complex enough to need direct testing, it should probably be a public function in another module.
What is mocking in Elixir testing and how would you use it?
Mocking in Elixir testing is a way of simulating the behavior of real objects. You would use it by creating a mock object and defining what it should return when its methods are called.
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The ideal back-end app developer

What you’re looking to see on the Elixir Testing engineer at this point.

At this point, a skilled Elixir Testing engineer should demonstrate strong problem-solving abilities, proficiency in Elixir Testing programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Elixir Testing.

What does this simple Elixir code do?
IO.puts 'Hello, World!'
This code prints 'Hello, World!' to the console.
What does this Elixir code do?
defmodule Math do
  def add(a, b) do
    a + b
This code defines a module called 'Math' with a function 'add' that takes two parameters and returns their sum.
What will be the output of this Elixir code?
list = [1, 2, 3, 4, 5]
Enum.map(list, fn x -> x * 2 end)
This code multiplies each element in the list by 2 and returns a new list with the results. The output will be [2, 4, 6, 8, 10].
What does this Elixir code do?
spawn(fn -> 1 + 2 end)
This code creates a new process that executes the function given as an argument. The function simply adds 1 and 2, but the result is not captured or used.

Wrap-up questions

Final candidate for Elixir Testing Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Elixir Testing application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you handle errors in Elixir tests?
You would handle errors in Elixir tests using the 'assert_raise' function, which checks that a certain exception is raised.
What are the benefits of property-based testing in Elixir?
The benefits of property-based testing in Elixir include the ability to test a wide range of input data, the ability to find edge cases, and the ability to shrink failing test cases to their simplest form.
How would you implement property-based testing in Elixir?
You would implement property-based testing in Elixir using the StreamData library. You would define properties that your code should have, and StreamData would generate test data to check these properties.

Elixir Testing application related

Product Perfect's Elixir Testing development capabilities

Beyond hiring for your Elixir Testing engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Elixir Testing projects, and can engage in multiple capacities.