An introduction to mutation testing in Ruby

Wed, 18 Jan 2023 19:00 - 21:30 JST

Impact Hub Tokyo

東京都目黒区目黒2-11-3 印刷工場1階


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¥1,500 prepaid
A light meal will be provided


COVID-19 Policy

This will be our first event since COVID-19 started. Having an event is not without risks, but we need your help to keep them minimal. If you are feeling unwell, please do not attend the event. Also, you're required to wear a mask at the event, with the exception of while you're eating.


19:00 〜 19:15 Doors open

Drop by and catch up with your fellow Rubyists. Please note, the doors will close at 19:30, so please arrive before then.

19:15 〜 19:30 Catering served

Thanks to our catering sponsor, we're going to serve a freshly cooked meal. The menu includes a green salad, roasted pork, "vegan fry", Texas caviar, pasta salad, two deli items, and a desert.

19:30 〜 20:00 An introduction to mutation testing in Ruby - Amol Verma

How do you know if your tests are effective? Is code coverage a meaningful way to evaluate your test suite? How often does your test coverage metric prompt you to make meaningful changes to production code?

Code coverage tools like simplecov are commonly used by Rubyists, but can distract from the point of testing: making sure production code is robust and error-free. Mutation testing can be a sensible addition (or even alternative) to your current code coverage strategy.

In this presentation, I'll introduce the practice of mutation testing, demonstrate the process of mutation testing Ruby code, and talk about its pros, cons, and appropriate use cases.


Started using Ruby in 2016. I enjoy pair programming, making high quality products, and process improvement. Team Lead at MediWeb, Inc.

20:00 〜 20:30 Rubyist show and tell

Do you have a cool snippet of Ruby code that you'd like to share, but it doesn't warrant an entire presentation? A challenge with your Ruby application you've been struggling with, and would like some advice? A helpful library or tool you've come across? This is your chance to share it.

For those who'd like to participate, you'll have up to five minutes. There's no need to create a slide deck, but you'll be able to use the projector if you have a code sample or something else to share. While we'll ask you if you'd like to participate when signing up, this is just to gauge interest, and you can change your mind on the day of the event.

20:30 〜 21:30 Open Networking

Discuss the presentations or anything else Ruby related with the other attendees.

Catering Sponsor

TokyoDev helps international developers start and grow their career in Japan. We curate a list of developer jobs in Japan that don't require Japanese, write articles about being a developer here (including our recently published developer salary survey), and have a discord server to discuss developer life here.

Drink and Venue Sponsor

Le Wagon Tokyo is a coding school for startups, creative people and tech entrepreneurs. Our 9-week full-time or 24-week part-time Coding Bootcamps are designed for complete beginners or "half-beginners" who really want to dive into programming and, above all, change their mindset. Learn to think like a developer, consider issues with new insight, and become more autonomous thanks to these newly acquired abilities.

Code of Conduct

Tokyo Rubyist Meetup is a safe and inclusive event. By attending, you agree to our code of conduct.

We're looking for speakers!

Tokyo Rubyist Meetup would love to have you give a talk at a future event. Talks can be anything related to Ruby, and can target anyone from a beginner to an expert. We're happy to help you plan your presentation, so if you have any interest, please get in contact with us, and let us know what you're interested in speaking about.

About this community

Tokyo Rubyist Meetup

Tokyo Rubyist Meetup

Tokyo Rubyist Meetup (trbmeetup) is an event that seeks to help bridge the Japan and international ruby and ruby on rails community. It will hold regular meetings where Japanese Rubyists can commun...

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