Rubocop VS Scientist

Compare Rubocop vs Scientist and see what are their differences.


A Ruby static code analyzer and formatter, based on the community Ruby style guide. [Moved to:] (by rubocop-hq)


:microscope: A Ruby library for carefully refactoring critical paths. (by github)
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Rubocop Scientist
7 18
11,323 7,340
- 0.3%
9.8 1.9
about 3 years ago about 5 hours ago
Ruby Ruby
MIT License MIT License
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.


Posts with mentions or reviews of Rubocop. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2022-06-28.


Posts with mentions or reviews of Scientist. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-12-05.
  • Crates that run multiple versions of a function and ensures the return value is the same?
    2 projects | /r/rust | 5 Dec 2023
    For some google-fu, the ruby / .NET equivalent of this is /
  • Scientist: A Ruby library for carefully refactoring critical paths
    1 project | /r/hackernews | 18 Nov 2023
    6 projects | | 14 Nov 2023
    The readme (here doesn't mention, but here is one for Rust:
    1 project | | 18 Oct 2022
  • Test Against Reality
    1 project | | 9 Jul 2023
    Something I've learned in Ruby land (prob standard in other places, forgive my ignorance) that seems a bit different than what the article advocates for (fake services):

    - Write your service wrapper (eg your logic to interact with Twilio)

    - Call the service and record API outputs, save those as fixtures that will be returned as responses in your tests without hitting the real thing (eg VCR, WebMock)

    - You can now run your tests against old responses (this runs your logic except for getting a real response from the 3rd party; this approach leaves you exposed to API changes or you have edge cases not handled)

    For the last part, two approaches to overcome this:

    - Wrap any new logic in try/catch and report to Sentry: you avoid breaking prod and get info on new edge cases you didn't cover (this may not be feasible if the path where you're inserting new logic into does not work at all without the new feature; address this with thoughtful design/rollout of new features)

    - Run new logic side by side to see what happens to the new logic when running in production (

    I use the first approach bc small startup.

  • Real-World Engineering Challenges: Migrations
    2 projects | | 18 Oct 2022
    Check out GitHub scientist if you are doing a migration with a ruby based system:

    Great support and functionality for testing differences between two systems of record.

  • Rethinking Testing
    1 project | /r/ProgrammingLanguages | 11 Aug 2022
    As far as this idea, I have seen this before in a few different forms. The closest thing that I've personally witnessed being used is the scientist gem for Ruby applications. You have to do it manually, but you can instrument your code to compare old and new versions of some code. It also does some fancy stuff like randomly choosing which version gets run, almost like an A/B test. I wonder if there's a similar library for Python?
  • axum-strangler initial release
    1 project | /r/rust | 19 Jul 2022
    Not sure what OP had in mind, but for my dream strangler (that's a phrase I never expected to use), I'd love functionality like github's scientist library; basically, the ability to implement a route, continue to serve most requests through the original service, but duplicate a small percentage to the new implementation, compare the outputs of the two services, and log wherever the responses differ, so you get live production tests to exercise the new service without impacting users.
  • Using Scientist to Refactor Critical Ruby on Rails Code
    3 projects | | 25 May 2022
    However, the good news is that it’s easy and safe to do so in Ruby and Rails using the Scientist gem. Scientist's name is based on the scientific method of conducting experiments to verify a given hypothesis. In this case, our hypothesis is that the new code does the job.
  • Book notes: Turn the Ship Around!
    6 projects | | 4 May 2022
    Github scientist.

What are some alternatives?

When comparing Rubocop and Scientist you can also consider the following projects:

Rubycritic - A Ruby code quality reporter

Coverband - Ruby production code coverage collection and reporting (line of code usage)

Brakeman - A static analysis security vulnerability scanner for Ruby on Rails applications

SimpleCov - Code coverage for Ruby with a powerful configuration library and automatic merging of coverage across test suites

Reek - Code smell detector for Ruby

Pronto - Quick automated code review of your changes

Traceroute - A Rake task gem that helps you find the unused routes and controller actions for your Rails 3+ app

rails_best_practices - a code metric tool for rails projects

Flog - Flog reports the most tortured code in an easy to read pain report. The higher the score, the more pain the code is in.

bundler-leak - Known-leaky gems verification for bundler: `bundle leak` to check your app and find leaky gems in your Gemfile :gem::droplet: