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Standard - Ruby style guide, linter, and formatter

Tests Ruby Style Guide Gem Version

This gem is a spiritual port of StandardJS and aims to save you (and others!) time in the same three ways:

  • No configuration. The easiest way to enforce consistent style in your project. Just drop it in.
  • Automatically format code. Just run standardrb --fix and say goodbye to messy or inconsistent code.
  • Catch style issues & programmer errors early. Save precious code review time by eliminating back-and-forth between reviewer & contributor.

No decisions to make. It just works. Here's a lightning talk about it.

Install by adding it to your Gemfile:

gem "standard", group: [:development, :test]

And running bundle install.

Run Standard from the command line with:

$ bundle exec standardrb

And if you'd like, Standard can autocorrect your code by tacking on a --fix flag.

StandardRB — The Rules

  • 2 spaces – for indentation
  • Double quotes for string literals - because pre-committing to whether you'll need interpolation in a string slows people down
  • 1.9 hash syntax - When all the keys in a hash literal are symbols, Standard enforces Ruby 1.9's {hash: syntax}
  • Braces for single-line blocks - Require {/} for one-line blocks, but allow either braces or do/end for multiline blocks. Like using do/end for multiline blocks? Prefer {/} when chaining? A fan of expressing intent with Jim Weirich's semantic block approach? Standard lets you do you!
  • Leading dots on multi-line method chains - chosen for these reasons.
  • Spaces inside blocks, but not hash literals - In Ruby, the { and } characters do a lot of heavy lifting. To visually distinguish hash literals from blocks, Standard enforces that (like arrays), no leading or trailing spaces be added to pad hashes
  • And a good deal more

If you're familiar with RuboCop, you can look at Standard's current base configuration in config/base.yml. In lieu of a separate changelog file, significant changes to the configuration will be documented as GitHub release notes.


Once you've installed Standard, you should be able to use the standardrb program. The simplest use case would be checking the style of all Ruby files in the current working directory:

$ bundle exec standardrb
standard: Use Ruby Standard Style (
standard: Run `standardrb --fix` to automatically fix some problems.
  /Users/code/cli.rb:31:23: Style/Semicolon: Do not use semicolons to terminate expressions.

You can optionally pass in a directory (or directories) using the glob pattern. Be sure to quote paths containing glob patterns so that they are expanded by standardrb instead of your shell:

$ bundle exec standardrb "lib/**/*.rb" test

Note: by default, StandardRB will look for all *.rb files (and some other files typically associated with Ruby like *.gemspec and Gemfile)

If you have an existing project but aren't ready to fix all the files yet you can generate a todo file:

$ bundle exec standardrb --generate-todo

This will create a .standard_todo.yml that lists all the files that contain errors. When you run Standard in the future it will ignore these files as if they lived under the ignore section in the .standard.yml file.

As you refactor your existing project you can remove files from the list. You can also regenerate the todo file at any time by re-running the above command.

Using with Rake

Standard also ships with Rake tasks. If you're using Rails, these should autoload and be available after installing Standard. Otherwise, just require the tasks in your Rakefile:

require "standard/rake"

Here are the tasks bundled with Standard:

$ rake standard     # equivalent to running `standardrb`
$ rake standard:fix # equivalent to running `standardrb --fix`

You may also pass command line options to Standard's Rake tasks by embedding them in a STANDARDOPTS environment variable (similar to how the Minitest Rake task accepts CLI options in TESTOPTS).

# equivalent to `standardrb --format progress`:
$ rake standard STANDARDOPTS="--format progress"

# equivalent to `standardrb lib "app/**/*"`, to lint just certain paths:
$ rake standard STANDARDOPTS="lib \"app/**/*\""

What you might do if you're clever

If you want or need to configure Standard, there are a handful of options available by creating a .standard.yml file in the root of your project.

Here's an example yaml file with every option set:

fix: true               # default: false
parallel: true          # default: false
format: progress        # default: Standard::Formatter
ruby_version: 2.3.3     # default: RUBY_VERSION
default_ignores: false  # default: true

ignore:                 # default: []
  - 'db/schema.rb'
  - 'vendor/**/*'
  - 'test/**/*':
    - Layout/AlignHash

Note: If you're running Standard in a context where your .standard.yml file cannot be found by ascending the current working directory (i.e., against a temporary file buffer in your editor), you can specify the config location with --config path/to/.standard.yml.

Similarly, for the .standard_todo.yml file, you can specify --todo path/to/.standard_todo.yml.

What you might do if you're REALLY clever

Because StandardRB is essentially a wrapper on top of RuboCop, it will actually forward the vast majority of CLI and ENV arguments to RuboCop.

You can see a list of RuboCop's CLI flags here.

Why should I use Ruby Standard Style?

(This section will look familiar if you've used StandardJS.)

The beauty of Ruby Standard Style is that it's simple. No one wants to maintain multiple hundred-line style configuration files for every module/project they work on. Enough of this madness!

This gem saves you (and others!) time in three ways:

  • No configuration. The easiest way to enforce consistent style in your project. Just drop it in.
  • Automatically format code. Just run standardrb --fix and say goodbye to messy or inconsistent code.
  • Catch style issues & programmer errors early. Save precious code review time by eliminating back-and-forth between reviewer & contributor.

Adopting Standard style means ranking the importance of code clarity and community conventions higher than personal style. This might not make sense for 100% of projects and development cultures, however open source can be a hostile place for newbies. Setting up clear, automated contributor expectations makes a project healthier.

Who uses Ruby Standard Style?

(This section will not look very familiar if you've used StandardJS.)

If your team starts using Standard, send a pull request to let us know!

Is there a readme badge?

Yes! If you use Standard in your project, you can include one of these badges in your readme to let people know that your code is using the StandardRB style.

Ruby Style Guide

[![Ruby Style Guide](](

I disagree with rule X, can you change it?

No. The whole point of Standard is to save you time by avoiding bikeshedding about code style. There are lots of debates online about tabs vs. spaces, etc. that will never be resolved. These debates just distract from getting stuff done. At the end of the day you have to 'just pick something', and that's the whole philosophy of Standard -- it's a bunch of sensible 'just pick something' opinions. Hopefully, users see the value in that over defending their own opinions.

Pro tip: Just use Standard and move on. There are actual real problems that you could spend your time solving! :P

Is there an automatic formatter?

Yes! You can use standardrb --fix to fix most issues automatically.

standardrb --fix is built into standardrb for maximum convenience. Most problems are fixable, but some errors must be fixed manually.

Can I override the fix: true config setting?

Also yes! You can use standardrb --no-fix. Not fixing is the default behavior, but this flag will override the fix: true setting in your .standard.yml config. This is especially useful for checking your project's compliance with standardrb in CI environments while keeping the fix: true option enabled locally.

How do I ignore files?

Sometimes you need to ignore additional folders or specific minified files. To do that, add a .standard.yml file to the root of your project and specify a list of files and globs that should be excluded:

  - 'some/file/in/particular.rb'
  - 'a/whole/directory/**/*'

You can see the files Standard ignores by default here

How do I hide a certain warning?

In rare cases, you'll need to break a rule and hide the warning generated by Standard.

Ruby Standard Style uses RuboCop under-the-hood and you can hide warnings as you normally would if you used RuboCop directly.

To ignore only certain rules from certain globs (not recommended, but maybe your test suite uses a non-standardable DSL, you can specify an array of RuboCop rules to ignore for a particular glob:

  - 'test/**/*':
    - Layout/EndAlignment

How do I disable a warning within my source code?

You can also use special comments to disable all or certain rules within your source code.

Given this source listing foo.rb:

baz = 42

Running standard foo.rb would fail:

foo.rb:1:1: Lint/UselessAssignment: Useless assignment to variable - `baz`.

If we wanted to make an exception, we could add the following comment:

baz = 42 # standard:disable Lint/UselessAssignment

The comment directives (both standard:disable and rubocop:disable) will suppress the error and Standard would succeed.

If, however, you needed to disable standard for multiple lines, you could use open and closing directives like this:

# standard:disable Layout/IndentationWidth
def foo
# standard:enable Layout/IndentationWidth

And if you don't know or care which rule is being violated, you can also substitute its name for "all". This line actually triggers three different violations, so we can suppress them like this:

baz = ['a'].each do end # standard:disable all

How do I specify a Ruby version? What is supported?

Because Standard wraps RuboCop, they share the same runtime requirements—currently, that's MRI 2.3 and newer. While Standard can't avoid this runtime requirement, it does allow you to lint codebases that target Ruby versions older than 2.3 by narrowing the ruleset somewhat.

Standard will default to telling RuboCop to target the currently running version of Ruby (by inspecting RUBY_VERSION at runtime. But if you want to lock it down, you can specify ruby_version in .standard.yml.

ruby_version: 1.8.7

See testdouble/suture for an example.

It's a little confusing to consider, but the targeted Ruby version for linting may or may not match the version of the runtime (suppose you're on Ruby 2.5.1, but your library supports Ruby 2.3.0). In this case, specify ruby_version and you should be okay. However, note that if you target a newer Ruby version than the runtime, RuboCop may behave in surprising or inconsistent ways.

If you are targeting a Ruby older than 2.3 and run into an issue, check out Standard's version-specific RuboCop configurations and consider helping out by submitting a pull request if you find a rule that won't work for older Rubies.

How do I change the output?

Standard's built-in formatter is intentionally minimal, printing only unfixed failures or (when successful) printing nothing at all. If you'd like to use a different formatter, you can specify any of RuboCop's built-in formatters or write your own.

For example, if you'd like to see colorful progress dots, you can either run Standard with:

$ bundle exec standardrb --format progress
Inspecting 15 files

15 files inspected, no offenses detected

Or, in your project's .standard.yml file, specify:

format: progress

Refer to RuboCop's documentation on formatters for more information.

How do I run Standard in my editor?

It can be very handy to know about failures while editing to shorten the feedback loop. Some editors support asynchronously running linters.

How do I use Standard with Rubocop extensions?

This is not officially supported by Standard. However, Evil Martians wrote up a regularly updated guide on how to do so.

Does Standard work with [Insert other tool name here]?

Maybe! Start by searching the repository to see if there's an existing issue open for the tool you're interested in. That aside, here are other known integrations aside from editor plugins:


Follow the steps below to setup standard locally:

$ git clone
$ cd standard
$ gem install bundler # if working with ruby version below 2.6.0
$ bundle install
$ bundle exec rake # to run test suite

Code of Conduct

This project follows Test Double's code of conduct for all community interactions, including (but not limited to) one-on-one communications, public posts/comments, code reviews, pull requests, and GitHub issues. If violations occur, Test Double will take any action they deem appropriate for the infraction, up to and including blocking a user from the organization's repositories.