rubocop-avoid_unless

A RuboCop extension that bans unless in favor of if with an inverse or negated condition. It provides a single cop, Style/AvoidUnless, with full auto-correction support.

Why

unless can harm readability, especially with compound or negated conditions (unless !done?, unless x && y). This cop enforces a consistent if-only style across your codebase.

Installation

Add the gem to your Gemfile or gemspec:

gem "rubocop-avoid_unless"

Then run bundle install.

Setup

With Standard Ruby

If you use Standard Ruby, add the plugin to your .standard.yml:

plugins:
  - rubocop-avoid_unless

Standard will load the cop automatically via the lint_roller plugin system. No other configuration is needed.

With RuboCop directly

If you use RuboCop without Standard, there are two options:

Option A - Use the lint_roller plugin system (RuboCop 1.72+). Add to your .rubocop.yml:

plugins:
  - rubocop-avoid_unless

Option B - Use the traditional require approach. Add to your .rubocop.yml:

require:
  - rubocop-avoid_unless

Configuration

The cop is enabled by default once loaded. To disable or customize it, add to your .rubocop.yml:

Style/AvoidUnless:
  Enabled: false

How it works

The cop flags every use of unless (both modifier and block forms) and auto-corrects to if by inverting the condition:

# bad
do_something unless items.any?
return unless value.present?
return unless condition

# good (auto-corrected)
do_something if items.none?
return if value.blank?
return if !condition

It handles:

• Inverse methods - any?/none?, present?/blank?, include?/exclude?, even?/odd?, etc.
• Inverse operators - ==/!=, >/<=, =~/!~, etc.
• Double negation removal - unless !x becomes if x
• De Morgan's law - unless a && b becomes if !a || !b

Requirements

• Ruby >= 3.2
• RuboCop >= 1.72

License

MIT