[Fix #7669] Add Bundler/GemVersion cop

changelog/new_gem_version_declaration.md

@@ -0,0 +1 @@
+* [#7669](https://github.com/rubocop/rubocop/issues/7669): New cop `Bundler/GemVersionDeclaration` requires or prohibits specifying gem versions. ([@timlkelly][])

config/default.yml

@@ -174,6 +174,18 @@ Bundler/GemComment:
   IgnoredGems: []
   OnlyFor: []
 
+Bundler/GemVersionDeclaration:
+  Description: 'Requires or prohibits gem version declarations.'
+  Enabled: false
+  VersionAdded: '<<next>>'
+  EnforcedStyle: 'required'
+  SupportedStyles:
+    - 'required'
+    - 'prohibited'
+  Include:
+    - '**/Gemfile'
+  IgnoredGems: []
+
 Bundler/InsecureProtocolSource:
   Description: >-
                  The source `:gemcutter`, `:rubygems` and `:rubyforge` are deprecated

lib/rubocop.rb

@@ -148,6 +148,7 @@
 
 require_relative 'rubocop/cop/bundler/duplicated_gem'
 require_relative 'rubocop/cop/bundler/gem_comment'
+require_relative 'rubocop/cop/bundler/gem_version_declaration'
 require_relative 'rubocop/cop/bundler/insecure_protocol_source'
 require_relative 'rubocop/cop/bundler/ordered_gems'
 

lib/rubocop/cop/bundler/gem_version_declaration.rb

@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Bundler
+      # Enforce that Gem version declarations are either required
+      # or prohibited.
+      #
+      # @example EnforcedStyle: required (default)
+      #  # bad
+      #  gem 'rubocop'
+      #
+      #  # good
+      #  gem 'rubocop', '~> 1.12'
+      #
+      #  # good
+      #  gem 'rubocop', '>= 1.10.0'
+      #
+      #  # good
+      #  gem 'rubocop', '>= 1.5.0', '< 1.10.0'
+      #
+      # @example EnforcedStyle: prohibited
+      #  # good
+      #  gem 'rubocop'
+      #
+      #  # bad
+      #  gem 'rubocop', '~> 1.12'
+      #
+      #  # bad
+      #  gem 'rubocop', '>= 1.10.0'
+      #
+      #  # bad
+      #  gem 'rubocop', '>= 1.5.0', '< 1.10.0'
+      #
+      class GemVersionDeclaration < Base
+        include ConfigurableEnforcedStyle
+
+        REQUIRED_MSG = 'Gem version declaration is required.'
+        PROHIBITED_MSG = 'Gem version declaration is prohibited.'
+        VERSION_DECLARATION_REGEX = /^[~<>=]*\s?[0-9.]+/.freeze
+
+        # @!method gem_declaration?(node)
+        def_node_matcher :gem_declaration?, '(send nil? :gem str ...)'
+
+        # @!method includes_version_declaration?(node)
+        def_node_matcher :includes_version_declaration?, <<~PATTERN
+          (send nil? :gem <(str #version_declaration?) ...>)
+        PATTERN
+
+        def on_send(node)
+          return unless gem_declaration?(node)
+          return if ignored_gem?(node)
+
+          if offense?(node)
+            add_offense(node)
+            opposite_style_detected
+          else
+            correct_style_detected
+          end
+        end
+
+        private
+
+        def ignored_gem?(node)
+          ignored_gems.include?(node.first_argument.value)
+        end
+
+        def ignored_gems
+          Array(cop_config['IgnoredGems'])
+        end
+
+        def message(range)
+          gem_declaration = range.source
+
+          if required_style?
+            format(REQUIRED_MSG, gem_declaration: gem_declaration)
+          elsif prohibited_style?
+            format(PROHIBITED_MSG, gem_declaration: gem_declaration)
+          end
+        end
+
+        def offense?(node)
+          (required_style? && !includes_version_declaration?(node)) ||
+            (prohibited_style? && includes_version_declaration?(node))
+        end
+
+        def prohibited_style?
+          style == :prohibited
+        end
+
+        def required_style?
+          style == :required
+        end
+
+        def version_declaration?(expression)
+          expression.match?(VERSION_DECLARATION_REGEX)
+        end
+      end
+    end
+  end
+end

spec/rubocop/cop/bundler/gem_version_declaration_spec.rb

@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Bundler::GemVersionDeclaration, :config do
+  context 'when EnforcedStyle is set to required (default)' do
+    let(:cop_config) do
+      {
+        'EnforcedStyle' => 'required',
+        'IgnoredGems' => ['rspec']
+      }
+    end
+
+    it 'flags gems without a version declaration' do
+      expect_offense(<<~RUBY)
+        gem 'rubocop'
+        ^^^^^^^^^^^^^ Gem version declaration is required.
+        gem 'rubocop', require: false
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Gem version declaration is required.
+      RUBY
+    end
+
+    it 'ignores gems with a declared version' do
+      expect_no_offenses(<<~RUBY)
+        gem 'rubocop', '>=1.10.0'
+        gem 'rubocop', '~> 1'
+        gem 'rubocop', '~> 1.12', require: false
+        gem 'rubocop', '>= 1.5.0', '< 1.10.0', git: 'https://github.com/rubocop/rubocop'
+      RUBY
+    end
+
+    it 'ignores gems included in IgnoredGems metadata' do
+      expect_no_offenses(<<~RUBY)
+        gem 'rspec'
+      RUBY
+    end
+  end
+
+  context 'when EnforcedStyle is set to prohibited' do
+    let(:cop_config) do
+      {
+        'EnforcedStyle' => 'prohibited',
+        'IgnoredGems' => ['rspec']
+      }
+    end
+
+    it 'flags gems with a version declaration' do
+      expect_offense(<<~RUBY)
+        gem 'rubocop', '~> 1'
+        ^^^^^^^^^^^^^^^^^^^^^ Gem version declaration is prohibited.
+        gem 'rubocop', '>=1.10.0'
+        ^^^^^^^^^^^^^^^^^^^^^^^^^ Gem version declaration is prohibited.
+        gem 'rubocop', '~> 1.12', require: false
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Gem version declaration is prohibited.
+        gem 'rubocop', '>= 1.5.0', '< 1.10.0', git: 'https://github.com/rubocop/rubocop'
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Gem version declaration is prohibited.
+      RUBY
+    end
+
+    it 'ignores gems without a declared version' do
+      expect_no_offenses(<<~RUBY)
+        gem 'rubocop'
+        gem 'rubocop', require: false
+      RUBY
+    end
+
+    it 'ignores gems included in IgnoredGems metadata' do
+      expect_no_offenses(<<~RUBY)
+        gem 'rspec', '~> 3.10'
+      RUBY
+    end
+  end
+end