Merge pull request #891 from AlexWayfer/disable_RSpec/DescribeClass_for_string_constants

Ignore String constants by `RSpec/Describe`

Author: bquorning

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,6 +7,7 @@ Before submitting the PR make sure the following are checked:
 * [ ] Feature branch is up-to-date with `master` (if not - rebase it).
 * [ ] Squashed related commits together.
 * [ ] Added tests.
+* [ ] Updated documentation.
 * [ ] Added an entry to the [changelog](https://github.com/rubocop-hq/rubocop-rspec/blob/master/CHANGELOG.md) if the new code introduces user-observable changes.
 * [ ] The build (`bundle exec rake`) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).
 

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Fix `RSpec/FilePath` detection when absolute path includes test subject. ([@eitoball][])
 * Add new `Capybara/VisibilityMatcher` cop. ([@aried3r][])
+* Ignore String constants by `RSpec/Describe`. ([@AlexWayfer][])
 
 ## 1.38.1 (2020-02-15)
 
@@ -494,3 +495,4 @@ Compatibility release so users can upgrade RuboCop to 0.51.0. No new features.
 [@elebow]: https://github.com/elebow
 [@eitoball]: https://github.com/eitoball
 [@aried3r]: https://github.com/aried3r
+[@AlexWayfer]: https://github.com/AlexWayfer

lib/rubocop/cop/rspec/describe_class.rb

@@ -12,6 +12,11 @@ module RSpec
       #
       #   # good
       #   describe TestedClass do
+      #     subject { described_class }
+      #   end
+      #
+      #   describe 'TestedClass::VERSION' do
+      #     subject { Object.const_get(self.class.description) }
       #   end
       #
       #   describe "A feature example", type: :feature do
@@ -44,12 +49,20 @@ class DescribeClass < Cop
 
         def_node_matcher :shared_group?, SharedGroups::ALL.block_pattern
 
-        def on_top_level_describe(node, args)
+        def on_top_level_describe(node, (described_value, _))
           return if shared_group?(root_node)
           return if valid_describe?(node)
           return if describe_with_rails_metadata?(node)
+          return if string_constant_describe?(described_value)
+
+          add_offense(described_value)
+        end
+
+        private
 
-          add_offense(args.first)
+        def string_constant_describe?(described_value)
+          described_value.str_type? &&
+            described_value.value =~ /^((::)?[A-Z]\w*)+$/
         end
       end
     end

manual/cops_rspec.md

@@ -333,6 +333,11 @@ end
 
 # good
 describe TestedClass do
+  subject { described_class }
+end
+
+describe 'TestedClass::VERSION' do
+  subject { Object.const_get(self.class.description) }
 end
 
 describe "A feature example", type: :feature do

spec/rubocop/cop/rspec/describe_class_spec.rb

@@ -51,6 +51,75 @@
     RUBY
   end
 
+  context 'when argument is a String literal' do
+    it 'ignores class without namespace' do
+      expect_no_offenses(<<-RUBY)
+        describe 'Thing' do
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'ignores class with namespace' do
+      expect_no_offenses(<<-RUBY)
+        describe 'Some::Thing' do
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'ignores value constants' do
+      expect_no_offenses(<<-RUBY)
+        describe 'VERSION' do
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'ignores value constants with namespace' do
+      expect_no_offenses(<<-RUBY)
+        describe 'Some::VERSION' do
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'ignores top-level constants with `::` at start' do
+      expect_no_offenses(<<-RUBY)
+        describe '::Some::VERSION' do
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'checks `camelCase`' do
+      expect_offense(<<-RUBY)
+        describe 'activeRecord' do
+                 ^^^^^^^^^^^^^^ The first argument to describe should be the class or module being tested.
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'checks numbers at start' do
+      expect_offense(<<-RUBY)
+        describe '2Thing' do
+                 ^^^^^^^^ The first argument to describe should be the class or module being tested.
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+
+    it 'checks empty strings' do
+      expect_offense(<<-RUBY)
+        describe '' do
+                 ^^ The first argument to describe should be the class or module being tested.
+          subject { Object.const_get(self.class.description) }
+        end
+      RUBY
+    end
+  end
+
   it 'ignores request specs' do
     expect_no_offenses(<<-RUBY)
       describe 'my new feature', type: :request do