Add new RSpec/VariableDefinition cop

Closes #908

Also refactor common matcher into a module & change
`RSpec/VariableName` cop to consider interpolated
strings & symbols (they are parsed as `dsym` & `dstr` nodes).

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Master (Unreleased)
 
 * Add new `RSpec/VariableName` cop. ([@tejasbubane][])
+* Add new `RSpec/VariableDefinition` cop. ([@tejasbubane][])
 
 ## 1.39.0 (2020-05-01)
 

config/default.yml

@@ -454,8 +454,18 @@ RSpec/UnspecifiedException:
   Enabled: true
   StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/UnspecifiedException
 
+RSpec/VariableDefinition:
+  Description: Checks that memoized helpers names are symbols or strings.
+  Enabled: true
+  EnforcedStyle: symbols
+  SupportedStyles:
+  - symbols
+  - strings
+  VersionAdded: '1.40'
+  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/VariableDefinition
+
 RSpec/VariableName:
-  Description: This cop makes sure that all variables use the configured style.
+  Description: Checks that memoized helper names use the configured style.
   Enabled: true
   EnforcedStyle: snake_case
   SupportedStyles:

lib/rubocop-rspec.rb

@@ -17,6 +17,7 @@
 require_relative 'rubocop/rspec/example_group'
 require_relative 'rubocop/rspec/example'
 require_relative 'rubocop/rspec/hook'
+require_relative 'rubocop/rspec/variable'
 require_relative 'rubocop/cop/rspec/cop'
 require_relative 'rubocop/rspec/align_let_brace'
 require_relative 'rubocop/rspec/factory_bot'

lib/rubocop/cop/rspec/variable_definition.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      # Checks that memoized helpers names are symbols or strings.
+      #
+      # @example EnforcedStyle: symbols (default)
+      #   # bad
+      #   let('user_name') { 'Adam' }
+      #   subject('user') { create_user }
+      #
+      #   # good
+      #   let(:user_name) { 'Adam' }
+      #   subject(:user) { create_user }
+      #
+      # @example EnforcedStyle: strings
+      #   # bad
+      #   let(:user_name) { 'Adam' }
+      #   subject(:user) { create_user }
+      #
+      #   # good
+      #   let('user_name') { 'Adam' }
+      #   subject('user') { create_user }
+      class VariableDefinition < Cop
+        include ConfigurableEnforcedStyle
+        include RuboCop::RSpec::Variable
+
+        MSG = 'Use %<style>s for variable names.'
+
+        def on_send(node)
+          variable_definition?(node) do |variable|
+            if style_violation?(variable)
+              add_offense(variable, message: format(MSG, style: style))
+            end
+          end
+        end
+
+        private
+
+        def style_violation?(variable)
+          style == :symbols && string?(variable) ||
+            style == :strings && symbol?(variable)
+        end
+
+        def string?(node)
+          node.str_type? || node.dstr_type?
+        end
+
+        def symbol?(node)
+          node.sym_type? || node.dsym_type?
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rspec/variable_name.rb

@@ -3,7 +3,7 @@
 module RuboCop
   module Cop
     module RSpec
-      # This cop makes sure that all variables use the configured style.
+      # Checks that memoized helper names use the configured style.
       #
       # @example EnforcedStyle: snake_case (default)
       #   # bad
@@ -24,16 +24,14 @@ module RSpec
       #   subject(:userName) { 'Adam' }
       class VariableName < Cop
         include ConfigurableNaming
+        include RuboCop::RSpec::Variable
 
         MSG = 'Use %<style>s for variable names.'
 
-        def_node_matcher :variable_definition?, <<~PATTERN
-          (send #{RSPEC} #{(Helpers::ALL + Subject::ALL).node_pattern_union}
-            $({sym str} _) ...)
-        PATTERN
-
         def on_send(node)
           variable_definition?(node) do |variable|
+            return if variable.dstr_type? || variable.dsym_type?
+
             check_name(node, variable.value, variable.loc.expression)
           end
         end

lib/rubocop/cop/rspec_cops.rb

@@ -86,6 +86,7 @@
 require_relative 'rspec/single_argument_message_chain'
 require_relative 'rspec/subject_stub'
 require_relative 'rspec/unspecified_exception'
+require_relative 'rspec/variable_definition'
 require_relative 'rspec/variable_name'
 require_relative 'rspec/verified_doubles'
 require_relative 'rspec/void_expect'

lib/rubocop/rspec/variable.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module RSpec
+    # Helps check offenses with variable definitions
+    module Variable
+      include Language
+      extend RuboCop::NodePattern::Macros
+
+      def_node_matcher :variable_definition?, <<~PATTERN
+        (send #{RSPEC} #{(Helpers::ALL + Subject::ALL).node_pattern_union}
+          $({sym str dsym dstr} ...) ...)
+      PATTERN
+    end
+  end
+end

manual/cops.md

@@ -85,6 +85,7 @@
 * [RSpec/SingleArgumentMessageChain](cops_rspec.md#rspecsingleargumentmessagechain)
 * [RSpec/SubjectStub](cops_rspec.md#rspecsubjectstub)
 * [RSpec/UnspecifiedException](cops_rspec.md#rspecunspecifiedexception)
+* [RSpec/VariableDefinition](cops_rspec.md#rspecvariabledefinition)
 * [RSpec/VariableName](cops_rspec.md#rspecvariablename)
 * [RSpec/VerifiedDoubles](cops_rspec.md#rspecverifieddoubles)
 * [RSpec/VoidExpect](cops_rspec.md#rspecvoidexpect)

manual/cops_rspec.md

@@ -3013,13 +3013,57 @@ expect { do_something }.not_to raise_error
 
 * [https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/UnspecifiedException](https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/UnspecifiedException)
 
+## RSpec/VariableDefinition
+
+Enabled by default | Supports autocorrection
+--- | ---
+Enabled | No
+
+Checks that memoized helpers names are symbols or strings.
+
+### Examples
+
+#### EnforcedStyle: symbols (default)
+
+```ruby
+# bad
+let('user_name') { 'Adam' }
+subject('user') { create_user }
+
+# good
+let(:user_name) { 'Adam' }
+subject(:user) { create_user }
+```
+#### EnforcedStyle: strings
+
+```ruby
+# bad
+let(:user_name) { 'Adam' }
+subject(:user) { create_user }
+
+# good
+let('user_name') { 'Adam' }
+subject('user') { create_user }
+```
+
+### Configurable attributes
+
+Name | Default value | Configurable values
+--- | --- | ---
+EnforcedStyle | `symbols` | `symbols`, `strings`
+VersionAdded | `1.40` | String
+
+### References
+
+* [https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/VariableDefinition](https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/VariableDefinition)
+
 ## RSpec/VariableName
 
 Enabled by default | Supports autocorrection
 --- | ---
 Enabled | No
 
-This cop makes sure that all variables use the configured style.
+Checks that memoized helper names use the configured style.
 
 ### Examples
 

spec/rubocop/cop/rspec/variable_definition_spec.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::RSpec::VariableDefinition, :config do
+  subject(:cop) { described_class.new(config) }
+
+  context 'when EnforcedStyle is `symbols`' do
+    let(:cop_config) { { 'EnforcedStyle' => 'symbols' } }
+
+    it 'registers an offense for string name' do
+      expect_offense(<<~RUBY)
+        let("user_name") { 'Adam' }
+            ^^^^^^^^^^^ Use symbols for variable names.
+      RUBY
+    end
+
+    it 'registers an offense for interpolated string' do
+      expect_offense(<<~'RUBY')
+        let("user-#{id}") { 'Adam' }
+            ^^^^^^^^^^^^ Use symbols for variable names.
+      RUBY
+    end
+
+    it 'registers an offense for multiline string' do
+      expect_offense(<<~'RUBY')
+        let("user"\
+            ^^^^^^^ Use symbols for variable names.
+            "-foo") { 'Adam' }
+      RUBY
+    end
+
+    it 'does not register offense for symbol names' do
+      expect_no_offenses(<<~RUBY)
+        let(:user_name) { 'Adam' }
+      RUBY
+    end
+  end
+
+  context 'when EnforcedStyle is `strings`' do
+    let(:cop_config) { { 'EnforcedStyle' => 'strings' } }
+
+    it 'registers an offense for symbol name' do
+      expect_offense(<<~RUBY)
+        let(:user_name) { 'Adam' }
+            ^^^^^^^^^^ Use strings for variable names.
+      RUBY
+    end
+
+    it 'registers an offense for interpolated symbol' do
+      expect_offense(<<~'RUBY')
+        let(:"user-#{id}") { 'Adam' }
+            ^^^^^^^^^^^^^ Use strings for variable names.
+      RUBY
+    end
+
+    it 'does not register offense for string names' do
+      expect_no_offenses(<<~RUBY)
+        let("user_name") { 'Adam' }
+      RUBY
+    end
+  end
+end

spec/rubocop/cop/rspec/variable_name_spec.rb

@@ -36,6 +36,12 @@
           let(:user_name) { 'Adam' }
         RUBY
       end
+
+      it 'does not register offense for interpolated symbol' do
+        expect_no_offenses(<<~'RUBY')
+          let(:"user#{name}") { 'Adam' }
+        RUBY
+      end
     end
 
     context 'when `let` with string names' do
@@ -58,6 +64,12 @@
           let('user_name') { 'Adam' }
         RUBY
       end
+
+      it 'does not register offense for interpolated string' do
+        expect_no_offenses(<<~'RUBY')
+          let("user#{name}") { 'Adam' }
+        RUBY
+      end
     end
 
     context 'when `let` with proc' do