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rubocop · Jun 13, 2020 · 5d51ade · 5d51ade
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diff --git a/config/default.yml b/config/default.yml
@@ -347,6 +347,13 @@ RSpec/LetSetup:
   VersionAdded: '1.7'
   StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/LetSetup
 
+RSpec/MemoizedHelpersInExampleGroup:
+  Description: Checks for over-usage of `let` and `subject` blocks in example groups.
+  Enabled: false
+  AllowSubject: false
+  Max: 5
+  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup
+
 RSpec/MessageChain:
   Description: Check that chains of messages are not being stubbed.
   Enabled: true
@@ -415,12 +422,6 @@ RSpec/NestedGroups:
   VersionChanged: '1.10'
   StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NestedGroups
 
-RSpec/MemoizedHelpersInExampleGroup:
-  Description: Checks for usage of `let` blocks in specs.
-  Enabled: false
-  AllowSubject: false
-  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup
-
 RSpec/NotToNot:
   Description: Checks for consistent method usage for negating expectations.
   Enabled: true

diff --git a/lib/rubocop/cop/rspec/memoized_helpers_in_example_group.rb b/lib/rubocop/cop/rspec/memoized_helpers_in_example_group.rb
@@ -3,8 +3,9 @@
 module RuboCop
   module Cop
     module RSpec
-      # Checks for usage of `let` blocks in specs.
+      # Checks for over-usage of `let` and `subject` blocks in example groups.
       #
+      # The maximum count can be configured.
       # This cop can be configured with the option `AllowSubject` which
       # will configure the cop to only register offenses on explicit calls to
       # `let` and not calls to `subject`
@@ -55,22 +56,35 @@ module RSpec
       #   end
       #
       class MemoizedHelpersInExampleGroup < Cop
-        MSG = 'Avoid using `%<method>s` ' \
-              '– use a method call or local variable instead.'
+        MSG = 'Too many memoized helpers used. [%<count>d/%<max>d]'
 
-        def_node_matcher :let?, Helpers::ALL.send_pattern
-        def_node_matcher :subject?, Subject::ALL.send_pattern
+        def on_block(node)
+          return unless example_group?(node)
 
-        def on_send(node)
-          if subject?(node) && !allow_subject?
-            add_offense(node, message: format(MSG, method: 'subject'))
-          elsif let?(node)
-            add_offense(node, message: format(MSG, method: 'let'))
+          count = count_helpers(node)
+
+          node.each_ancestor(:block) do |ancestor|
+            count += count_helpers(ancestor)
           end
+
+          return if count <= max
+
+          add_offense(node, message: format(MSG, count: count, max: max))
         end
 
         private
 
+        def count_helpers(node)
+          example_group = RuboCop::RSpec::ExampleGroup.new(node)
+          count = example_group.lets.count
+          count += example_group.subjects.count unless allow_subject?
+          count
+        end
+
+        def max
+          cop_config['Max']
+        end
+
         def allow_subject?
           cop_config['AllowSubject']
         end

diff --git a/lib/rubocop/cop/rspec_cops.rb b/lib/rubocop/cop/rspec_cops.rb
@@ -59,6 +59,7 @@
 require_relative 'rspec/leaky_constant_declaration'
 require_relative 'rspec/let_before_examples'
 require_relative 'rspec/let_setup'
+require_relative 'rspec/memoized_helpers_in_example_group'
 require_relative 'rspec/message_chain'
 require_relative 'rspec/message_expectation'
 require_relative 'rspec/message_spies'
@@ -68,7 +69,6 @@
 require_relative 'rspec/multiple_subjects'
 require_relative 'rspec/named_subject'
 require_relative 'rspec/nested_groups'
-require_relative 'rspec/no_let'
 require_relative 'rspec/not_to_not'
 require_relative 'rspec/overwriting_setup'
 require_relative 'rspec/pending'

diff --git a/lib/rubocop/rspec/example_group.rb b/lib/rubocop/rspec/example_group.rb
@@ -14,6 +14,10 @@ class ExampleGroup < Concept
         ExampleGroups::ALL + SharedGroups::ALL + Includes::ALL
       ).block_pattern
 
+      def lets
+        lets_in_scope(node)
+      end
+
       def subjects
         subjects_in_scope(node)
       end
@@ -34,6 +38,12 @@ def subjects_in_scope(node)
         end
       end
 
+      def lets_in_scope(node)
+        node.each_child_node.flat_map do |child|
+          find_lets(child)
+        end
+      end
+
       def find_subjects(node)
         return [] if scope_change?(node)
 
@@ -44,6 +54,16 @@ def find_subjects(node)
         end
       end
 
+      def find_lets(node)
+        return [] if scope_change?(node)
+
+        if let?(node)
+          [node]
+        else
+          lets_in_scope(node)
+        end
+      end
+
       def hooks_in_scope(node)
         node.each_child_node.flat_map do |child|
           find_hooks(child)

diff --git a/manual/cops.md b/manual/cops.md
@@ -58,6 +58,7 @@
 * [RSpec/LeakyConstantDeclaration](cops_rspec.md#rspecleakyconstantdeclaration)
 * [RSpec/LetBeforeExamples](cops_rspec.md#rspecletbeforeexamples)
 * [RSpec/LetSetup](cops_rspec.md#rspecletsetup)
+* [RSpec/MemoizedHelpersInExampleGroup](cops_rspec.md#rspecmemoizedhelpersinexamplegroup)
 * [RSpec/MessageChain](cops_rspec.md#rspecmessagechain)
 * [RSpec/MessageExpectation](cops_rspec.md#rspecmessageexpectation)
 * [RSpec/MessageSpies](cops_rspec.md#rspecmessagespies)
@@ -67,7 +68,6 @@
 * [RSpec/MultipleSubjects](cops_rspec.md#rspecmultiplesubjects)
 * [RSpec/NamedSubject](cops_rspec.md#rspecnamedsubject)
 * [RSpec/NestedGroups](cops_rspec.md#rspecnestedgroups)
-* [RSpec/MemoizedHelpersInExampleGroup](cops_rspec.md#rspecnolet)
 * [RSpec/NotToNot](cops_rspec.md#rspecnottonot)
 * [RSpec/OverwritingSetup](cops_rspec.md#rspecoverwritingsetup)
 * [RSpec/Pending](cops_rspec.md#rspecpending)

diff --git a/manual/cops_rspec.md b/manual/cops_rspec.md
@@ -1890,6 +1890,79 @@ end
 
 * [https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/LetSetup](https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/LetSetup)
 
+## RSpec/MemoizedHelpersInExampleGroup
+
+Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+--- | --- | --- | --- | ---
+Disabled | Yes | No | - | -
+
+Checks for over-usage of `let` and `subject` blocks in example groups.
+
+The maximum count can be configured.
+This cop can be configured with the option `AllowSubject` which
+will configure the cop to only register offenses on explicit calls to
+`let` and not calls to `subject`
+
+### Examples
+
+```ruby
+# bad
+describe MyClass do
+  let(:foo) { [] }
+  it { expect(foo).to be_empty }
+end
+
+describe MyClass do
+  subject(:foo) { [] }
+  it { expect(foo).to be_empty }
+end
+
+# good
+describe MyClass do
+  it do
+    foo = []
+    expect(foo).to be_empty
+  end
+end
+```
+#### with AllowSubject configuration
+
+```ruby
+# rubocop.yml
+# RSpec/MemoizedHelpersInExampleGroup:
+#   AllowSubject: true
+
+# bad
+describe MyClass do
+  let(:foo) { [] }
+  it { expect(foo).to be_empty }
+end
+
+# good
+describe MyClass do
+  subject(:foo) { [] }
+  it { expect(foo).to be_empty }
+end
+
+describe MyClass do
+  it do
+    foo = []
+    expect(foo).to be_empty
+  end
+end
+```
+
+### Configurable attributes
+
+Name | Default value | Configurable values
+--- | --- | ---
+AllowSubject | `false` | Boolean
+Max | `5` | Integer
+
+### References
+
+* [https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup](https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup)
+
 ## RSpec/MessageChain
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
@@ -2322,77 +2395,6 @@ Max | `3` | Integer
 
 * [https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NestedGroups](https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NestedGroups)
 
-## RSpec/MemoizedHelpersInExampleGroup
-
-Enabled by default | Supports autocorrection
---- | ---
-Disabled | No
-
-Checks for usage of `let` blocks in specs.
-
-This cop can be configured with the option `AllowSubject` which
-will configure the cop to only register offenses on explicit calls to
-`let` and not calls to `subject`
-
-### Examples
-
-```ruby
-# bad
-describe MyClass do
-  let(:foo) { [] }
-  it { expect(foo).to be_empty }
-end
-
-describe MyClass do
-  subject(:foo) { [] }
-  it { expect(foo).to be_empty }
-end
-
-# good
-describe MyClass do
-  it do
-    foo = []
-    expect(foo).to be_empty
-  end
-end
-```
-#### with AllowSubject configuration
-
-```ruby
-# rubocop.yml
-# RSpec/MemoizedHelpersInExampleGroup:
-#   AllowSubject: true
-
-# bad
-describe MyClass do
-  let(:foo) { [] }
-  it { expect(foo).to be_empty }
-end
-
-# good
-describe MyClass do
-  subject(:foo) { [] }
-  it { expect(foo).to be_empty }
-end
-
-describe MyClass do
-  it do
-    foo = []
-    expect(foo).to be_empty
-  end
-end
-```
-
-### Configurable attributes
-
-Name | Default value | Configurable values
---- | --- | ---
-AllowSubject | `false` | Boolean
-
-### References
-
-* [https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup](https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup)
-
 ## RSpec/NotToNot
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged