Add RSpec/NoStringifiedNoStringifiedInstanceDoubleConstant

Addresses #1136

.rubocop.yml

@@ -101,34 +101,40 @@ RSpec:
       - expect_no_offenses
       - expect_offense
 
+RSpec/DescribeClass:
+  Exclude:
+    - spec/project/**/*.rb
+
 RSpec/ExampleLength:
   CountAsOne:
     - heredoc
   Max: 11
 
-RSpec/DescribeClass:
-  Exclude:
-    - spec/project/**/*.rb
+RSpec/ExpectInLet:
+  Enabled: true
 
 RSpec/MultipleExpectations:
   Max: 2
 
-# `expect_offense` does not use Kernel#format or String#%
-Style/FormatStringToken:
-  Exclude:
-    - spec/rubocop/**/*.rb
-
-Style/RequireOrder:
+RSpec/NoStringifiedInstanceDoubleConstant:
   Enabled: true
 
 RSpec/SpecFilePathFormat:
   Exclude:
     - spec/rubocop/cop/rspec/mixin/**/*.rb
 
+# `expect_offense` does not use Kernel#format or String#%
+Style/FormatStringToken:
+  Exclude:
+    - spec/rubocop/**/*.rb
+
 Style/NumberedParameters:
   Enabled: true
   EnforcedStyle: disallow
 
+Style/RequireOrder:
+  Enabled: true
+
 # Enable RuboCop's pending cops up to v1.63
 
 Gemspec/DeprecatedAttributeAssignment: {Enabled: true}

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Master (Unreleased)
 
+## 3.0.6 (2024-09-17)
+
+- Add `RSpec/NoStringifiedInstanceDoubleConstant` to check for and correct strings used as instance_doubles. ([@corsonknowles])
+
 ## 3.0.5 (2024-09-07)
 
 - Fix false-negative and error for `RSpec/MetadataStyle` when non-literal args are used in metadata in `EnforceStyle: hash`. ([@cbliard])
@@ -920,6 +924,7 @@ Compatibility release so users can upgrade RuboCop to 0.51.0. No new features.
 [@cfabianski]: https://github.com/cfabianski
 [@clupprich]: https://github.com/clupprich
 [@composerinteralia]: https://github.com/composerinteralia
+[@corsonknowles]: https://github.com/corsonknowles
 [@corydiamand]: https://github.com/corydiamand
 [@darhazer]: https://github.com/Darhazer
 [@daveworth]: https://github.com/daveworth

Rakefile

@@ -76,7 +76,7 @@ task confirm_documentation: :generate_cops_documentation do
     Open3.popen3('git diff --exit-code docs/')
 
   unless process.value.success?
-    raise 'Please run `rake generate_cops_documentation` ' \
+    raise 'Please run `bundle exec rake generate_cops_documentation` ' \
           'and add docs/ to the commit.'
   end
 end

config/default.yml

@@ -726,6 +726,13 @@ RSpec/NoExpectationExample:
     - "^expect_"
     - "^assert_"
 
+RSpec/NoStringifiedInstanceDoubleConstant:
+  Description: Do not use a string as `instance_double` constant.
+  Enabled: pending
+  Safe: false
+  VersionAdded: "<<next>>"
+  Reference: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NoStringifiedInstanceDoubleConstant
+
 RSpec/NotToNot:
   Description: Checks for consistent method usage for negating expectations.
   Enabled: true

docs/modules/ROOT/pages/cops.adoc

@@ -74,6 +74,7 @@
 * xref:cops_rspec.adoc#rspecnamedsubject[RSpec/NamedSubject]
 * xref:cops_rspec.adoc#rspecnestedgroups[RSpec/NestedGroups]
 * xref:cops_rspec.adoc#rspecnoexpectationexample[RSpec/NoExpectationExample]
+* xref:cops_rspec.adoc#rspecnostringifiedinstancedoubleconstant[RSpec/NoStringifiedInstanceDoubleConstant]
 * xref:cops_rspec.adoc#rspecnottonot[RSpec/NotToNot]
 * xref:cops_rspec.adoc#rspecoverwritingsetup[RSpec/OverwritingSetup]
 * xref:cops_rspec.adoc#rspecpending[RSpec/Pending]

docs/modules/ROOT/pages/cops_rspec.adoc

@@ -4117,6 +4117,35 @@ end
 
 * https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NoExpectationExample
 
+== RSpec/NoStringifiedInstanceDoubleConstant
+
+|===
+| Enabled by default | Safe | Supports autocorrection | Version Added | Version Changed
+
+| Pending
+| Yes
+| Always
+| <<next>>
+| -
+|===
+
+Do not use a string as `instance_double` constant.
+
+=== Examples
+
+[source,ruby]
+----
+# bad
+instance_double('Foo', failure_message, stubs)
+
+# good
+instance_double(Foo, failure_message, stubs)
+----
+
+=== References
+
+* https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NoStringifiedInstanceDoubleConstant
+
 == RSpec/NotToNot
 
 |===

lib/rubocop/cop/rspec/no_stringified_instance_double_constant.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      # Do not use a string as `instance_double` constant.
+      #
+      # @example
+      #   # bad
+      #   instance_double('Foo', failure_message, stubs)
+      #
+      #   # good
+      #   instance_double(Foo, failure_message, stubs)
+      #
+      class NoStringifiedInstanceDoubleConstant < Base
+        extend AutoCorrector
+
+        MSG = 'Do not use a string as `instance_double` constant.'
+        RESTRICT_ON_SEND = %i[instance_double].freeze
+
+        # @!method stringified_instance_double_const?(node)
+        def_node_matcher :stringified_instance_double_const?, <<~PATTERN
+          (send nil? :instance_double $...)
+        PATTERN
+
+        def on_send(node)
+          stringified_instance_double_const?(node) do |args_node|
+            if args_node.first.str_type?
+              add_offense(args_node.first) do |corrector|
+                autocorrect(corrector, args_node.first)
+              end
+            end
+          end
+        end
+
+        def autocorrect(corrector, node)
+          corrector.replace(node, node.value)
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rspec_cops.rb

@@ -72,6 +72,7 @@
 require_relative 'rspec/named_subject'
 require_relative 'rspec/nested_groups'
 require_relative 'rspec/no_expectation_example'
+require_relative 'rspec/no_stringified_instance_double_constant'
 require_relative 'rspec/not_to_not'
 require_relative 'rspec/overwriting_setup'
 require_relative 'rspec/pending'

spec/rubocop/cop/rspec/no_stringified_instance_double_constant_spec.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::RSpec::NoStringifiedInstanceDoubleConstant,
+               :config do
+  context 'when using a class for instance_double' do
+    let(:source) do
+      <<~RUBY
+        instance_double(Foo, failure_message, stubs)
+      RUBY
+    end
+
+    it { expect_no_offenses source }
+  end
+
+  context 'when using a symbol for instance_double' do
+    let(:source) do
+      <<~RUBY
+        instance_double(:Foo, failure_message, stubs)
+      RUBY
+    end
+
+    it { expect_no_offenses source }
+  end
+
+  context 'when using a string for instance_double' do
+    it 'replaces the string with the class' do
+      expect_offense <<~RUBY
+        instance_double('Foo', failure_message, stubs)
+                        ^^^^^ Do not use a string as `instance_double` constant.
+      RUBY
+
+      expect_correction <<~RUBY
+        instance_double(Foo, failure_message, stubs)
+      RUBY
+    end
+  end
+end