diff --git a/.rubocop.yml b/.rubocop.yml
index 9e4cc8bd49..44b9d7e874 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -80,3 +80,6 @@ RSpec/MultipleMemoizedHelpers:
 
 RSpec/ContextWording:
   Enabled: false
+
+RSpec/MessageSpies:
+  EnforcedStyle: receive
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index a3956b5bce..f4482aff41 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2024-06-15 15:12:21 UTC using RuboCop version 1.64.1.
+# on 2024-06-22 17:26:10 UTC using RuboCop version 1.64.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -14,13 +14,6 @@ Gemspec/RequireMFA:
   Exclude:
     - 'grape.gemspec'
 
-# Offense count: 1
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowedMethods, AllowedPatterns.
-Lint/AmbiguousBlockAssociation:
-  Exclude:
-    - 'spec/grape/dsl/routing_spec.rb'
-
 # Offense count: 1
 # Configuration parameters: AllowedMethods.
 # AllowedMethods: enums
@@ -28,43 +21,12 @@ Lint/ConstantDefinitionInBlock:
   Exclude:
     - 'spec/grape/validations/validators/except_values_spec.rb'
 
-# Offense count: 3
-# Configuration parameters: IgnoreLiteralBranches, IgnoreConstantBranches.
-Lint/DuplicateBranch:
-  Exclude:
-    - 'spec/support/versioned_helpers.rb'
-
-# Offense count: 1
-# Configuration parameters: AllowComments.
-Lint/EmptyClass:
-  Exclude:
-    - 'lib/grape/dsl/parameters.rb'
-
 # Offense count: 1
 # Configuration parameters: CountComments, Max, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
   Exclude:
     - 'lib/grape/endpoint.rb'
 
-# Offense count: 2
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: EnforcedStyleForLeadingUnderscores.
-# SupportedStylesForLeadingUnderscores: disallowed, required, optional
-Naming/MemoizedInstanceVariableName:
-  Exclude:
-    - 'lib/grape/api/instance.rb'
-    - 'lib/grape/middleware/base.rb'
-
-# Offense count: 5
-# Configuration parameters: MinNameLength, AllowNamesEndingInNumbers, AllowedNames, ForbiddenNames.
-# AllowedNames: as, at, by, cc, db, id, if, in, io, ip, of, on, os, pp, to
-Naming/MethodParameterName:
-  Exclude:
-    - 'lib/grape/endpoint.rb'
-    - 'lib/grape/middleware/error.rb'
-    - 'lib/grape/middleware/stack.rb'
-    - 'spec/grape/api_spec.rb'
-
 # Offense count: 18
 # Configuration parameters: EnforcedStyle, CheckMethodNames, CheckSymbols, AllowedIdentifiers, AllowedPatterns.
 # SupportedStyles: snake_case, normalcase, non_integer
@@ -117,10 +79,9 @@ RSpec/ExpectActual:
     - 'spec/grape/endpoint/declared_spec.rb'
     - 'spec/grape/middleware/exception_spec.rb'
 
-# Offense count: 3
+# Offense count: 1
 RSpec/ExpectInHook:
   Exclude:
-    - 'spec/grape/api_spec.rb'
     - 'spec/grape/validations/validators/values_spec.rb'
 
 # Offense count: 6
@@ -147,31 +108,16 @@ RSpec/LeakyConstantDeclaration:
   Exclude:
     - 'spec/grape/validations/validators/except_values_spec.rb'
 
-# Offense count: 2
+# Offense count: 1
 RSpec/MessageChain:
   Exclude:
     - 'spec/grape/middleware/formatter_spec.rb'
 
-# Offense count: 144
-# Configuration parameters: .
-# SupportedStyles: have_received, receive
-RSpec/MessageSpies:
-  EnforcedStyle: receive
-
 # Offense count: 12
 RSpec/MissingExampleGroupArgument:
   Exclude:
     - 'spec/grape/middleware/exception_spec.rb'
 
-# Offense count: 17
-# Configuration parameters: AllowedPatterns.
-# AllowedPatterns: ^expect_, ^assert_
-RSpec/NoExpectationExample:
-  Exclude:
-    - 'spec/grape/api_remount_spec.rb'
-    - 'spec/grape/api_spec.rb'
-    - 'spec/grape/validations_spec.rb'
-
 # Offense count: 12
 RSpec/RepeatedDescription:
   Exclude:
@@ -180,10 +126,9 @@ RSpec/RepeatedDescription:
     - 'spec/grape/validations/validators/allow_blank_spec.rb'
     - 'spec/grape/validations/validators/values_spec.rb'
 
-# Offense count: 8
+# Offense count: 6
 RSpec/RepeatedExample:
   Exclude:
-    - 'spec/grape/api_spec.rb'
     - 'spec/grape/middleware/versioner/accept_version_header_spec.rb'
     - 'spec/grape/validations/validators/allow_blank_spec.rb'
 
@@ -195,13 +140,6 @@ RSpec/RepeatedExampleGroupDescription:
     - 'spec/grape/util/inheritable_setting_spec.rb'
     - 'spec/grape/validations/validators/values_spec.rb'
 
-# Offense count: 2
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AutoCorrect.
-RSpec/ScatteredSetup:
-  Exclude:
-    - 'spec/grape/util/inheritable_setting_spec.rb'
-
 # Offense count: 5
 RSpec/StubbedMock:
   Exclude:
@@ -228,7 +166,7 @@ RSpec/SubjectStub:
     - 'spec/grape/middleware/stack_spec.rb'
     - 'spec/grape/parser_spec.rb'
 
-# Offense count: 24
+# Offense count: 23
 # Configuration parameters: IgnoreNameless, IgnoreSymbolicNames.
 RSpec/VerifiedDoubles:
   Exclude:
@@ -251,13 +189,6 @@ Style/CombinableLoops:
   Exclude:
     - 'spec/grape/endpoint_spec.rb'
 
-# Offense count: 2
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: MaxUnannotatedPlaceholdersAllowed, AllowedMethods, AllowedPatterns.
-# SupportedStyles: annotated, template, unannotated
-Style/FormatStringToken:
-  EnforcedStyle: template
-
 # Offense count: 12
 # Configuration parameters: AllowedMethods.
 # AllowedMethods: respond_to_missing?
@@ -274,55 +205,3 @@ Style/OptionalBooleanParameter:
     - 'lib/grape/validations/types/dry_type_coercer.rb'
     - 'lib/grape/validations/types/primitive_coercer.rb'
     - 'lib/grape/validations/types/set_coercer.rb'
-
-# Offense count: 29
-# This cop supports safe autocorrection (--autocorrect).
-Style/RedundantConstantBase:
-  Exclude:
-    - 'spec/grape/api/invalid_format_spec.rb'
-    - 'spec/grape/api_spec.rb'
-    - 'spec/grape/dsl/logger_spec.rb'
-    - 'spec/grape/endpoint/declared_spec.rb'
-    - 'spec/grape/endpoint_spec.rb'
-    - 'spec/grape/middleware/formatter_spec.rb'
-    - 'spec/grape/validations/validators/coerce_spec.rb'
-    - 'spec/grape/validations/validators/default_spec.rb'
-    - 'spec/integration/multi_json/json_spec.rb'
-    - 'spec/integration/multi_xml/xml_spec.rb'
-
-# Offense count: 2
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowAsExpressionSeparator.
-Style/Semicolon:
-  Exclude:
-    - 'spec/grape/api_spec.rb'
-
-# Offense count: 2
-# This cop supports safe autocorrection (--autocorrect).
-Style/SuperArguments:
-  Exclude:
-    - 'lib/grape/api.rb'
-    - 'spec/support/deprecated_warning_handlers.rb'
-
-# Offense count: 2
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: AllowMethodsWithArguments, AllowedMethods, AllowedPatterns, AllowComments.
-# AllowedMethods: define_method
-Style/SymbolProc:
-  Exclude:
-    - 'benchmark/large_model.rb'
-    - 'spec/grape/validations/params_scope_spec.rb'
-
-# Offense count: 1
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: forbid_for_all_comparison_operators, forbid_for_equality_operators_only, require_for_all_comparison_operators, require_for_equality_operators_only
-Style/YodaCondition:
-  Exclude:
-    - 'lib/grape/api.rb'
-
-# Offense count: 1
-# This cop supports unsafe autocorrection (--autocorrect-all).
-Style/ZeroLengthPredicate:
-  Exclude:
-    - 'lib/grape/validations/validators/exactly_one_of_validator.rb'
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4dec503c80..f384013f84 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 #### Fixes
 
+* [#2459](https://github.com/ruby-grape/grape/pull/2459): Autocorrect cops - [@ericproulx](https://github.com/ericproulx).
 * [#3458](https://github.com/ruby-grape/grape/pull/2458): Remove unused Grape::Util::Accept::Header - [@ericproulx](https://github.com/ericproulx).
 * Your contribution here.
 
diff --git a/benchmark/large_model.rb b/benchmark/large_model.rb
index 27dc9a3574..9eaa1a5288 100644
--- a/benchmark/large_model.rb
+++ b/benchmark/large_model.rb
@@ -140,7 +140,7 @@ def self.vrp_request_configuration(this)
   def self.vrp_request_partition(this)
     this.requires(:method, type: String, values: %w[hierarchical_tree balanced_kmeans])
     this.optional(:metric, type: Symbol)
-    this.optional(:entity, type: Symbol, values: %i[vehicle work_day], coerce_with: ->(value) { value.to_sym })
+    this.optional(:entity, type: Symbol, values: %i[vehicle work_day], coerce_with: lambda(&:to_sym))
     this.optional(:threshold, type: Integer)
   end
 
diff --git a/lib/grape/api.rb b/lib/grape/api.rb
index 38f17dcc56..eaa351c9bf 100644
--- a/lib/grape/api.rb
+++ b/lib/grape/api.rb
@@ -32,7 +32,7 @@ def new(...)
       def inherited(api)
         super
 
-        api.initial_setup(Grape::API == self ? Grape::API::Instance : @base_instance)
+        api.initial_setup(self == Grape::API ? Grape::API::Instance : @base_instance)
         api.override_all_methods!
       end
 
@@ -108,7 +108,7 @@ def replay_setup_on(instance)
       end
 
       def respond_to?(method, include_private = false)
-        super(method, include_private) || base_instance.respond_to?(method, include_private)
+        super || base_instance.respond_to?(method, include_private)
       end
 
       def respond_to_missing?(method, include_private = false)
diff --git a/lib/grape/api/instance.rb b/lib/grape/api/instance.rb
index a17c8e63f0..ce290df7cc 100644
--- a/lib/grape/api/instance.rb
+++ b/lib/grape/api/instance.rb
@@ -46,7 +46,7 @@ def reset!
         # Parses the API's definition and compiles it into an instance of
         # Grape::API.
         def compile
-          @instance ||= new
+          @instance ||= new # rubocop:disable Naming/MemoizedInstanceVariableName
         end
 
         # Wipe the compiled API so we can recompile after changes were made.
diff --git a/lib/grape/dsl/parameters.rb b/lib/grape/dsl/parameters.rb
index bfc9b408e3..821da5d793 100644
--- a/lib/grape/dsl/parameters.rb
+++ b/lib/grape/dsl/parameters.rb
@@ -231,7 +231,7 @@ def declared_param?(param)
 
       alias group requires
 
-      class EmptyOptionalValue; end
+      class EmptyOptionalValue; end # rubocop:disable Lint/EmptyClass
 
       def map_params(params, element, is_array = false)
         if params.is_a?(Array)
diff --git a/lib/grape/endpoint.rb b/lib/grape/endpoint.rb
index 7fc83fc437..cc1fdba833 100644
--- a/lib/grape/endpoint.rb
+++ b/lib/grape/endpoint.rb
@@ -231,8 +231,8 @@ def endpoints
       options[:app].endpoints if options[:app].respond_to?(:endpoints)
     end
 
-    def equals?(e)
-      (options == e.options) && (inheritable_setting.to_hash == e.inheritable_setting.to_hash)
+    def equals?(endpoint)
+      (options == endpoint.options) && (inheritable_setting.to_hash == endpoint.inheritable_setting.to_hash)
     end
 
     protected
diff --git a/lib/grape/exceptions/validation_errors.rb b/lib/grape/exceptions/validation_errors.rb
index 09e4a37b0a..b8a843b1a5 100644
--- a/lib/grape/exceptions/validation_errors.rb
+++ b/lib/grape/exceptions/validation_errors.rb
@@ -4,7 +4,7 @@ module Grape
   module Exceptions
     class ValidationErrors < Grape::Exceptions::Base
       ERRORS_FORMAT_KEY = 'grape.errors.format'
-      DEFAULT_ERRORS_FORMAT = '%{attributes} %{message}'
+      DEFAULT_ERRORS_FORMAT = '%<attributes>s %<message>s'
 
       include Enumerable
 
diff --git a/lib/grape/middleware/base.rb b/lib/grape/middleware/base.rb
index 87f2429fff..2ee9cbeaea 100644
--- a/lib/grape/middleware/base.rb
+++ b/lib/grape/middleware/base.rb
@@ -74,7 +74,7 @@ def content_type
       end
 
       def mime_types
-        @mime_type ||= content_types.each_pair.with_object({}) do |(k, v), types_without_params|
+        @mime_types ||= content_types.each_pair.with_object({}) do |(k, v), types_without_params|
           types_without_params[v.split(';').first] = k
         end
       end
diff --git a/lib/grape/middleware/error.rb b/lib/grape/middleware/error.rb
index b1fc02767f..2dc71c1daf 100644
--- a/lib/grape/middleware/error.rb
+++ b/lib/grape/middleware/error.rb
@@ -74,8 +74,8 @@ def error_response(error = {})
         rack_response(status, headers, format_message(message, backtrace, original_exception))
       end
 
-      def default_rescue_handler(e)
-        error_response(message: e.message, backtrace: e.backtrace, original_exception: e)
+      def default_rescue_handler(exception)
+        error_response(message: exception.message, backtrace: exception.backtrace, original_exception: exception)
       end
 
       def rescue_handler_for_base_only_class(klass)
diff --git a/lib/grape/middleware/stack.rb b/lib/grape/middleware/stack.rb
index 9ba339a78e..8e25af385f 100644
--- a/lib/grape/middleware/stack.rb
+++ b/lib/grape/middleware/stack.rb
@@ -57,8 +57,8 @@ def last
         middlewares.last
       end
 
-      def [](i)
-        middlewares[i]
+      def [](index)
+        middlewares[index]
       end
 
       def insert(index, *args, &block)
diff --git a/lib/grape/validations/validators/exactly_one_of_validator.rb b/lib/grape/validations/validators/exactly_one_of_validator.rb
index 735c457019..aa1c54711c 100644
--- a/lib/grape/validations/validators/exactly_one_of_validator.rb
+++ b/lib/grape/validations/validators/exactly_one_of_validator.rb
@@ -7,7 +7,7 @@ class ExactlyOneOfValidator < MultipleParamsBase
         def validate_params!(params)
           keys = keys_in_common(params)
           return if keys.length == 1
-          raise Grape::Exceptions::Validation.new(params: all_keys, message: message(:exactly_one)) if keys.length.zero?
+          raise Grape::Exceptions::Validation.new(params: all_keys, message: message(:exactly_one)) if keys.empty?
 
           raise Grape::Exceptions::Validation.new(params: keys, message: message(:mutual_exclusion))
         end
diff --git a/spec/grape/api/invalid_format_spec.rb b/spec/grape/api/invalid_format_spec.rb
index 79da1ac1db..0e6399d32c 100644
--- a/spec/grape/api/invalid_format_spec.rb
+++ b/spec/grape/api/invalid_format_spec.rb
@@ -27,19 +27,19 @@ def app
     it 'no format' do
       get '/foo'
       expect(last_response.status).to eq 200
-      expect(last_response.body).to eq(::Grape::Json.dump(id: 'foo', format: nil))
+      expect(last_response.body).to eq(Grape::Json.dump(id: 'foo', format: nil))
     end
 
     it 'json format' do
       get '/foo.json'
       expect(last_response.status).to eq 200
-      expect(last_response.body).to eq(::Grape::Json.dump(id: 'foo', format: 'json'))
+      expect(last_response.body).to eq(Grape::Json.dump(id: 'foo', format: 'json'))
     end
 
     it 'invalid format' do
       get '/foo.invalid'
       expect(last_response.status).to eq 200
-      expect(last_response.body).to eq(::Grape::Json.dump(id: 'foo', format: 'invalid'))
+      expect(last_response.body).to eq(Grape::Json.dump(id: 'foo', format: 'invalid'))
     end
   end
 end
diff --git a/spec/grape/api_remount_spec.rb b/spec/grape/api_remount_spec.rb
index 2c6c6ae4bb..793d49d9fd 100644
--- a/spec/grape/api_remount_spec.rb
+++ b/spec/grape/api_remount_spec.rb
@@ -306,13 +306,15 @@
               tags ['not_configurable_tag', configuration[:a_configurable_tag]]
             end
             get 'location' do
-              'success'
+              route.tags
             end
           end
         end
 
         it 'mounts the endpoint with the appropiate tags' do
           root_api.mount({ a_remounted_api => 'integer' }, with: { a_configurable_tag: 'a configured tag' })
+          get '/integer/location', param_key: 'a'
+          expect(JSON.parse(last_response.body)).to eq ['not_configurable_tag', 'a configured tag']
         end
       end
 
diff --git a/spec/grape/api_spec.rb b/spec/grape/api_spec.rb
index fbd0ee38c7..dd280c9a56 100644
--- a/spec/grape/api_spec.rb
+++ b/spec/grape/api_spec.rb
@@ -287,8 +287,10 @@ def subject.enable_root_route!
         end
       end
 
-      after do
-        expect(last_response.body).to eql 'root'
+      shared_examples_for 'a root route' do
+        it 'returns root' do
+          expect(last_response.body).to eql 'root'
+        end
       end
 
       describe 'path versioned APIs' do
@@ -300,56 +302,104 @@ def subject.enable_root_route!
         context 'when a single version provided' do
           let(:version) { 'v1' }
 
-          it 'without a format' do
-            versioned_get '/', 'v1', using: :path
+          context 'without a format' do
+            before do
+              versioned_get '/', 'v1', using: :path
+            end
+
+            it_behaves_like 'a root route'
           end
 
-          it 'with a format' do
-            get '/v1/.json'
+          context 'with a format' do
+            before do
+              get '/v1/.json'
+            end
+
+            it_behaves_like 'a root route'
           end
         end
 
         context 'when array of versions provided' do
           let(:version) { %w[v1 v2] }
 
-          it { versioned_get '/', 'v1', using: :path }
-          it { versioned_get '/', 'v2', using: :path }
+          context 'when v1' do
+            before do
+              versioned_get '/', 'v1', using: :path
+            end
+
+            it_behaves_like 'a root route'
+          end
+
+          context 'when v2' do
+            before do
+              versioned_get '/', 'v2', using: :path
+            end
+
+            it_behaves_like 'a root route'
+          end
         end
       end
 
-      it 'header versioned APIs' do
-        subject.version 'v1', using: :header, vendor: 'test'
-        subject.enable_root_route!
+      context 'when header versioned APIs' do
+        before do
+          subject.version 'v1', using: :header, vendor: 'test'
+          subject.enable_root_route!
+          versioned_get '/', 'v1', using: :header, vendor: 'test'
+        end
 
-        versioned_get '/', 'v1', using: :header, vendor: 'test'
+        it_behaves_like 'a root route'
       end
 
-      it 'header versioned APIs with multiple headers' do
-        subject.version %w[v1 v2], using: :header, vendor: 'test'
-        subject.enable_root_route!
+      context 'when header versioned APIs with multiple headers' do
+        before do
+          subject.version %w[v1 v2], using: :header, vendor: 'test'
+          subject.enable_root_route!
+        end
+
+        context 'when v1' do
+          before do
+            versioned_get '/', 'v1', using: :header, vendor: 'test'
+          end
 
-        versioned_get '/', 'v1', using: :header, vendor: 'test'
-        versioned_get '/', 'v2', using: :header, vendor: 'test'
+          it_behaves_like 'a root route'
+        end
+
+        context 'when v2' do
+          before do
+            versioned_get '/', 'v2', using: :header, vendor: 'test'
+          end
+
+          it_behaves_like 'a root route'
+        end
       end
 
-      it 'param versioned APIs' do
-        subject.version 'v1', using: :param
-        subject.enable_root_route!
+      context 'param versioned APIs' do
+        before do
+          subject.version 'v1', using: :param
+          subject.enable_root_route!
+          versioned_get '/', 'v1', using: :param
+        end
 
-        versioned_get '/', 'v1', using: :param
+        it_behaves_like 'a root route'
       end
 
-      it 'Accept-Version header versioned APIs' do
-        subject.version 'v1', using: :accept_version_header
-        subject.enable_root_route!
+      context 'when Accept-Version header versioned APIs' do
+        before do
+          subject.version 'v1', using: :accept_version_header
+          subject.enable_root_route!
+          versioned_get '/', 'v1', using: :accept_version_header
+        end
 
-        versioned_get '/', 'v1', using: :accept_version_header
+        it_behaves_like 'a root route'
       end
 
-      it 'unversioned APIs' do
-        subject.enable_root_route!
+      context 'unversioned APIss' do
+        before do
+          subject.enable_root_route!
+          get '/'
+        end
 
-        get '/'
+        it_behaves_like 'a root route'
       end
     end
 
@@ -438,9 +488,9 @@ def to_txt
             subject.send(verb) do
               env[Grape::Env::API_REQUEST_BODY]
             end
-            send verb, '/', ::Grape::Json.dump(object), 'CONTENT_TYPE' => 'application/json'
+            send verb, '/', Grape::Json.dump(object), 'CONTENT_TYPE' => 'application/json'
             expect(last_response.status).to eq(verb == :post ? 201 : 200)
-            expect(last_response.body).to eql ::Grape::Json.dump(object)
+            expect(last_response.body).to eql Grape::Json.dump(object)
             expect(last_request.params).to eql({})
           end
 
@@ -449,9 +499,9 @@ def to_txt
             subject.send(verb) do
               env[Grape::Env::API_REQUEST_INPUT]
             end
-            send verb, '/', ::Grape::Json.dump(object), 'CONTENT_TYPE' => 'application/json'
+            send verb, '/', Grape::Json.dump(object), 'CONTENT_TYPE' => 'application/json'
             expect(last_response.status).to eq(verb == :post ? 201 : 200)
-            expect(last_response.body).to eql ::Grape::Json.dump(object).to_json
+            expect(last_response.body).to eql Grape::Json.dump(object).to_json
           end
 
           context 'chunked transfer encoding' do
@@ -460,9 +510,9 @@ def to_txt
               subject.send(verb) do
                 env[Grape::Env::API_REQUEST_INPUT]
               end
-              send verb, '/', ::Grape::Json.dump(object), 'CONTENT_TYPE' => 'application/json', Grape::Http::Headers::HTTP_TRANSFER_ENCODING => 'chunked'
+              send verb, '/', Grape::Json.dump(object), 'CONTENT_TYPE' => 'application/json', Grape::Http::Headers::HTTP_TRANSFER_ENCODING => 'chunked'
               expect(last_response.status).to eq(verb == :post ? 201 : 200)
-              expect(last_response.body).to eql ::Grape::Json.dump(object).to_json
+              expect(last_response.body).to eql Grape::Json.dump(object).to_json
             end
           end
         end
@@ -993,9 +1043,14 @@ def to_txt
   end
 
   describe '.compile!' do
-    it 'compiles the instance for rack!' do
-      stubbed_object = double(:instance_for_rack)
-      allow(app).to receive(:instance_for_rack) { stubbed_object }
+    let(:base_instance) { app.base_instance }
+
+    before do
+      allow(base_instance).to receive(:compile!).and_return(:compiled!)
+    end
+
+    it 'returns compiled!' do
+      expect(app.send(:compile!)).to eq(:compiled!)
     end
   end
 
@@ -1593,8 +1648,8 @@ def call(env)
 
     it 'has access to helper methods' do
       subject.helpers do
-        def authorize(u, p)
-          u == 'allow' && p == 'whatever'
+        def authorize(user, password)
+          user == 'allow' && password == 'whatever'
         end
       end
 
@@ -1634,7 +1689,7 @@ def authorize(u, p)
           def self.io
             @io ||= StringIO.new
           end
-          logger ::Logger.new(io)
+          logger Logger.new(io)
         end
       end
 
@@ -2496,7 +2551,7 @@ def self.call(message, _backtrace, _options, _env, _original_exception)
         raise 'rain!'
       end
       get '/exception'
-      json = ::Grape::Json.load(last_response.body)
+      json = Grape::Json.load(last_response.body)
       expect(json['error']).to eql 'rain!'
       expect(json['backtrace'].length).to be > 0
     end
@@ -2511,24 +2566,26 @@ def self.call(message, _backtrace, _options, _env, _original_exception)
     end
 
     context 'with json format' do
-      before { subject.format :json }
+      shared_examples_for 'a json format api' do |error_message|
+        subject { JSON.parse(last_response.body) }
 
-      after do
-        get '/error'
-        expect(last_response.body).to eql('{"error":"failure"}')
-      end
+        before  { get '/error' }
 
-      it 'rescues error! called with a string and returns json' do
-        subject.get('/error') { error!(:failure, 401) }
-      end
+        let(:app) do
+          Class.new(Grape::API) do
+            format :json
+            get('/error') { error!(error_message, 401) }
+          end
+        end
 
-      it 'rescues error! called with a symbol and returns json' do
-        subject.get('/error') { error!(:failure, 401) }
+        context "when error! called with #{error_message.class.name}" do
+          it { is_expected.to eq('error' => 'failure') }
+        end
       end
 
-      it 'rescues error! called with a hash and returns json' do
-        subject.get('/error') { error!({ error: :failure }, 401) }
-      end
+      it_behaves_like 'a json format api', 'failure'
+      it_behaves_like 'a json format api', :failure
+      it_behaves_like 'a json format api', { error: :failure }
     end
   end
 
@@ -3083,13 +3140,13 @@ def self.call(object, _env)
         optional :param2
       end
       subject.namespace 'ns1' do
-        get { ; }
+        get {}
       end
       subject.params do
         optional :param2
       end
       subject.namespace 'ns2' do
-        get { ; }
+        get {}
       end
       routes_doc = subject.routes.map do |route|
         { description: route.description, params: route.params }
@@ -3216,6 +3273,12 @@ def self.call(object, _env)
           optional :bar
         end
       end
+      subject.get 'method'
+      expect(subject.routes.map do |route|
+        { description: route.description, params: route.params }
+      end).to eq [
+        { description: nil, params: { 'foo' => { required: true, type: 'Array' }, 'foo[bar]' => { required: false } } }
+      ]
     end
 
     it 'parses parameters when no description is given' do
@@ -3693,7 +3756,7 @@ def my_method
 
     it 'path' do
       get '/endpoint/options'
-      options = ::Grape::Json.load(last_response.body)
+      options = Grape::Json.load(last_response.body)
       expect(options['path']).to eq(['/endpoint/options'])
       expect(options['source_location'][0]).to include 'api_spec.rb'
       expect(options['source_location'][1].to_i).to be > 0
diff --git a/spec/grape/dsl/logger_spec.rb b/spec/grape/dsl/logger_spec.rb
index 2c9739f75e..ae1bab5671 100644
--- a/spec/grape/dsl/logger_spec.rb
+++ b/spec/grape/dsl/logger_spec.rb
@@ -9,7 +9,7 @@
     end
   end
 
-  let(:logger) { instance_double(::Logger) }
+  let(:logger) { instance_double(Logger) }
 
   describe '.logger' do
     it 'sets a logger' do
diff --git a/spec/grape/dsl/routing_spec.rb b/spec/grape/dsl/routing_spec.rb
index 6d64586198..e763428f61 100644
--- a/spec/grape/dsl/routing_spec.rb
+++ b/spec/grape/dsl/routing_spec.rb
@@ -259,7 +259,7 @@ class Dummy
         it 'does not modify options parameter' do
           allow(subject).to receive(:namespace)
           expect { subject.route_param('foo', options, &proc {}) }
-            .not_to change { options }
+            .not_to(change { options })
         end
       end
 
diff --git a/spec/grape/endpoint/declared_spec.rb b/spec/grape/endpoint/declared_spec.rb
index dcf2fe9d62..6bf5d206ca 100644
--- a/spec/grape/endpoint/declared_spec.rb
+++ b/spec/grape/endpoint/declared_spec.rb
@@ -281,7 +281,7 @@
         ''
       end
 
-      post '/declared', ::Grape::Json.dump(first: 'one', boolean: false), 'CONTENT_TYPE' => 'application/json'
+      post '/declared', Grape::Json.dump(first: 'one', boolean: false), 'CONTENT_TYPE' => 'application/json'
       expect(last_response).to be_created
     end
 
@@ -296,7 +296,7 @@
         ''
       end
 
-      post '/declared', ::Grape::Json.dump(first: 'one', second: nil), 'CONTENT_TYPE' => 'application/json'
+      post '/declared', Grape::Json.dump(first: 'one', second: nil), 'CONTENT_TYPE' => 'application/json'
       expect(last_response).to be_created
     end
 
diff --git a/spec/grape/endpoint_spec.rb b/spec/grape/endpoint_spec.rb
index ee4c8986d5..ee44efc39a 100644
--- a/spec/grape/endpoint_spec.rb
+++ b/spec/grape/endpoint_spec.rb
@@ -371,7 +371,7 @@ def app
       end
 
       it 'converts JSON bodies to params' do
-        post '/request_body', ::Grape::Json.dump(user: 'Bobby T.'), 'CONTENT_TYPE' => 'application/json'
+        post '/request_body', Grape::Json.dump(user: 'Bobby T.'), 'CONTENT_TYPE' => 'application/json'
         expect(last_response.body).to eq('Bobby T.')
       end
 
@@ -407,7 +407,7 @@ def app
           error! 400, 'expected nil' if params[:version]
           params[:user]
         end
-        post '/omitted_params', ::Grape::Json.dump(user: 'Bob'), 'CONTENT_TYPE' => 'application/json'
+        post '/omitted_params', Grape::Json.dump(user: 'Bob'), 'CONTENT_TYPE' => 'application/json'
         expect(last_response.status).to eq(201)
         expect(last_response.body).to eq('Bob')
       end
@@ -464,7 +464,7 @@ def app
       subject.put '/request_body' do
         params[:user]
       end
-      put '/request_body', ::Grape::Json.dump(user: 'Bob'), 'CONTENT_TYPE' => 'text/plain'
+      put '/request_body', Grape::Json.dump(user: 'Bob'), 'CONTENT_TYPE' => 'text/plain'
 
       expect(last_response.status).to eq(415)
       expect(last_response.body).to eq('{"error":"The provided content-type \'text/plain\' is not supported."}')
@@ -478,7 +478,7 @@ def app
         subject.post do
           params[:data]
         end
-        post '/', ::Grape::Json.dump(data: { some: 'payload' }), 'CONTENT_TYPE' => 'application/json'
+        post '/', Grape::Json.dump(data: { some: 'payload' }), 'CONTENT_TYPE' => 'application/json'
       end
 
       it 'does not response with 406 for same type without params' do
diff --git a/spec/grape/middleware/formatter_spec.rb b/spec/grape/middleware/formatter_spec.rb
index 61a2a67bf9..9b7dc9b56e 100644
--- a/spec/grape/middleware/formatter_spec.rb
+++ b/spec/grape/middleware/formatter_spec.rb
@@ -16,7 +16,7 @@
 
     it 'looks at the bodies for possibly serializable data' do
       r = Rack::MockResponse[*subject.call(env)]
-      expect(r.body).to eq(::Grape::Json.dump(body))
+      expect(r.body).to eq(Grape::Json.dump(body))
     end
 
     context 'default format' do
@@ -336,7 +336,7 @@ def to_xml
         let(:io) { double }
 
         before do
-          allow(io).to receive_message_chain(:rewind, :read).and_return(nil)
+          allow(io).to receive_message_chain(rewind: nil, read: nil)
         end
 
         it 'does not read and parse the body' do
@@ -355,7 +355,7 @@ def to_xml
         let(:io) { double }
 
         before do
-          allow(io).to receive_message_chain(:rewind, :read).and_return('')
+          allow(io).to receive_messages(rewind: nil, read: '')
         end
 
         it 'does not read and parse the body' do
diff --git a/spec/grape/util/inheritable_setting_spec.rb b/spec/grape/util/inheritable_setting_spec.rb
index 2941b31810..c9ad93bd9e 100644
--- a/spec/grape/util/inheritable_setting_spec.rb
+++ b/spec/grape/util/inheritable_setting_spec.rb
@@ -5,6 +5,7 @@ module Util
     describe InheritableSetting do
       before do
         described_class.reset_global!
+        subject.inherit_from parent
       end
 
       let(:parent) do
@@ -28,10 +29,6 @@ module Util
         end
       end
 
-      before do
-        subject.inherit_from parent
-      end
-
       describe '#global' do
         it 'sets a global value' do
           subject.global[:some_thing] = :foo_bar
diff --git a/spec/grape/validations/params_scope_spec.rb b/spec/grape/validations/params_scope_spec.rb
index af6a4a2c93..454fdf6c03 100644
--- a/spec/grape/validations/params_scope_spec.rb
+++ b/spec/grape/validations/params_scope_spec.rb
@@ -58,7 +58,7 @@ def initialize(value)
 
     it do
       subject.params do
-        requires :foo, as: :bar, type: String, coerce_with: ->(c) { c.strip }
+        requires :foo, as: :bar, type: String, coerce_with: lambda(&:strip)
       end
       subject.get('/renaming-coerced') { "#{params['bar']}-#{params['foo']}" }
       get '/renaming-coerced', foo: ' there we go '
diff --git a/spec/grape/validations/validators/coerce_spec.rb b/spec/grape/validations/validators/coerce_spec.rb
index 6b8f500686..81cd4b5119 100644
--- a/spec/grape/validations/validators/coerce_spec.rb
+++ b/spec/grape/validations/validators/coerce_spec.rb
@@ -655,19 +655,19 @@ def self.parse(_val)
           params[:values]
         end
 
-        post '/coerce_nested_strings', ::Grape::Json.dump(values: 'a,b,c,d'), 'CONTENT_TYPE' => 'application/json'
+        post '/coerce_nested_strings', Grape::Json.dump(values: 'a,b,c,d'), 'CONTENT_TYPE' => 'application/json'
         expect(last_response).to be_created
         expect(JSON.parse(last_response.body)).to eq([%w[a b c d]])
 
-        post '/coerce_nested_strings', ::Grape::Json.dump(values: [%w[a c], %w[b]]), 'CONTENT_TYPE' => 'application/json'
+        post '/coerce_nested_strings', Grape::Json.dump(values: [%w[a c], %w[b]]), 'CONTENT_TYPE' => 'application/json'
         expect(last_response).to be_created
         expect(JSON.parse(last_response.body)).to eq([%w[a c], %w[b]])
 
-        post '/coerce_nested_strings', ::Grape::Json.dump(values: [[]]), 'CONTENT_TYPE' => 'application/json'
+        post '/coerce_nested_strings', Grape::Json.dump(values: [[]]), 'CONTENT_TYPE' => 'application/json'
         expect(last_response).to be_created
         expect(JSON.parse(last_response.body)).to eq([[]])
 
-        post '/coerce_nested_strings', ::Grape::Json.dump(values: [['a', { bar: 0 }], ['b']]), 'CONTENT_TYPE' => 'application/json'
+        post '/coerce_nested_strings', Grape::Json.dump(values: [['a', { bar: 0 }], ['b']]), 'CONTENT_TYPE' => 'application/json'
         expect(last_response).to be_bad_request
       end
 
diff --git a/spec/grape/validations/validators/default_spec.rb b/spec/grape/validations/validators/default_spec.rb
index 2bb59792d8..df84f06ee3 100644
--- a/spec/grape/validations/validators/default_spec.rb
+++ b/spec/grape/validations/validators/default_spec.rb
@@ -382,8 +382,8 @@ def app
         [JSON, { test: 'non-empty-string' }.to_json],
         [Array[JSON], []],
         [Array[JSON], [{ test: 'non-empty-string' }.to_json]],
-        [::File, ''],
-        [::File, { test: 'non-empty-string' }.to_json],
+        [File, ''],
+        [File, { test: 'non-empty-string' }.to_json],
         [Rack::Multipart::UploadedFile, ''],
         [Rack::Multipart::UploadedFile, { test: 'non-empty-string' }.to_json]
       ].each do |type, default|
diff --git a/spec/grape/validations_spec.rb b/spec/grape/validations_spec.rb
index 12acb33d3c..8f7db50c4b 100644
--- a/spec/grape/validations_spec.rb
+++ b/spec/grape/validations_spec.rb
@@ -4,11 +4,7 @@
   subject { Class.new(Grape::API) }
 
   let(:app) { subject }
-  let(:declard_params) {}
-
-  def declared_params
-    subject.namespace_stackable(:declared_params).flatten
-  end
+  let(:declared_params) { subject.namespace_stackable(:declared_params).flatten }
 
   describe 'params' do
     context 'optional' do
@@ -1365,24 +1361,6 @@ def validate_param!(attr_name, params)
     end
 
     context 'named' do
-      context 'can be defined' do
-        it 'in helpers' do
-          subject.helpers do
-            params :pagination do
-            end
-          end
-        end
-
-        it 'in helper module which kind of Grape::DSL::Helpers::BaseHelper' do
-          shared_params = Module.new do
-            extend Grape::DSL::Helpers::BaseHelper
-            params :pagination do
-            end
-          end
-          subject.helpers shared_params
-        end
-      end
-
       context 'can be included in usual params' do
         before do
           shared_params = Module.new do
diff --git a/spec/integration/multi_json/json_spec.rb b/spec/integration/multi_json/json_spec.rb
index 994a0aeb2b..56ded26b02 100644
--- a/spec/integration/multi_json/json_spec.rb
+++ b/spec/integration/multi_json/json_spec.rb
@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
 # grape_entity depends on multi-json and it breaks the test.
-describe Grape::Json, if: defined?(::MultiJson) && !defined?(Grape::Entity) do
+describe Grape::Json, if: defined?(MultiJson) && !defined?(Grape::Entity) do
   subject { described_class }
 
-  it { is_expected.to eq(::MultiJson) }
+  it { is_expected.to eq(MultiJson) }
 end
diff --git a/spec/integration/multi_xml/xml_spec.rb b/spec/integration/multi_xml/xml_spec.rb
index cda102b1d2..a5d998847e 100644
--- a/spec/integration/multi_xml/xml_spec.rb
+++ b/spec/integration/multi_xml/xml_spec.rb
@@ -3,5 +3,5 @@
 describe Grape::Xml, if: defined?(MultiXml) do
   subject { described_class }
 
-  it { is_expected.to eq(::MultiXml) }
+  it { is_expected.to eq(MultiXml) }
 end
diff --git a/spec/support/deprecated_warning_handlers.rb b/spec/support/deprecated_warning_handlers.rb
index 85c4bb78d5..040410fb1d 100644
--- a/spec/support/deprecated_warning_handlers.rb
+++ b/spec/support/deprecated_warning_handlers.rb
@@ -8,7 +8,7 @@ class DeprecationWarning < StandardError; end
   DEPRECATION_REGEX = /is deprecated/.freeze
 
   def warn(message)
-    return super(message) unless message.match?(DEPRECATION_REGEX)
+    return super unless message.match?(DEPRECATION_REGEX)
 
     exception = DeprecationWarning.new(message)
     exception.set_backtrace(caller)
diff --git a/spec/support/versioned_helpers.rb b/spec/support/versioned_helpers.rb
index e216f7c8f6..75e56e7d18 100644
--- a/spec/support/versioned_helpers.rb
+++ b/spec/support/versioned_helpers.rb
@@ -10,11 +10,7 @@ def versioned_path(**options)
         case options[:using]
         when :path
           File.join('/', options[:prefix] || '', options[:version], options[:path])
-        when :param
-          File.join('/', options[:prefix] || '', options[:path])
-        when :header
-          File.join('/', options[:prefix] || '', options[:path])
-        when :accept_version_header
+        when :param, :header, :accept_version_header
           File.join('/', options[:prefix] || '', options[:path])
         else
           raise ArgumentError.new("unknown versioning strategy: #{options[:using]}")
@@ -23,10 +19,8 @@ def versioned_path(**options)
 
       def versioned_headers(**options)
         case options[:using]
-        when :path
-          {}  # no-op
-        when :param
-          {}  # no-op
+        when :path, :param
+          {}
         when :header
           {
             Grape::Http::Headers::HTTP_ACCEPT => [