diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000000..5f5738a00e
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,106 @@
+name: RSpec CI
+on:
+  push:
+    branches:
+      - 'main'
+      - '*-maintenance'
+      - '*-dev'
+  pull_request:
+    branches:
+      - '*'
+jobs:
+  test:
+    name: 'Ruby: ${{ matrix.ruby }}, Rails: ${{ matrix.env.RAILS_VERSION }}'
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: false
+      matrix:
+       include:
+         # Rails 6.1.0.rc1 builds >= 2.5.0
+         - ruby: 3.0.0-preview1
+           env:
+             RAILS_VERSION: '6.1.0.rc1'
+         - ruby: 2.7
+           env:
+             RAILS_VERSION: '6.1.0.rc1'
+         - ruby: 2.6
+           env:
+             RAILS_VERSION: '6.1.0.rc1'
+         - ruby: 2.5
+           env:
+             RAILS_VERSION: '6.1.0.rc1'
+         # Rails 6.0 builds >= 2.5.0
+         - ruby: 3.0.0-preview1
+           env:
+             RAILS_VERSION: '~> 6.0.0'
+         - ruby: 2.7
+           env:
+             RAILS_VERSION: '~> 6.0.0'
+         - ruby: 2.6
+           env:
+             RAILS_VERSION: '~> 6.0.0'
+         - ruby: 2.5
+           env:
+             RAILS_VERSION: '~> 6.0.0'
+         # Rails 5.2 builds >= 2.2.2
+         - ruby: 2.6.6
+           env:
+             RAILS_VERSION: '~> 5.2.0'
+         - ruby: 2.5.8
+           env:
+             RAILS_VERSION: '~> 5.2.0'
+         - ruby: 2.4.10
+           env:
+             RAILS_VERSION: '~> 5.2.0'
+         - ruby: 2.3.8
+           env:
+             RAILS_VERSION: '~> 5.2.0'
+         - ruby: 2.2.10
+           allow_failure: true
+           env:
+             RAILS_VERSION: '~> 5.2.0'
+         - ruby: 2.2.10
+           env:
+             RAILS_VERSION: '5-2-stable'
+         # Rails 5.1 Builds >= 2.2.2
+         - ruby: 2.6.6
+           env:
+             RAILS_VERSION: '~> 5.1.0'
+         - ruby: 2.5.8
+           env:
+             RAILS_VERSION: '~> 5.1.0'
+         - ruby: 2.4.10
+           env:
+             RAILS_VERSION: '~> 5.1.0'
+         - ruby: 2.3.8
+           env:
+             RAILS_VERSION: '~> 5.1.0'
+         - ruby: 2.2.10
+           env:
+             RAILS_VERSION: '~> 5.1.0'
+         # Rails 5.0 Builds >= 2.2.2
+         - ruby: 2.6.6
+           env:
+             RAILS_VERSION: '~> 5.0.0'
+         - ruby: 2.5.8
+           env:
+             RAILS_VERSION: '~> 5.0.0'
+         - ruby: 2.4.10
+           env:
+             RAILS_VERSION: '~> 5.0.0'
+         - ruby: 2.3.8
+           env:
+             RAILS_VERSION: '~> 5.0.0'
+         - ruby: 2.2.10
+           env:
+             RAILS_VERSION: '~> 5.0.0'
+    env: ${{ matrix.env }}
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+      - run: script/clone_all_rspec_repos
+      - run: bundle install --binstubs
+      - run: script/run_build
+        continue-on-error: ${{ matrix.allow_failure || false }}
diff --git a/.travis.yml b/.travis.yml
index a88f9ffd4f..724132d32b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -38,82 +38,31 @@ script: "script/run_build 2>&1"
 
 matrix:
   include:
-    # Rails 6.1 builds >= 2.5
-    - rvm: ruby-3.0.0-preview1
-      env: RAILS_VERSION='master'
-      allow_failure: true
-    - rvm: 2.7.1
-      env: RAILS_VERSION='master'
-    - rvm: 2.6.6
-      env: RAILS_VERSION='master'
-    - rvm: 2.5.8
-      env: RAILS_VERSION='master'
+    - rvm: jruby-head
       jdk: oraclejdk11
       env:
-        - RAILS_VERSION='master'
+        - RAILS_VERSION='6.1.0.rc1'
         - JRUBY_OPT=--dev
         - JAVA_OPTS="--add-opens java.base/sun.nio.ch=org.jruby.dist --add-opens java.base/java.io=org.jruby.dist --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.security.cert=ALL-UNNAMED --add-opens=java.base/java.util.zip=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.base/java.util.regex=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED  --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/javax.crypto=ALL-UNNAMED --add-opens=java.management/sun.management=ALL-UNNAMED"
 
-    # Rails 6.0 builds >= 2.5.0
     - rvm: jruby-head
       jdk: oraclejdk11
       env:
         - RAILS_VERSION='~> 6.0.0'
         - JRUBY_OPT=--dev
         - JAVA_OPTS="--add-opens java.base/sun.nio.ch=org.jruby.dist --add-opens java.base/java.io=org.jruby.dist --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.security.cert=ALL-UNNAMED --add-opens=java.base/java.util.zip=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.base/java.util.regex=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED  --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/javax.crypto=ALL-UNNAMED --add-opens=java.management/sun.management=ALL-UNNAMED"
-    - rvm: ruby-3.0.0-preview1
-      env: RAILS_VERSION='~> 6.0.0'
-      allow_failure: true
-    - rvm: 2.7.1
-      env: RAILS_VERSION='~> 6.0.0'
-    - rvm: 2.6.6
-      env: RAILS_VERSION='~> 6.0.0'
-    - rvm: 2.5.8
-      env: RAILS_VERSION='~> 6.0.0'
 
-    # Rails 5.2 builds >= 2.2.2
     - rvm: jruby-head
       jdk: oraclejdk11
       env:
         - RAILS_VERSION='~> 5.2.0'
         - JRUBY_OPT=--dev
         - JAVA_OPTS="--add-opens java.base/sun.nio.ch=org.jruby.dist --add-opens java.base/java.io=org.jruby.dist --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.security.cert=ALL-UNNAMED --add-opens=java.base/java.util.zip=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.base/java.util.regex=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED  --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/javax.crypto=ALL-UNNAMED --add-opens=java.management/sun.management=ALL-UNNAMED"
-    - rvm: 2.6.6
-      env: RAILS_VERSION='~> 5.2.0'
-    - rvm: 2.5.8
-      env: RAILS_VERSION='~> 5.2.0'
-    - rvm: 2.4.10
-      env: RAILS_VERSION='~> 5.2.0'
-    - rvm: 2.3.8
-      env: RAILS_VERSION='~> 5.2.0'
-    - rvm: 2.2.10
-      env: RAILS_VERSION='~> 5.2.0'
-      allow_failure: true
-    - rvm: 2.2.10
-      env: RAILS_VERSION='5-2-stable'
-
-    # Rails 5.1 Builds >= 2.2.2
-    - rvm: 2.6.6
-      env: RAILS_VERSION='~> 5.1.0'
-    - rvm: 2.5.8
-      env: RAILS_VERSION='~> 5.1.0'
-    - rvm: 2.4.10
-      env: RAILS_VERSION='~> 5.1.0'
-    - rvm: 2.3.8
-      env: RAILS_VERSION='~> 5.1.0'
-    - rvm: 2.2.10
-      env: RAILS_VERSION='~> 5.1.0'
-
-    # Rails 5.0 Builds >= 2.2.2
-    - rvm: 2.6.6
-      env: RAILS_VERSION='~> 5.0.0'
-    - rvm: 2.5.8
-      env: RAILS_VERSION='~> 5.0.0'
-    - rvm: 2.4.10
-      env: RAILS_VERSION='~> 5.0.0'
-    - rvm: 2.3.8
-      env: RAILS_VERSION='~> 5.0.0'
-    - rvm: 2.2.10
-      env: RAILS_VERSION='~> 5.0.0'
 
   fast_finish: true
+
+branches:
+  only:
+    - master
+    - /^\d+-\d+-maintenance$/
+    - /^\d+-\d+-dev$/
diff --git a/Changelog.md b/Changelog.md
index b282cf44b0..06fa41d24c 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -14,6 +14,8 @@ Enhancements:
   (Eloy Espinaco, Luka Lüdicke, #2355, #2356, #2378)
 * Generated scaffold now includes engine route helpers when inside a mountable engine.
   (Andrew W. Lee, #2372)
+* Improve request spec "controller" scafold when no action is specified.
+  (Thomas Hareau, #2399)
 
 Bug Fixes:
 
diff --git a/example_app_generator/generate_action_mailer_specs.rb b/example_app_generator/generate_action_mailer_specs.rb
index 13a1f0a4c0..c8034a8de4 100644
--- a/example_app_generator/generate_action_mailer_specs.rb
+++ b/example_app_generator/generate_action_mailer_specs.rb
@@ -14,15 +14,9 @@
       end
     end
   CODE
-  gsub_file 'config/initializers/action_mailer.rb',
-            /ExampleApp/,
-            Rails.application.class.parent.to_s
 
   copy_file 'spec/support/default_preview_path'
   chmod 'spec/support/default_preview_path', 0755
-  gsub_file 'spec/support/default_preview_path',
-            /ExampleApp/,
-            Rails.application.class.parent.to_s
   if skip_active_record?
     comment_lines 'spec/support/default_preview_path', /active_record/
     comment_lines 'spec/support/default_preview_path', /active_storage/
diff --git a/features/controller_specs/anonymous_controller.feature b/features/controller_specs/anonymous_controller.feature
index 7892b4dfac..9baf73fb8d 100644
--- a/features/controller_specs/anonymous_controller.feature
+++ b/features/controller_specs/anonymous_controller.feature
@@ -101,6 +101,8 @@ Feature: anonymous controller
     When I run `rspec spec`
     Then the examples should all pass
 
+  # Deprecated support removed in https://github.com/rails/rails/commit/d52d7739468153bd6cb7c629f60bd5cd7ebea3eb
+  @rails_pre_6
   Scenario: Specify error handling in `ApplicationController` with render :file
     Given a file named "spec/controllers/application_controller_spec.rb" with:
       """ruby
diff --git a/features/matchers/have_broadcasted_matcher.feature b/features/matchers/have_broadcasted_matcher.feature
index ecacadafe9..8b639326ac 100644
--- a/features/matchers/have_broadcasted_matcher.feature
+++ b/features/matchers/have_broadcasted_matcher.feature
@@ -16,7 +16,7 @@ Feature: have_broadcasted matcher
         it "matches with stream name" do
           expect {
             ActionCable.server.broadcast(
-              "notifications", text: 'Hello!'
+              "notifications", { text: "Hello!" }
             )
           }.to have_broadcasted_to("notifications")
         end
@@ -34,7 +34,7 @@ Feature: have_broadcasted matcher
         it "matches with message" do
           expect {
             ActionCable.server.broadcast(
-              "notifications", text: 'Hello!'
+              "notifications", { text: "Hello!" }
             )
           }.to have_broadcasted_to("notifications").with(text: 'Hello!')
         end
@@ -52,7 +52,7 @@ Feature: have_broadcasted matcher
         it "matches with message" do
           expect {
             ActionCable.server.broadcast(
-              "notifications", text: 'Hello!', user_id: 12
+              "notifications", { text: 'Hello!', user_id: 12 }
             )
           }.to have_broadcasted_to("notifications").with(a_hash_including(text: 'Hello!'))
         end
@@ -70,7 +70,7 @@ Feature: have_broadcasted matcher
         it "matches with message" do
           expect {
             ActionCable.server.broadcast(
-              "notifications", text: 'Hello!', user_id: 12
+              "notifications", { text: 'Hello!', user_id: 12 }
             )
           }.to have_broadcasted_to("notifications").with { |data|
             expect(data['user_id']).to eq 12
@@ -90,7 +90,7 @@ Feature: have_broadcasted matcher
         it "matches with stream name" do
           expect {
             ActionCable.server.broadcast(
-              "notifications", text: 'Hello!'
+              "notifications", { text: 'Hello!' }
             )
           }.to broadcast_to("notifications")
         end
diff --git a/lib/generators/rspec/controller/templates/request_spec.rb b/lib/generators/rspec/controller/templates/request_spec.rb
index 42b4b8e01b..75c5fc129a 100644
--- a/lib/generators/rspec/controller/templates/request_spec.rb
+++ b/lib/generators/rspec/controller/templates/request_spec.rb
@@ -1,7 +1,12 @@
 require 'rails_helper'
 
 RSpec.describe "<%= class_name.pluralize %>", <%= type_metatag(:request) %> do
-<% namespaced_path = regular_class_path.join('/') %>
+<% namespaced_path = regular_class_path.join('/') -%>
+<% if actions.empty? -%>
+  describe "GET /index" do
+    pending "add some examples (or delete) #{__FILE__}"
+  end
+<% end -%>
 <% for action in actions -%>
   describe "GET /<%= action %>" do
     it "returns http success" do
diff --git a/lib/rspec/rails/example/mailbox_example_group.rb b/lib/rspec/rails/example/mailbox_example_group.rb
index 24cd125b60..de85acdf43 100644
--- a/lib/rspec/rails/example/mailbox_example_group.rb
+++ b/lib/rspec/rails/example/mailbox_example_group.rb
@@ -13,7 +13,7 @@ module MailboxExampleGroup
         def self.create_inbound_email(arg)
           case arg
           when Hash
-            create_inbound_email_from_mail(arg)
+            create_inbound_email_from_mail(**arg)
           else
             create_inbound_email_from_source(arg.to_s)
           end
diff --git a/lib/rspec/rails/matchers/action_mailbox.rb b/lib/rspec/rails/matchers/action_mailbox.rb
index c5392cb225..de50c69143 100644
--- a/lib/rspec/rails/matchers/action_mailbox.rb
+++ b/lib/rspec/rails/matchers/action_mailbox.rb
@@ -22,11 +22,20 @@ def initialize(message)
             @inbound_email = create_inbound_email(message)
           end
 
-          def matches?(mailbox)
-            @mailbox  = mailbox
-            @receiver = ApplicationMailbox.router.send(:match_to_mailbox, inbound_email)
+          if defined?(::ApplicationMailbox) && ::ApplicationMailbox.router.respond_to?(:mailbox_for)
+            def matches?(mailbox)
+              @mailbox  = mailbox
+              @receiver = ApplicationMailbox.router.mailbox_for(inbound_email)
 
-            @receiver == @mailbox
+              @receiver == @mailbox
+            end
+          else
+            def matches?(mailbox)
+              @mailbox  = mailbox
+              @receiver = ApplicationMailbox.router.send(:match_to_mailbox, inbound_email)
+
+              @receiver == @mailbox
+            end
           end
 
           def failure_message
@@ -41,7 +50,7 @@ def failure_message_when_negated
             "expected #{describe_inbound_email} not to route to #{mailbox}"
           end
 
-        private
+          private
 
           attr_reader :inbound_email, :mailbox, :receiver
 
diff --git a/rspec-rails.gemspec b/rspec-rails.gemspec
index 237093112d..0f67a2c4f9 100644
--- a/rspec-rails.gemspec
+++ b/rspec-rails.gemspec
@@ -45,7 +45,9 @@ Gem::Specification.new do |s|
   # that we want. These will need to change from time to time as new RSpecs
   # get released.
   %w[core expectations mocks support].each do |name|
-    if RSpec::Rails::Version::STRING =~ /pre/ # prerelease builds
+    if ENV['RSPEC_CI']
+      s.add_runtime_dependency "rspec-#{name}", "= 4.0.0.pre"
+    elsif RSpec::Rails::Version::STRING =~ /pre/ # prerelease builds
       expected_rspec_version = "3.11.0.pre"
       s.add_runtime_dependency "rspec-#{name}", "= #{expected_rspec_version}"
     else
diff --git a/spec/generators/rspec/controller/controller_generator_spec.rb b/spec/generators/rspec/controller/controller_generator_spec.rb
index 8516703f23..4143af50fe 100644
--- a/spec/generators/rspec/controller/controller_generator_spec.rb
+++ b/spec/generators/rspec/controller/controller_generator_spec.rb
@@ -17,6 +17,7 @@
         it { is_expected.to exist }
         it { is_expected.to contain(/require 'rails_helper'/) }
         it { is_expected.to contain(/^RSpec.describe "Posts", #{type_metatag(:request)}/) }
+        it { is_expected.to contain('pending') }
       end
     end
 
diff --git a/spec/generators/rspec/scaffold/scaffold_generator_spec.rb b/spec/generators/rspec/scaffold/scaffold_generator_spec.rb
index a56b5858ea..d8417519f1 100644
--- a/spec/generators/rspec/scaffold/scaffold_generator_spec.rb
+++ b/spec/generators/rspec/scaffold/scaffold_generator_spec.rb
@@ -1,8 +1,10 @@
 # Generators are not automatically loaded by Rails
 require 'generators/rspec/scaffold/scaffold_generator'
 require 'support/generators'
+require 'rspec/support/spec/in_sub_process'
 
 RSpec.describe Rspec::Generators::ScaffoldGenerator, type: :generator do
+  include RSpec::Support::InSubProcess
   setup_default_destination
 
   describe 'standard request specs' do
@@ -41,12 +43,13 @@
     end
 
     describe 'in an engine' do
-      before do
-        allow_any_instance_of(::Rails::Generators::NamedBase).to receive(:mountable_engine?).and_return(true)
-        run_generator %w[posts --request_specs]
+      it 'generates files with Engine url_helpers' do
+        in_sub_process do
+          allow_any_instance_of(::Rails::Generators::NamedBase).to receive(:mountable_engine?).and_return(true)
+          run_generator %w[posts --request_specs]
+          is_expected.to contain('Engine.routes.url_helpers')
+        end
       end
-
-      it { is_expected.to contain('Engine.routes.url_helpers') }
     end
   end