Stop setting a default Capybara app host

It's intended not to be set if Capybara starts the app server itself. Base Rails-generated URLs off of Capybara.current_session.server_url instead.

4 files changed, 38 insertions, 33 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 9a6bd4bb45..99a4ac6845 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   System tests require Capybara 3.26 or newer.
+
+    *George Claghorn*
+
 *   Reduced log noise handling ActionController::RoutingErrors.
 
     *Alberto Fernández-Capel*
diff --git a/actionpack/lib/action_dispatch/system_test_case.rb b/actionpack/lib/action_dispatch/system_test_case.rb
index 4fda2cf44f..aae96975c7 100644
--- a/actionpack/lib/action_dispatch/system_test_case.rb
+++ b/actionpack/lib/action_dispatch/system_test_case.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-gem "capybara", ">= 2.15"
+gem "capybara", ">= 3.26"
 
 require "capybara/dsl"
 require "capybara/minitest"
@@ -119,17 +119,6 @@ module ActionDispatch
     def initialize(*) # :nodoc:
       super
       self.class.driver.use
-      @proxy_route = if ActionDispatch.test_app
-        Class.new do
-          include ActionDispatch.test_app.routes.url_helpers
-
-          def url_options
-            default_url_options.merge(host: Capybara.app_host)
-          end
-        end.new
-      else
-        nil
-      end
     end
 
     def self.start_application # :nodoc:
@@ -170,16 +159,33 @@ module ActionDispatch
 
     driven_by :selenium
 
-    def method_missing(method, *args, &block)
-      if @proxy_route.respond_to?(method)
-        @proxy_route.send(method, *args, &block)
-      else
-        super
+    private
+      def url_helpers
+        @url_helpers ||=
+          if ActionDispatch.test_app
+            Class.new do
+              include ActionDispatch.test_app.routes.url_helpers
+
+              def url_options
+                default_url_options.reverse_merge(host: Capybara.app_host || Capybara.current_session.server_url)
+              end
+            end.new
+          end
       end
-    end
 
-    ActiveSupport.run_load_hooks(:action_dispatch_system_test_case, self)
-  end
+      def method_missing(name, *args, &block)
+        if url_helpers.respond_to?(name)
+          url_helpers.public_send(name, *args, &block)
+        else
+          super
+        end
+      end
 
-  SystemTestCase.start_application
+      def respond_to_missing?(name, include_private = false)
+        url_helpers.respond_to?(name)
+      end
+  end
 end
+
+ActiveSupport.run_load_hooks :action_dispatch_system_test_case, ActionDispatch::SystemTestCase
+ActionDispatch::SystemTestCase.start_application
diff --git a/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb b/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb
index 20f6a7634f..30dc21ebb9 100644
--- a/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb
+++ b/actionpack/lib/action_dispatch/system_testing/test_helpers/setup_and_teardown.rb
@@ -4,15 +4,12 @@ module ActionDispatch
   module SystemTesting
     module TestHelpers
       module SetupAndTeardown # :nodoc:
-        DEFAULT_HOST = "http://127.0.0.1"
-
         def host!(host)
-          Capybara.app_host = host
-        end
+          ActiveSupport::Deprecation.warn \
+            "ActionDispatch::SystemTestCase#host! is deprecated with no replacement. " \
+            "Set Capybara.app_host directly or rely on Capybara's default host."
 
-        def before_setup
-          host! DEFAULT_HOST
-          super
+          Capybara.app_host = host
         end
 
         def before_teardown
diff --git a/actionpack/test/dispatch/system_testing/system_test_case_test.rb b/actionpack/test/dispatch/system_testing/system_test_case_test.rb
index 3319db1665..d235f7ad89 100644
--- a/actionpack/test/dispatch/system_testing/system_test_case_test.rb
+++ b/actionpack/test/dispatch/system_testing/system_test_case_test.rb
@@ -36,12 +36,10 @@ class SetDriverToSeleniumHeadlessFirefoxTest < DrivenBySeleniumWithHeadlessFiref
 end
 
 class SetHostTest < DrivenByRackTest
-  test "sets default host" do
-    assert_equal "http://127.0.0.1", Capybara.app_host
-  end
-
   test "overrides host" do
-    host! "http://example.com"
+    assert_deprecated do
+      host! "http://example.com"
+    end
 
     assert_equal "http://example.com", Capybara.app_host
   end