Handle preview_paths in Rails 7.1

Author: JonRowe

example_app_generator/spec/support/default_preview_path

@@ -43,9 +43,12 @@ require_file_stub 'config/environment' do
 
         # Don't care if the mailer can't send.
         config.action_mailer.raise_delivery_errors = false unless ENV['NO_ACTION_MAILER']
-
         if ENV['CUSTOM_PREVIEW_PATH']
-          config.action_mailer.preview_path = ENV['CUSTOM_PREVIEW_PATH']
+          if Rails::VERSION::STRING.start_with?('7.1')
+            config.action_mailer.preview_paths = [ENV['CUSTOM_PREVIEW_PATH']]
+          else
+            config.action_mailer.preview_path = ENV['CUSTOM_PREVIEW_PATH']
+          end
         end
         if ENV['SHOW_PREVIEWS']
           config.action_mailer.show_previews = (ENV['SHOW_PREVIEWS'] == 'true')
@@ -66,7 +69,11 @@ exit if ENV['NO_ACTION_MAILER']
 if ENV['DEFAULT_URL']
   puts ActionMailer::Base.default_url_options[:host]
 elsif defined?(::ActionMailer::Preview)
-  puts Rails.application.config.action_mailer.preview_path
+  if Rails::VERSION::STRING.start_with?('7.1')
+    puts Rails.application.config.action_mailer.preview_paths
+  else
+    puts Rails.application.config.action_mailer.preview_path
+  end
 end
 
 # This will force the loading of ActionMailer settings to ensure we do not

example_app_generator/spec/verify_mailer_preview_path_spec.rb

@@ -30,12 +30,26 @@ def capture_exec(*ops)
     CaptureExec.new(out, $?.exitstatus)
   end
 
-  def have_no_preview
-    have_attributes(io: be_blank, exit_status: 0)
-  end
+  if Rails::VERSION::STRING.start_with?('7.1')
+    let(:expected_custom_path) { "/custom/path\n#{::Rails.root}/test/mailers/previews" }
+    let(:expected_rspec_path) { "#{::Rails.root}/spec/mailers/previews\n#{::Rails.root}/test/mailers/previews" }
+
+    def have_no_preview(opts = {})
+      expected_io =
+        if opts[:actually_blank]
+          be_blank
+        else
+          "#{::Rails.root}/test/mailers/previews"
+        end
+      have_attributes(io: expected_io, exit_status: 0)
+    end
+  else
+    let(:expected_custom_path) { '/custom/path' }
+    let(:expected_rspec_path) { "#{::Rails.root}/spec/mailers/previews" }
 
-  before do
-    skip("Currently broken for unknown reasons")
+    def have_no_preview(_opts = {})
+      have_attributes(io: be_blank, exit_status: 0)
+    end
   end
 
   let(:exec_script) {
@@ -49,9 +63,7 @@ def have_no_preview
 
       it 'sets the preview path to the default rspec path' do
         skip "this spec fails singularly on JRuby due to weird env things" if RUBY_ENGINE == "jruby"
-        expect(capture_exec(custom_env, exec_script)).to eq(
-          "#{::Rails.root}/spec/mailers/previews"
-        )
+        expect(capture_exec(custom_env, exec_script)).to eq(expected_rspec_path)
       end
 
       it 'respects the setting from `show_previews`' do
@@ -69,7 +81,7 @@ def have_no_preview
             custom_env.merge('CUSTOM_PREVIEW_PATH' => '/custom/path'),
             exec_script
           )
-        ).to eq('/custom/path')
+        ).to eq(expected_custom_path)
       end
 
       it 'allows initializers to set options' do
@@ -87,7 +99,7 @@ def have_no_preview
             custom_env.merge('NO_ACTION_MAILER' => 'true'),
             exec_script
           )
-        ).to have_no_preview
+        ).to have_no_preview(actually_blank: true)
       end
     end
 
@@ -102,7 +114,7 @@ def have_no_preview
       it 'respects the setting from `show_previews`' do
         expect(
           capture_exec(custom_env.merge('SHOW_PREVIEWS' => 'true'), exec_script)
-        ).to eq("#{::Rails.root}/spec/mailers/previews")
+        ).to eq(expected_rspec_path)
       end
 
       it 'allows initializers to set options' do

lib/rspec-rails.rb

@@ -47,10 +47,18 @@ def config_preview_path?(options)
         end
       end
 
-      def config_default_preview_path(options)
-        return unless options.preview_path.blank?
+      if ::Rails::VERSION::STRING >= "7.1.0"
+        def config_default_preview_path(options)
+          return unless options.preview_paths.empty?
 
-        options.preview_path = "#{::Rails.root}/spec/mailers/previews"
+          options.preview_paths << "#{::Rails.root}/spec/mailers/previews"
+        end
+      else
+        def config_default_preview_path(options)
+          return unless options.preview_path.blank?
+
+          options.preview_path = "#{::Rails.root}/spec/mailers/previews"
+        end
       end
 
       def supports_action_mailer_previews?(config)