Integration Test: use response helper

Access `response.body` through `response` helper method instead of
directly reading from the `@response` instance variable.

test/drive/drive_helper_test.rb

@@ -3,11 +3,11 @@
 class Turbo::DriveHelperTest < ActionDispatch::IntegrationTest
   test "opting out of the default cache" do
     get trays_path
-    assert_match(/<meta name="turbo-cache-control" content="no-cache">/, @response.body)
+    assert_match(/<meta name="turbo-cache-control" content="no-cache">/, response.body)
   end
 
   test "requiring reload" do
     get trays_path
-    assert_match(/<meta name="turbo-visit-control" content="reload">/, @response.body)
+    assert_match(/<meta name="turbo-visit-control" content="reload">/, response.body)
   end
 end

test/frames/frame_request_controller_test.rb

@@ -11,10 +11,10 @@ class Turbo::FrameRequestControllerTest < ActionDispatch::IntegrationTest
 
   test "frame requests get a unique etag" do
     get tray_path(id: 1)
-    etag_without_frame = @response.headers["ETag"]
+    etag_without_frame = response.headers["ETag"]
 
     get tray_path(id: 1), headers: { "Turbo-Frame" => "true" }
-    etag_with_frame = @response.headers["ETag"]
+    etag_with_frame = response.headers["ETag"]
 
     assert_not_equal etag_with_frame, etag_without_frame
   end
@@ -23,9 +23,9 @@ class Turbo::FrameRequestControllerTest < ActionDispatch::IntegrationTest
     turbo_frame_request_id = "test_frame_id"
 
     get tray_path(id: 1)
-    assert_no_match /#{turbo_frame_request_id}/, @response.body
+    assert_no_match /#{turbo_frame_request_id}/, response.body
 
     get tray_path(id: 1), headers: { "Turbo-Frame" => turbo_frame_request_id }
-    assert_match /#{turbo_frame_request_id}/, @response.body
+    assert_match /#{turbo_frame_request_id}/, response.body
   end
 end

test/streams/streams_controller_test.rb

@@ -18,7 +18,7 @@ class Turbo::StreamsControllerTest < ActionDispatch::IntegrationTest
 
     get message_path(id: 1), as: :turbo_stream
 
-    assert_dom_equal <<~HTML, @response.body
+    assert_dom_equal <<~HTML, response.body
       <turbo-stream action="remove" target="message_1"></turbo-stream>
       <turbo-stream action="replace" target="message_1"><template>#{render(message_1)}</template></turbo-stream>
       <turbo-stream action="replace" target="message_1"><template>Something else</template></turbo-stream>
@@ -40,7 +40,7 @@ class Turbo::StreamsControllerTest < ActionDispatch::IntegrationTest
     assert_turbo_stream action: :replace, targets: "#message_4" do
       assert_select 'template', 'Something fourth'
     end
-    assert_dom_equal <<~HTML, @response.body
+    assert_dom_equal <<~HTML, response.body
       <turbo-stream action="remove" targets="#message_1"></turbo-stream>
       <turbo-stream action="replace" targets="#message_1"><template>#{render(message_1)}</template></turbo-stream>
       <turbo-stream action="replace" targets="#message_1"><template>Something else</template></turbo-stream>
@@ -55,7 +55,7 @@ class Turbo::StreamsControllerTest < ActionDispatch::IntegrationTest
 
   test "includes html format when rendering turbo_stream actions" do
     post posts_path, as: :turbo_stream
-    assert_dom_equal <<~HTML.chomp, @response.body
+    assert_dom_equal <<~HTML.chomp, response.body
       <turbo-stream action="update" target="form-area"><template>
         Form
       </template></turbo-stream>
@@ -64,15 +64,15 @@ class Turbo::StreamsControllerTest < ActionDispatch::IntegrationTest
 
   test "render correct partial for namespaced models" do
     get users_profile_path(id: 1), as: :turbo_stream
-    assert_dom_equal <<~HTML, @response.body.remove(/\n(?=<\/)/)
+    assert_dom_equal <<~HTML, response.body.remove(/\n(?=<\/)/)
       <turbo-stream action="replace" target="users_profile_1"><template><p>David</p></template></turbo-stream>
       <turbo-stream action="update" target="users_profile_1"><template><p>David</p></template></turbo-stream>
     HTML
   end
 
   test "render correct partial and I18n with a custom view path in the controller" do
     get admin_company_path(id: 1), as: :turbo_stream
-    assert_dom_equal <<~HTML, @response.body.remove(/\n(?=<\/)/)
+    assert_dom_equal <<~HTML, response.body.remove(/\n(?=<\/)/)
       <turbo-stream action="replace" target="company_1"><template><p>Company:</p>
       <p>Basecamp</p></template></turbo-stream>
     HTML