Move Transfer-Encoding chunked test to Action Pack

While working on [another PR][1], I found that removing the
Transfer-Encoding conditionals did not result in any failing tests in
Action Pack. This was surprising to me until I found that there was a
test for this behavior in Railties. However, nothing about the test
really depends on having a full Rails application or the Railties test
suite.

This commit moves the test into Action Pack to simplify/speedup the test
(no need to build a full app) as well as keeping the test closer to the
actual behavior being tested.

[1]: 0c334b48fdc5d70b0c8406ba184fbfd26750b049

actionpack/test/controller/chunked_test.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+require "stringio"
+require "abstract_unit"
+
+class ChunkedTest < ActionDispatch::IntegrationTest
+  class ChunkedController < ApplicationController
+    def chunk
+      render json: {
+        raw_post: request.raw_post,
+        content_length: request.content_length
+      }
+    end
+  end
+
+  # The TestInput class prevents Rack::MockRequest from adding a Content-Length when the method `size` is defined
+  class TestInput < StringIO
+    undef_method :size
+  end
+
+  test "parses request raw_post correctly when request has Transfer-Encoding header without a Content-Length value" do
+    @app = self.class.build_app
+    @app.routes.draw do
+      post "chunked", to: ChunkedController.action(:chunk)
+    end
+
+    post "/chunked", params: TestInput.new("foo=bar"), headers: { "Transfer-Encoding" => "gzip, chunked;foo=bar" }
+
+    assert_equal 7, response.parsed_body["content_length"]
+    assert_equal "foo=bar", response.parsed_body["raw_post"]
+  end
+end

railties/test/railties/http_request_test.rb

@@ -1,54 +0,0 @@
-# frozen_string_literal: true
-
-require "isolation/abstract_unit"
-require "stringio"
-require "rack/test"
-require "active_support/core_ext/module/delegation"
-
-module RailtiesTest
-  class HttpRequestTest < ActiveSupport::TestCase
-    include ActiveSupport::Testing::Isolation
-    include Rack::Test::Methods
-
-    def setup
-      build_app
-
-      app_file "config/routes.rb", <<-RUBY
-        Rails.application.routes.draw do
-          post "posts", to: "posts#create"
-        end
-      RUBY
-
-      controller "posts", <<-RUBY
-        class PostsController < ApplicationController
-          def create
-            render json: {
-              raw_post: request.raw_post,
-              content_length: request.content_length
-            }
-          end
-        end
-      RUBY
-    end
-
-    def teardown
-      teardown_app
-    end
-
-    # The TestInput class prevents Rack::MockRequest from adding a Content-Length when the method `size` is defined
-    class TestInput < StringIO
-      undef_method :size
-    end
-
-    test "parses request raw_post correctly when request has Transfer-Encoding header without a Content-Length value" do
-      require "#{app_path}/config/environment"
-
-      header "Transfer-Encoding", "gzip, chunked;foo=bar"
-      post "/posts", TestInput.new("foo=bar")
-
-      json_response = JSON.parse(last_response.body)
-      assert_equal 7, json_response["content_length"]
-      assert_equal "foo=bar", json_response["raw_post"]
-    end
-  end
-end