Decorate responses from Rack Middleware and Rails Metal for the purposes of integration testing. A test for the following Metal:

class Poller < Rails::Rack::Metal
      def call(env)
        if env["PATH_INFO"] =~ /^\/poller/
          [200, {"Content-Type" => "text/plain"}, "Hello World!"]
        else
          super
        end
      end
    end

might be tested like so:

  class PollerTest < ActionController::IntegrationTest
    test "poller returns hello world" do
      get "/poller"
      assert_response 200
      assert_response :success
      assert_response :ok
      assert_equal "Hello World!", response.body
    end
  end

[#1588 state:committed]

Signed-off-by: David Heinemeier Hansson <david@loudthinking.com>

actionpack/lib/action_controller/integration.rb

@@ -276,6 +276,7 @@ module ActionController
             "SCRIPT_NAME"     => "",
 
             "REQUEST_URI"    => path,
+            "PATH_INFO"      => path,
             "HTTP_HOST"      => host,
             "REMOTE_ADDR"    => remote_addr,
             "CONTENT_TYPE"   => "application/x-www-form-urlencoded",
@@ -310,16 +311,6 @@ module ActionController
           status, headers, body = app.call(env)
           @request_count += 1
 
-          if @controller = ActionController::Base.last_instantiation
-            @request = @controller.request
-            @response = @controller.response
-
-            # Decorate the response with the standard behavior of the
-            # TestResponse so that things like assert_response can be
-            # used in integration tests.
-            @response.extend(TestResponseBehavior)
-          end
-
           @html_document = nil
 
           @status = status.to_i
@@ -335,6 +326,22 @@ module ActionController
           @body = ""
           body.each { |part| @body << part }
 
+          if @controller = ActionController::Base.last_instantiation
+            @request = @controller.request
+            @response = @controller.response
+          else
+            # Decorate responses from Rack Middleware and Rails Metal
+            # as an AbstractResponse for the purposes of integration testing
+            @response = AbstractResponse.new
+            @response.headers = @headers.merge('Status' => status.to_s)
+            @response.body = @body
+          end
+
+          # Decorate the response with the standard behavior of the
+          # TestResponse so that things like assert_response can be
+          # used in integration tests.
+          @response.extend(TestResponseBehavior)
+
           return @status
         rescue MultiPartNeededException
           boundary = "----------XnJLe9ZIbbGUYtzPQJ16u1"

actionpack/test/controller/integration_test.rb

@@ -373,4 +373,39 @@ class IntegrationProcessTest < ActionController::IntegrationTest
     end
 end
 
+class MetalTest < ActionController::IntegrationTest
+  require(File.dirname(__FILE__) + "/../../../railties/lib/rails/rack/metal.rb")
+
+  class Poller < ::Rails::Rack::Metal
+    def call(env)
+      if env["PATH_INFO"] =~ /^\/success/
+        [200, {"Content-Type" => "text/plain"}, "Hello World!"]
+      elsif env["PATH_INFO"] =~ /^\/failure/
+        [404, {"Content-Type" => "text/plain"}, '']
+      else
+        super
+      end
+    end
+  end
+
+  def setup
+    @integration_session = ActionController::Integration::Session.new(Poller)
+  end
+
+  def test_successful_get
+    get "/success"
+    assert_response 200
+    assert_response :success
+    assert_response :ok
+    assert_equal "Hello World!", response.body
+  end
+
+  def test_failed_get
+    get "/failure"
+    assert_response 404
+    assert_response :not_found
+    assert_equal '', response.body
+  end
+end
+
 end