PERF: hijack onebox requests so they do not use up a unicorn worker

spec/components/hijack_spec.rb

@@ -0,0 +1,70 @@
+require 'rails_helper'
+
+describe Hijack do
+  class Hijack::Tester
+    attr_reader :io
+
+    include Hijack
+    def initialize
+      @io = StringIO.new
+    end
+
+    def hijack_test(&blk)
+      hijack do
+        self.instance_eval(&blk)
+      end
+    end
+
+    def request
+      @req ||= ActionController::TestRequest.new(
+        { "rack.hijack" => lambda { @io } },
+        nil,
+        nil
+      )
+    end
+
+    def render(*opts)
+      # don't care
+    end
+  end
+
+  let :tester do
+    Hijack::Tester.new
+  end
+
+  it "renders non 200 status if asked for" do
+    tester.hijack_test do
+      render body: "hello world", status: 402
+    end
+
+    expect(tester.io.string).to include("402")
+    expect(tester.io.string).to include("world")
+  end
+
+  it "renders stuff correctly if it works" do
+    tester.hijack_test do
+      render plain: "hello world"
+    end
+
+    result = "HTTP/1.1 200 OK\r\nContent-Length: 11\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\nhello world"
+    expect(tester.io.string).to eq(result)
+  end
+
+  it "returns 500 by default" do
+    tester.hijack_test
+
+    expected = "HTTP/1.1 500 OK\r\nContent-Length: 0\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\n"
+    expect(tester.io.string).to eq(expected)
+  end
+
+  it "does not run the block if io is closed" do
+    tester.io.close
+
+    ran = false
+    tester.hijack_test do
+      ran = true
+    end
+
+    expect(ran).to eq(false)
+  end
+end