diff --git a/actionpack/test/controller/mime/respond_to_test.rb b/actionpack/test/controller/mime/respond_to_test.rb
index 993f4001de..d113db8b76 100644
--- a/actionpack/test/controller/mime/respond_to_test.rb
+++ b/actionpack/test/controller/mime/respond_to_test.rb
@@ -104,7 +104,7 @@ def made_for_content_type
   def custom_type_handling
     respond_to do |type|
       type.html { render body: "HTML"    }
-      type.custom("application/crazy-xml")  { render body: "Crazy XML"  }
+      type.custom("application/fancy-xml")  { render body: "Fancy XML"  }
       type.all  { render body: "Nothing" }
     end
   end
@@ -294,12 +294,14 @@ def setup
     @request.host = "www.example.com"
     Mime::Type.register_alias("text/html", :iphone)
     Mime::Type.register("text/x-mobile", :mobile)
+    Mime::Type.register("application/fancy-xml", :fancy_xml)
   end
 
   def teardown
     super
     Mime::Type.unregister(:iphone)
     Mime::Type.unregister(:mobile)
+    Mime::Type.unregister(:fancy_xml)
   end
 
   def test_html
@@ -455,10 +457,10 @@ def test_synonyms
   end
 
   def test_custom_types
-    @request.accept = "application/crazy-xml"
+    @request.accept = "application/fancy-xml"
     get :custom_type_handling
-    assert_equal "application/crazy-xml", @response.content_type
-    assert_equal 'Crazy XML', @response.body
+    assert_equal "application/fancy-xml", @response.content_type
+    assert_equal "Fancy XML", @response.body
 
     @request.accept = "text/html"
     get :custom_type_handling
diff --git a/actionpack/test/controller/new_base/content_negotiation_test.rb b/actionpack/test/controller/new_base/content_negotiation_test.rb
index c0e92b3b05..b867bcd675 100644
--- a/actionpack/test/controller/new_base/content_negotiation_test.rb
+++ b/actionpack/test/controller/new_base/content_negotiation_test.rb
@@ -19,9 +19,19 @@ class TestContentNegotiation < Rack::TestCase
       assert_body "Hello world */*!"
     end
 
-    test "Not all mimes are converted to symbol" do
+    test "A js or */* Accept header will return HTML" do
+      get "/content_negotiation/basic/hello", headers: { "HTTP_ACCEPT" => "text/javascript, */*" }
+      assert_body "Hello world text/html!"
+    end
+
+    test "A js or */* Accept header on xhr will return HTML" do
+      get "/content_negotiation/basic/hello", headers: { "HTTP_ACCEPT" => "text/javascript, */*" }, xhr: true
+      assert_body "Hello world text/javascript!"
+    end
+
+    test "Unregistered mimes are ignored" do
       get "/content_negotiation/basic/all", headers: { "HTTP_ACCEPT" => "text/plain, mime/another" }
-      assert_body '[:text, "mime/another"]'
+      assert_body '[:text]'
     end
   end
 end