Do not set Content-Type for DELETE requests

Neither GET nor DELETE support the Content-Type header, so setting it to
application/x-www-form-urlencoded messes with some web frameworks
(including my own) in the test suite. This patch makes sure that
Content-Type is not automatically set for DELETE requests.

Signed-off-by: David Celis <me@davidcel.is>

lib/rack/test.rb

@@ -205,7 +205,7 @@ def env_for(path, env)
         # Stringifying and upcasing methods has be commit upstream
         env["REQUEST_METHOD"] ||= env[:method] ? env[:method].to_s.upcase : "GET"
 
-        if env["REQUEST_METHOD"] == "GET"
+        if ["GET", "DELETE"].include?(env["REQUEST_METHOD"])
           # merge :params with the query string
           if params = env[:params]
             params = parse_nested_query(params) if params.is_a?(String)

spec/rack/test_spec.rb

@@ -540,6 +540,12 @@ def verb
   describe "#delete" do
     it_should_behave_like "any #verb methods"
 
+    it "does not set a content type" do
+      delete "/"
+
+      last_request.env['HTTP_CONTENT_TYPE'].should be_nil
+    end
+
     def verb
       "delete"
     end