[CLIENT] Improve code handling headers

Author: estolfo

elasticsearch-transport/lib/elasticsearch/transport/transport/base.rb

@@ -364,22 +364,26 @@ def host_unreachable_exceptions
         private
 
         USER_AGENT_STR = 'User-Agent'.freeze
+        USER_AGENT_REGEX = /user\-?\_?agent/
         CONTENT_TYPE_STR = 'Content-Type'.freeze
+        CONTENT_TYPE_REGEX = /content\-?\_?type/
+        DEFAULT_CONTENT_TYPE = 'application/json'.freeze
 
         def apply_headers(client, options)
-          headers = (options[:headers] || {}).inject({}) do |h, (k, v)|
-            if k.to_s.downcase =~ /content\-?\_?type/
-              h[CONTENT_TYPE_STR] = v
-            else
-              h[k] = v
-            end
-            h
-          end
-          headers[CONTENT_TYPE_STR] = 'application/json' unless headers[CONTENT_TYPE_STR]
-          headers[USER_AGENT_STR] = user_agent_header(client) unless headers[USER_AGENT_STR]
+          headers = options[:headers] || {}
+          headers[CONTENT_TYPE_STR] = find_key_value(headers, CONTENT_TYPE_REGEX) || DEFAULT_CONTENT_TYPE
+          headers[USER_AGENT_STR] = find_key_value(headers, USER_AGENT_REGEX) || user_agent_header(client)
           client.headers.merge!(headers)
         end
 
+        def find_key_value(hash, regex)
+          key_value = hash.find { |k,v| k.to_s.downcase =~ regex }
+          if key_value
+            hash.delete(key_value[0])
+            key_value[1]
+          end
+        end
+
         def user_agent_header(client)
           @user_agent ||= begin
             meta = ["RUBY_VERSION: #{RUBY_VERSION}"]

elasticsearch-transport/spec/elasticsearch/transport/client_spec.rb

@@ -72,6 +72,17 @@
     end
   end
 
+  context 'when a user-agent header is specified as client option in lower-case' do
+
+    let(:client) do
+      described_class.new(transport_options: { headers: { 'user-agent' => 'testing' } })
+    end
+
+    it 'sets the specified User-Agent header' do
+      expect(client.transport.connections.first.connection.headers['User-Agent']).to eq('testing')
+    end
+  end
+
   context 'when a Content-Type header is specified as client option' do
 
     let(:client) do
@@ -140,6 +151,18 @@
       end
     end
 
+    context 'when a user-agent header is specified as a client option as lower-case' do
+
+      let(:client) do
+        described_class.new(transport_class: Elasticsearch::Transport::Transport::HTTP::Curb,
+                            transport_options: { headers: { 'user-agent' => 'testing' } })
+      end
+
+      it 'sets the specified User-Agent header' do
+        expect(client.transport.connections.first.connection.headers['User-Agent']).to eq('testing')
+      end
+    end
+
     context 'when a Content-Type header is specified as client option' do
 
       let(:client) do