Set content type header when payload is provided

Author: aziemski

http/headers/headers.go

@@ -0,0 +1,7 @@
+package headers
+
+// HTTP headers
+const (
+	ContentType = "Content-Type"
+	Accept      = "Accept"
+)

http/mediatypes/mediatypes.go

@@ -0,0 +1,7 @@
+package mediatypes
+
+// Media types
+const (
+	ApplicationJSON     = "application/json"
+	ApplicationJSONUtf8 = "application/json; charset=utf-8"
+)

remote.go

@@ -19,6 +19,8 @@ import (
 
 	"github.com/blang/semver"
 	"github.com/tebeka/selenium/firefox"
+	"github.com/tebeka/selenium/http/headers"
+	"github.com/tebeka/selenium/http/mediatypes"
 	"github.com/tebeka/selenium/log"
 )
 
@@ -59,15 +61,15 @@ type remoteWD struct {
 // server.
 var HTTPClient = http.DefaultClient
 
-// jsonContentType is JSON content type.
-const jsonContentType = "application/json"
-
 func newRequest(method string, url string, data []byte) (*http.Request, error) {
 	request, err := http.NewRequest(method, url, bytes.NewBuffer(data))
 	if err != nil {
 		return nil, err
 	}
-	request.Header.Add("Accept", jsonContentType)
+	if data != nil {
+		request.Header.Add(headers.ContentType, mediatypes.ApplicationJSONUtf8)
+	}
+	request.Header.Add(headers.Accept, mediatypes.ApplicationJSON)
 
 	return request, nil
 }
@@ -148,19 +150,19 @@ func executeCommand(method, url string, data []byte) (json.RawMessage, error) {
 				buf = prettyBuf.Bytes()
 			}
 		}
-		debugLog("<- %s [%s]\n%s", response.Status, response.Header["Content-Type"], buf)
+		debugLog("<- %s [%s]\n%s", response.Status, response.Header[headers.ContentType], buf)
 	}
 	if err != nil {
 		return nil, errors.New(response.Status)
 	}
 
-	fullCType := response.Header.Get("Content-Type")
+	fullCType := response.Header.Get(headers.ContentType)
 	cType, _, err := mime.ParseMediaType(fullCType)
 	if err != nil {
-		return nil, fmt.Errorf("got content type header %q, expected %q", fullCType, jsonContentType)
+		return nil, fmt.Errorf("got content type header %q, expected %q", fullCType, mediatypes.ApplicationJSON)
 	}
-	if cType != jsonContentType {
-		return nil, fmt.Errorf("got content type %q, expected %q", cType, jsonContentType)
+	if cType != mediatypes.ApplicationJSON {
+		return nil, fmt.Errorf("got content type %q, expected %q", cType, mediatypes.ApplicationJSON)
 	}
 
 	reply := new(serverReply)