reduce dependency tree by features

src/test/body_send.rs

@@ -27,6 +27,7 @@ fn user_set_content_length_on_str() {
 }
 
 #[test]
+#[cfg(feature = "json")]
 fn content_length_on_json() {
     test::set_handler("/content_length_on_json", |_req, _url| {
         test::make_response(200, "OK", vec![], vec![])
@@ -57,6 +58,7 @@ fn content_length_and_chunked() {
 }
 
 #[test]
+#[cfg(feature = "charset")]
 fn str_with_encoding() {
     test::set_handler("/str_with_encoding", |_req, _url| {
         test::make_response(200, "OK", vec![], vec![])

src/test/simple.rs

@@ -59,6 +59,7 @@ fn body_as_text() {
 }
 
 #[test]
+#[cfg(feature = "json")]
 fn body_as_json() {
     test::set_handler("/body_as_json", |_req, _url| {
         test::make_response(