fix(http1): code review fixes

- remove uncessary if statement
- prefer into_iter() instead of drain()
- prefer !vec.is_empty() to vec.len() > 0
- add another test for multiple trailer headers in single response

src/proto/h1/conn.rs

@@ -265,17 +265,12 @@ where
             self.state.reading = Reading::Body(Decoder::new(msg.decode));
         }
 
-        if msg
+        self.state.allow_trailer_fields = msg
             .head
             .headers
             .get(TE)
             .map(|te_header| te_header == "trailers")
-            .unwrap_or(false)
-        {
-            self.state.allow_trailer_fields = true;
-        } else {
-            self.state.allow_trailer_fields = false;
-        }
+            .unwrap_or(false);
 
         Poll::Ready(Some(Ok((msg.head, msg.decode, wants))))
     }

src/proto/h1/encode.rs

@@ -165,7 +165,7 @@ impl Encoder {
 
     pub(crate) fn encode_trailers<B>(
         &self,
-        mut trailers: HeaderMap,
+        trailers: HeaderMap,
         title_case_headers: bool,
     ) -> Option<EncodedBuf<B>> {
         match &self.kind {
@@ -175,7 +175,7 @@ impl Encoder {
                 let mut cur_name = None;
                 let mut allowed_trailers = HeaderMap::new();
 
-                for (opt_name, value) in trailers.drain() {
+                for (opt_name, value) in trailers.into_iter() {
                     if let Some(n) = opt_name {
                         cur_name = Some(n);
                     }
@@ -530,14 +530,18 @@ mod tests {
         let trailers = vec![HeaderValue::from_static("chunky-trailer")];
         let encoder = encoder.into_chunked_with_trailing_fields(trailers);
 
-        let mut headers = HeaderMap::new();
-        headers.insert(
-            HeaderName::from_static("chunky-trailer"),
-            HeaderValue::from_static("header data"),
-        );
-        headers.insert(
-            HeaderName::from_static("should-not-be-included"),
-            HeaderValue::from_static("oops"),
+        let headers = HeaderMap::from_iter(
+            vec![
+                (
+                    HeaderName::from_static("chunky-trailer"),
+                    HeaderValue::from_static("header data"),
+                ),
+                (
+                    HeaderName::from_static("should-not-be-included"),
+                    HeaderValue::from_static("oops"),
+                ),
+            ]
+            .into_iter(),
         );
 
         let buf1 = encoder.encode_trailers::<&[u8]>(headers, false).unwrap();
@@ -547,6 +551,39 @@ mod tests {
         assert_eq!(dst, b"0\r\nchunky-trailer: header data\r\n\r\n");
     }
 
+    #[test]
+    fn chunked_with_multiple_trailer_headers() {
+        let encoder = Encoder::chunked();
+        let trailers = vec![
+            HeaderValue::from_static("chunky-trailer"),
+            HeaderValue::from_static("chunky-trailer-2"),
+        ];
+        let encoder = encoder.into_chunked_with_trailing_fields(trailers);
+
+        let headers = HeaderMap::from_iter(
+            vec![
+                (
+                    HeaderName::from_static("chunky-trailer"),
+                    HeaderValue::from_static("header data"),
+                ),
+                (
+                    HeaderName::from_static("chunky-trailer-2"),
+                    HeaderValue::from_static("more header data"),
+                ),
+            ]
+            .into_iter(),
+        );
+
+        let buf1 = encoder.encode_trailers::<&[u8]>(headers, false).unwrap();
+
+        let mut dst = Vec::new();
+        dst.put(buf1);
+        assert_eq!(
+            dst,
+            b"0\r\nchunky-trailer: header data\r\nchunky-trailer-2: more header data\r\n\r\n"
+        );
+    }
+
     #[test]
     fn chunked_with_no_trailer_header() {
         let encoder = Encoder::chunked();

src/proto/h1/role.rs

@@ -1350,7 +1350,7 @@ impl Client {
                 let allowed_trailer_fields: Vec<HeaderValue> =
                     headers.get_all(header::TRAILER).iter().cloned().collect();
 
-                if allowed_trailer_fields.len() > 0 {
+                if !allowed_trailer_fields.is_empty() {
                     return enc.into_chunked_with_trailing_fields(allowed_trailer_fields);
                 }
             }