Oops. Tests.

middleware/gzip/gzip_test.go

@@ -80,7 +80,6 @@ func TestGzipHandler(t *testing.T) {
 
 func nextFunc(shouldGzip bool) middleware.Handler {
 	return middleware.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
-		w.WriteHeader(200)
 		w.Write([]byte("test"))
 		if shouldGzip {
 			if r.Header.Get("Accept-Encoding") != "" {

middleware/gzip/response_filter.go

@@ -29,8 +29,9 @@ func (l LengthFilter) ShouldCompress(w http.ResponseWriter) bool {
 // gzip compressed data if ResponseFilters are satisfied or
 // uncompressed data otherwise.
 type ResponseFilterWriter struct {
-	filters        []ResponseFilter
-	shouldCompress bool
+	filters           []ResponseFilter
+	shouldCompress    bool
+	statusCodeWritten bool
 	*gzipResponseWriter
 }
 
@@ -39,7 +40,7 @@ func NewResponseFilterWriter(filters []ResponseFilter, gz *gzipResponseWriter) *
 	return &ResponseFilterWriter{filters: filters, gzipResponseWriter: gz}
 }
 
-// Write wraps underlying Write method and compresses if filters
+// Write wraps underlying WriteHeader method and compresses if filters
 // are satisfied.
 func (r *ResponseFilterWriter) WriteHeader(code int) {
 	// Determine if compression should be used or not.
@@ -62,11 +63,15 @@ func (r *ResponseFilterWriter) WriteHeader(code int) {
 	} else {
 		r.ResponseWriter.WriteHeader(code)
 	}
+	r.statusCodeWritten = true
 }
 
 // Write wraps underlying Write method and compresses if filters
 // are satisfied
 func (r *ResponseFilterWriter) Write(b []byte) (int, error) {
+	if !r.statusCodeWritten {
+		r.WriteHeader(http.StatusOK)
+	}
 	if r.shouldCompress {
 		return r.gzipResponseWriter.Write(b)
 	}

middleware/gzip/response_filter_test.go

@@ -63,7 +63,6 @@ func TestResponseFilterWriter(t *testing.T) {
 	for i, ts := range tests {
 		server.Next = middleware.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
 			w.Header().Set("Content-Length", fmt.Sprint(len(ts.body)))
-			w.WriteHeader(200)
 			w.Write([]byte(ts.body))
 			return 200, nil
 		})