gzip: Fix tests

middleware/gzip/filter_test.go

@@ -108,7 +108,7 @@ func TestMIMEFilter(t *testing.T) {
 	}
 	for i, m := range mimes {
 		r := urlRequest("file" + m)
-		r.Header.Set("Content-Type", m)
+		r.Header.Set("Accept", m)
 		if !filter.ShouldCompress(r) {
 			t.Errorf("Test %v: Should be valid filter", i)
 		}

middleware/gzip/gzip_test.go

@@ -89,7 +89,7 @@ func TestGzipHandler(t *testing.T) {
 		if err != nil {
 			t.Error(err)
 		}
-		r.Header.Set("Content-Type", m)
+		r.Header.Set("Accept", m)
 		r.Header.Set("Accept-Encoding", "gzip")
 		_, err = gz.ServeHTTP(w, r)
 		if err != nil {