add very simple http/2 test

src/test.rs

@@ -146,6 +146,11 @@ impl TestServer {
         tcp.local_addr().unwrap()
     }
 
+    /// Construct test server url
+    pub fn addr(&self) -> net::SocketAddr {
+        self.addr
+    }
+
     /// Construct test server url
     pub fn url(&self, uri: &str) -> String {
         if uri.starts_with('/') {