add unit tests

client/tests/scripts/test_websocket.js

@@ -0,0 +1,24 @@
+function test() {
+  let message_len = 128*1024;
+
+  return new Promise((resolve, reject) => {
+    let ws = new libcurl.WebSocket("wss://echo.websocket.org");
+    ws.addEventListener("open", () => {
+      ws.send("hello".repeat(message_len));
+    });
+    
+    let messages = 0;
+    ws.addEventListener("message", (event) => {
+      messages += 1;
+      if (messages >= 2) {
+        if (event.data !== "hello".repeat(message_len)) reject("unexpected response");
+        if (messages >= 11) resolve();
+        ws.send("hello".repeat(message_len));
+      }
+    });
+
+    ws.addEventListener("error", () => {
+      reject("ws error occurred");
+    });
+  })
+}