1 files changed, 52 insertions, 0 deletions
diff --git a/dom/webgpu/tests/cts/checkout/src/common/internal/websocket_logger.ts b/dom/webgpu/tests/cts/checkout/src/common/internal/websocket_logger.ts
new file mode 100644
index 0000000000..30246df843
--- /dev/null
+++ b/dom/webgpu/tests/cts/checkout/src/common/internal/websocket_logger.ts
@@ -0,0 +1,52 @@
+/**
+ * - 'uninitialized' means we haven't tried to connect yet
+ * - Promise means it's pending
+ * - 'failed' means it failed (this is the most common case, where the logger isn't running)
+ * - WebSocket means it succeeded
+ */
+let connection: Promise<WebSocket | 'failed'> | WebSocket | 'failed' | 'uninitialized' =
+  'uninitialized';
+
+/**
+ * Log a string to a websocket at `localhost:59497`. See `tools/websocket-logger`.
+ *
+ * This does nothing if a connection couldn't be established on the first call.
+ */
+export function logToWebsocket(msg: string) {
+  if (connection === 'failed') {
+    return;
+  }
+
+  if (connection === 'uninitialized') {
+    connection = new Promise(resolve => {
+      if (typeof WebSocket === 'undefined') {
+        resolve('failed');
+        return;
+      }
+
+      const ws = new WebSocket('ws://localhost:59497/optional_cts_websocket_logger');
+      ws.onopen = () => {
+        resolve(ws);
+      };
+      ws.onerror = () => {
+        connection = 'failed';
+        resolve('failed');
+      };
+      ws.onclose = () => {
+        connection = 'failed';
+        resolve('failed');
+      };
+    });
+    void connection.then(resolved => {
+      connection = resolved;
+    });
+  }
+
+  void (async () => {
+    // connection may be a promise or a value here. Either is OK to await.
+    const ws = await connection;
+    if (ws !== 'failed') {
+      ws.send(msg);
+    }
+  })();
+}