chore: Guard that import ldclient does not require aiohttp

ldclient/testing/test_aio.py

@@ -6,6 +6,8 @@
 """
 
 import asyncio
+import subprocess
+import sys
 import threading
 import time
 
@@ -522,3 +524,23 @@ def test_sse_factory_proxy_precedence(self):
         assert AsyncSSEFactory(cfg)._proxy == 'http://cfg-proxy:9000'
         # Neither set -> None (per-URL env fallback happens in create()).
         assert AsyncSSEFactory(Config('sdk-key'))._proxy is None
+
+
+class TestImportSafety:
+    def test_import_ldclient_does_not_require_aiohttp(self):
+        """A bare ``import ldclient`` must not import anything that requires an
+        optional dependency. aiohttp (the ``async`` extra) is optional, so a
+        sync-only install must still be able to import ldclient.
+        """
+        code = "import ldclient, sys; sys.exit(1 if 'aiohttp' in sys.modules else 0)"
+        result = subprocess.run(
+            [sys.executable, "-c", code],
+            capture_output=True,
+            text=True,
+        )
+
+        assert result.returncode == 0, (
+            "importing ldclient pulled in aiohttp. Keep aiohttp off the eager "
+            "import path (import async_client / transport lazily).\n"
+            "stderr:\n%s" % result.stderr
+        )