Detect non async driver on engine creation

An error is raised when creating an async engine with an
incompatible dbapi. Before the error was raised only when
first using the engine.

Change-Id: I977952b4c03ae51f568749ad744c545197bcd887
Reference: #5920

diff --git a/lib/sqlalchemy/exc.py b/lib/sqlalchemy/exc.py
index 289b8dfab1c4313b6a6a63c1f64f40b722961bd7..a0a86826d17d182c33f1ca6b7989612dcebd4ba0 100644 (file)
--- a/lib/sqlalchemy/exc.py
+++ b/lib/sqlalchemy/exc.py
@@ -287,7 +287,7 @@ class NoReferenceError(InvalidRequestError):
 
 class AwaitRequired(InvalidRequestError):
     """Error raised by the async greenlet spawn if no async operation
-    was awaited when it required one
+    was awaited when it required one.
 
     """
 

diff --git a/lib/sqlalchemy/ext/asyncio/engine.py b/lib/sqlalchemy/ext/asyncio/engine.py
index aa7e60dfb5526d7814f084bb959330e20723c7dd..db95ab371260f9c94d8d14e045be31a6da97ce8d 100644 (file)
--- a/lib/sqlalchemy/ext/asyncio/engine.py
+++ b/lib/sqlalchemy/ext/asyncio/engine.py
@@ -527,6 +527,11 @@ class AsyncEngine(ProxyComparable, AsyncConnectable):
             await self.conn.close()
 
     def __init__(self, sync_engine: Engine):
+        if not sync_engine.dialect.is_async:
+            raise exc.InvalidRequestError(
+                "The asyncio extension requires an async driver to be used. "
+                f"The loaded {sync_engine.dialect.driver!r} is not async."
+            )
         self.sync_engine = self._proxied = sync_engine
 
     def begin(self):

diff --git a/test/ext/asyncio/test_engine_py3k.py b/test/ext/asyncio/test_engine_py3k.py
index 72d86688219df1d75fb423f7b6288c956a9b7f0b..512f0447f8081baed5f4cb1d0c9169659a90c3f4 100644 (file)
--- a/test/ext/asyncio/test_engine_py3k.py
+++ b/test/ext/asyncio/test_engine_py3k.py
@@ -1,6 +1,7 @@
 import asyncio
 
 from sqlalchemy import Column
+from sqlalchemy import create_engine
 from sqlalchemy import delete
 from sqlalchemy import event
 from sqlalchemy import exc
@@ -662,9 +663,18 @@ class AsyncResultTest(EngineFixture):
 
 
 class TextSyncDBAPI(fixtures.TestBase):
+    def test_sync_dbapi_raises(self):
+        with expect_raises_message(
+            exc.InvalidRequestError,
+            "The asyncio extension requires an async driver to be used.",
+        ):
+            create_async_engine("sqlite:///:memory:")
+
     @testing.fixture
     def async_engine(self):
-        return create_async_engine("sqlite:///:memory:")
+        engine = create_engine("sqlite:///:memory:", future=True)
+        engine.dialect.is_async = True
+        return _async_engine.AsyncEngine(engine)
 
     @async_test
     @combinations(