Surface driver connection object when using a proxied dialect

Improve the interface used by adapted drivers, like the asyncio ones,
to access the actual connection object returned by the driver.

The :class:`_engine._ConnectionRecord` and
:class:`_engine._ConnectionFairy` now have two new attributes:

* ``dbapi_connection`` always represents a DBAPI compatible
object.  For pep-249 drivers, this is the DBAPI connection as it always
has been, previously accessed under the ``.connection`` attribute.
For asyncio drivers that SQLAlchemy adapts into a pep-249 interface,
the returned object will normally be a SQLAlchemy adaption object
called :class:`_engine.AdaptedConnection`.
* ``driver_connection`` always represents the actual connection object
maintained by the third party pep-249 DBAPI or async driver in use.
For standard pep-249 DBAPIs, this will always be the same object
as that of the ``dbapi_connection``.  For an asyncio driver, it will be
the underlying asyncio-only connection object.

The ``.connection`` attribute remains available and is now a legacy alias
of ``.dbapi_connection``.

Fixes: #6832
Change-Id: Ib72f97deefca96dce4e61e7c38ba430068d6a82e

1 files changed, 40 insertions, 5 deletions

diff --git a/lib/sqlalchemy/testing/plugin/pytestplugin.py b/lib/sqlalchemy/testing/plugin/pytestplugin.py
index 4e82f10c1..d28048f70 100644
--- a/lib/sqlalchemy/testing/plugin/pytestplugin.py
+++ b/lib/sqlalchemy/testing/plugin/pytestplugin.py
@@ -358,6 +358,7 @@ _current_class = None
 
 def pytest_runtest_setup(item):
     from sqlalchemy.testing import asyncio
+    from sqlalchemy.util import string_types
 
     if not isinstance(item, pytest.Function):
         return
@@ -378,13 +379,38 @@ def pytest_runtest_setup(item):
         _current_class = item.parent.parent
 
         def finalize():
-            global _current_class
+            global _current_class, _current_report
             _current_class = None
 
-            asyncio._maybe_async_provisioning(
-                plugin_base.stop_test_class_outside_fixtures,
-                item.parent.parent.cls,
-            )
+            try:
+                asyncio._maybe_async_provisioning(
+                    plugin_base.stop_test_class_outside_fixtures,
+                    item.parent.parent.cls,
+                )
+            except Exception as e:
+                # in case of an exception during teardown attach the original
+                # error to the exception message, otherwise it will get lost
+                if _current_report.failed:
+                    if not e.args:
+                        e.args = (
+                            "__Original test failure__:\n"
+                            + _current_report.longreprtext,
+                        )
+                    elif e.args[-1] and isinstance(e.args[-1], string_types):
+                        args = list(e.args)
+                        args[-1] += (
+                            "\n__Original test failure__:\n"
+                            + _current_report.longreprtext
+                        )
+                        e.args = tuple(args)
+                    else:
+                        e.args += (
+                            "__Original test failure__",
+                            _current_report.longreprtext,
+                        )
+                raise
+            finally:
+                _current_report = None
 
         item.parent.parent.addfinalizer(finalize)
 
@@ -404,6 +430,15 @@ def pytest_runtest_call(item):
     )
 
 
+_current_report = None
+
+
+def pytest_runtest_logreport(report):
+    global _current_report
+    if report.when == "call":
+        _current_report = report
+
+
 def pytest_runtest_teardown(item, nextitem):
     # runs inside of pytest function fixture scope
     # after test function runs