from sqlalchemy.testing import eq_, ne_, assert_raises, \
    expect_warnings, assert_raises_message
import time
from sqlalchemy import (
    select, MetaData, Integer, String, create_engine, pool, exc, util)
from sqlalchemy.testing.schema import Table, Column
import sqlalchemy as tsa
from sqlalchemy.engine import url
from sqlalchemy import testing
from sqlalchemy.testing import mock
from sqlalchemy.testing import engines
from sqlalchemy.testing import fixtures
from sqlalchemy.testing.engines import testing_engine
from sqlalchemy.testing.mock import Mock, call, patch
from sqlalchemy import event
from sqlalchemy.testing.util import gc_collect


class MockError(Exception):
    pass


class MockDisconnect(MockError):
    pass


class MockExitIsh(BaseException):
    pass


def mock_connection():
    def mock_cursor():
        def execute(*args, **kwargs):
            if conn.explode == 'execute':
                raise MockDisconnect("Lost the DB connection on execute")
            elif conn.explode == 'interrupt':
                conn.explode = "explode_no_disconnect"
                raise MockExitIsh("Keyboard / greenlet / etc interruption")
            elif conn.explode == 'interrupt_dont_break':
                conn.explode = None
                raise MockExitIsh("Keyboard / greenlet / etc interruption")
            elif conn.explode in ('execute_no_disconnect',
                                  'explode_no_disconnect'):
                raise MockError(
                    "something broke on execute but we didn't lose the "
                    "connection")
            elif conn.explode in ('rollback', 'rollback_no_disconnect',
                                  'explode_no_disconnect'):
                raise MockError(
                    "something broke on execute but we didn't lose the "
                    "connection")
            elif args and "SELECT" in args[0]:
                cursor.description = [('foo', None, None, None, None, None)]
            else:
                return

        def close():
            cursor.fetchall = cursor.fetchone = \
                Mock(side_effect=MockError("cursor closed"))
        cursor = Mock(
            execute=Mock(side_effect=execute),
            close=Mock(side_effect=close))
        return cursor

    def cursor():
        while True:
            yield mock_cursor()

    def rollback():
        if conn.explode == 'rollback':
            raise MockDisconnect("Lost the DB connection on rollback")
        if conn.explode == 'rollback_no_disconnect':
            raise MockError(
                "something broke on rollback but we didn't lose the "
                "connection")
        else:
            return

    conn = Mock(
        rollback=Mock(side_effect=rollback),
        cursor=Mock(side_effect=cursor()))
    return conn


def MockDBAPI():
    connections = []
    stopped = [False]

    def connect():
        while True:
            if stopped[0]:
                raise MockDisconnect("database is stopped")
            conn = mock_connection()
            connections.append(conn)
            yield conn

    def shutdown(explode='execute', stop=False):
        stopped[0] = stop
        for c in connections:
            c.explode = explode

    def restart():
        stopped[0] = False
        connections[:] = []

    def dispose():
        stopped[0] = False
        for c in connections:
            c.explode = None
        connections[:] = []

    return Mock(
        connect=Mock(side_effect=connect()),
        shutdown=Mock(side_effect=shutdown),
        dispose=Mock(side_effect=dispose),
        restart=Mock(side_effect=restart),
        paramstyle='named',
        connections=connections,
        Error=MockError)


class PrePingMockTest(fixtures.TestBase):
    def setup(self):
        self.dbapi = MockDBAPI()

    def _pool_fixture(self, pre_ping):
        dialect = url.make_url(
            'postgresql://foo:bar@localhost/test').get_dialect()()
        dialect.dbapi = self.dbapi
        _pool = pool.QueuePool(
            creator=lambda: self.dbapi.connect('foo.db'), pre_ping=pre_ping,
            dialect=dialect)

        dialect.is_disconnect = \
            lambda e, conn, cursor: isinstance(e, MockDisconnect)
        return _pool

    def teardown(self):
        self.dbapi.dispose()

    def test_connect_across_restart(self):
        pool = self._pool_fixture(pre_ping=True)

        conn = pool.connect()
        stale_connection = conn.connection
        conn.close()

        self.dbapi.shutdown("execute")
        self.dbapi.restart()

        conn = pool.connect()
        cursor = conn.cursor()
        cursor.execute("hi")

        stale_cursor = stale_connection.cursor()
        assert_raises(
            MockDisconnect,
            stale_cursor.execute, "hi"
        )

    def test_raise_db_is_stopped(self):
        pool = self._pool_fixture(pre_ping=True)

        conn = pool.connect()
        conn.close()

        self.dbapi.shutdown("execute", stop=True)

        assert_raises_message(
            MockDisconnect,
            "database is stopped",
            pool.connect
        )

    def test_waits_til_exec_wo_ping_db_is_stopped(self):
        pool = self._pool_fixture(pre_ping=False)

        conn = pool.connect()
        conn.close()

        self.dbapi.shutdown("execute", stop=True)

        conn = pool.connect()

        cursor = conn.cursor()
        assert_raises_message(
            MockDisconnect,
            "Lost the DB connection on execute",
            cursor.execute, "foo"
        )

    def test_waits_til_exec_wo_ping_db_is_restarted(self):
        pool = self._pool_fixture(pre_ping=False)

        conn = pool.connect()
        conn.close()

        self.dbapi.shutdown("execute", stop=True)
        self.dbapi.restart()

        conn = pool.connect()

        cursor = conn.cursor()
        assert_raises_message(
            MockDisconnect,
            "Lost the DB connection on execute",
            cursor.execute, "foo"
        )

    @testing.requires.predictable_gc
    def test_pre_ping_weakref_finalizer(self):
        pool = self._pool_fixture(pre_ping=True)

        conn = pool.connect()
        old_dbapi_conn = conn.connection
        conn.close()

        eq_(old_dbapi_conn.mock_calls, [call.cursor(), call.rollback()])

        self.dbapi.shutdown("execute", stop=True)
        self.dbapi.restart()

        conn = pool.connect()
        dbapi_conn = conn.connection
        del conn
        gc_collect()

        # new connection was reset on return appropriately
        eq_(dbapi_conn.mock_calls, [call.cursor(), call.rollback()])

        # old connection was just closed - did not get an
        # erroneous reset on return
        eq_(
            old_dbapi_conn.mock_calls,
            [call.cursor(), call.rollback(), call.cursor(), call.close()]
        )


class MockReconnectTest(fixtures.TestBase):
    def setup(self):
        self.dbapi = MockDBAPI()

        self.db = testing_engine(
            'postgresql://foo:bar@localhost/test',
            options=dict(module=self.dbapi, _initialize=False))

        self.mock_connect = call(
            host='localhost', password='bar', user='foo', database='test')
        # monkeypatch disconnect checker
        self.db.dialect.is_disconnect = \
            lambda e, conn, cursor: isinstance(e, MockDisconnect)

    def teardown(self):
        self.dbapi.dispose()

    def test_reconnect(self):
        """test that an 'is_disconnect' condition will invalidate the
        connection, and additionally dispose the previous connection
        pool and recreate."""

        db_pool = self.db.pool

        # make a connection

        conn = self.db.connect()

        # connection works

        conn.execute(select([1]))

        # create a second connection within the pool, which we'll ensure
        # also goes away

        conn2 = self.db.connect()
        conn2.close()

        # two connections opened total now

        assert len(self.dbapi.connections) == 2

        # set it to fail

        self.dbapi.shutdown()
        assert_raises(
            tsa.exc.DBAPIError,
            conn.execute, select([1])
        )

        # assert was invalidated

        assert not conn.closed
        assert conn.invalidated

        # close shouldn't break

        conn.close()

        # ensure one connection closed...
        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()], []]
        )

        conn = self.db.connect()

        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()], [call()], []]
        )

        conn.execute(select([1]))
        conn.close()

        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()], [call()], []]
        )

    def test_invalidate_trans(self):
        conn = self.db.connect()
        trans = conn.begin()
        self.dbapi.shutdown()

        assert_raises(
            tsa.exc.DBAPIError,
            conn.execute, select([1])
        )

        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()]]
        )
        assert not conn.closed
        assert conn.invalidated
        assert trans.is_active
        assert_raises_message(
            tsa.exc.StatementError,
            "Can't reconnect until invalid transaction is rolled back",
            conn.execute, select([1])
        )
        assert trans.is_active

        assert_raises_message(
            tsa.exc.InvalidRequestError,
            "Can't reconnect until invalid transaction is rolled back",
            trans.commit)

        assert trans.is_active
        trans.rollback()
        assert not trans.is_active
        conn.execute(select([1]))
        assert not conn.invalidated
        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()], []]
        )

    def test_invalidate_dont_call_finalizer(self):
        conn = self.db.connect()
        finalizer = mock.Mock()
        conn.connection._connection_record.\
            finalize_callback.append(finalizer)
        conn.invalidate()
        assert conn.invalidated
        eq_(finalizer.call_count, 0)

    def test_conn_reusable(self):
        conn = self.db.connect()

        conn.execute(select([1]))

        eq_(
            self.dbapi.connect.mock_calls,
            [self.mock_connect]
        )

        self.dbapi.shutdown()

        assert_raises(
            tsa.exc.DBAPIError,
            conn.execute, select([1])
        )

        assert not conn.closed
        assert conn.invalidated

        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()]]
        )

        # test reconnects
        conn.execute(select([1]))
        assert not conn.invalidated

        eq_(
            [c.close.mock_calls for c in self.dbapi.connections],
            [[call()], []]
        )

    def test_invalidated_close(self):
        conn = self.db.connect()

        self.dbapi.shutdown()

        assert_raises(
            tsa.exc.DBAPIError,
            conn.execute, select([1])
        )

        conn.close()
        assert conn.closed
        assert conn.invalidated
        assert_raises_message(
            tsa.exc.StatementError,
            "This Connection is closed",
            conn.execute, select([1])
        )

    def test_noreconnect_execute_plus_closewresult(self):
        conn = self.db.connect(close_with_result=True)

        self.dbapi.shutdown("execute_no_disconnect")

        # raises error
        assert_raises_message(
            tsa.exc.DBAPIError,
            "something broke on execute but we didn't lose the connection",
            conn.execute, select([1])
        )

        assert conn.closed
        assert not conn.invalidated

    def test_noreconnect_rollback_plus_closewresult(self):
        conn = self.db.connect(close_with_result=True)

        self.dbapi.shutdown("rollback_no_disconnect")

        # raises error
        with expect_warnings(
            "An exception has occurred during handling .*"
            "something broke on execute but we didn't lose the connection",
            py2konly=True
        ):
            assert_raises_message(
                tsa.exc.DBAPIError,
                "something broke on rollback but we didn't "
                "lose the connection",
                conn.execute, select([1])
            )

        assert conn.closed
        assert not conn.invalidated

        assert_raises_message(
            tsa.exc.StatementError,
            "This Connection is closed",
            conn.execute, select([1])
        )

    def test_reconnect_on_reentrant(self):
        conn = self.db.connect()

        conn.execute(select([1]))

        assert len(self.dbapi.connections) == 1

        self.dbapi.shutdown("rollback")

        # raises error
        with expect_warnings(
            "An exception has occurred during handling .*"
            "something broke on execute but we didn't lose the connection",
            py2konly=True
        ):
            assert_raises_message(
                tsa.exc.DBAPIError,
                "Lost the DB connection on rollback",
                conn.execute, select([1])
            )

        assert not conn.closed
        assert conn.invalidated

    def test_reconnect_on_reentrant_plus_closewresult(self):
        conn = self.db.connect(close_with_result=True)

        self.dbapi.shutdown("rollback")

        # raises error
        with expect_warnings(
            "An exception has occurred during handling .*"
            "something broke on execute but we didn't lose the connection",
            py2konly=True
        ):
            assert_raises_message(
                tsa.exc.DBAPIError,
                "Lost the DB connection on rollback",
                conn.execute, select([1])
            )

        assert conn.closed
        assert conn.invalidated

        assert_raises_message(
            tsa.exc.StatementError,
            "This Connection is closed",
            conn.execute, select([1])
        )

    def test_check_disconnect_no_cursor(self):
        conn = self.db.connect()
        result = conn.execute(select([1]))
        result.cursor.close()
        conn.close()

        assert_raises_message(
            tsa.exc.DBAPIError,
            "cursor closed",
            list, result
        )

    def test_dialect_initialize_once(self):
        from sqlalchemy.engine.url import URL
        from sqlalchemy.engine.default import DefaultDialect
        dbapi = self.dbapi

        mock_dialect = Mock()

        class MyURL(URL):
            def _get_entrypoint(self):
                return Dialect

            def get_dialect(self):
                return Dialect

        class Dialect(DefaultDialect):
            initialize = Mock()

        engine = create_engine(MyURL("foo://"), module=dbapi)
        c1 = engine.connect()
        engine.dispose()
        c2 = engine.connect()
        eq_(Dialect.initialize.call_count, 1)

    def test_invalidate_conn_w_contextmanager_interrupt(self):
        # test [ticket:3803]
        pool = self.db.pool

        conn = self.db.connect()
        self.dbapi.shutdown("interrupt")

        def go():
            with conn.begin():
                conn.execute(select([1]))

        assert_raises(
            MockExitIsh,
            go
        )

        assert conn.invalidated

        eq_(pool._invalidate_time, 0)  # pool not invalidated

        conn.execute(select([1]))
        assert not conn.invalidated

    def test_invalidate_conn_interrupt_nodisconnect_workaround(self):
        # test [ticket:3803] workaround for no disconnect on keyboard interrupt

        @event.listens_for(self.db, "handle_error")
        def cancel_disconnect(ctx):
            ctx.is_disconnect = False

        pool = self.db.pool

        conn = self.db.connect()
        self.dbapi.shutdown("interrupt_dont_break")

        def go():
            with conn.begin():
                conn.execute(select([1]))

        assert_raises(
            MockExitIsh,
            go
        )

        assert not conn.invalidated

        eq_(pool._invalidate_time, 0)  # pool not invalidated

        conn.execute(select([1]))
        assert not conn.invalidated

    def test_invalidate_conn_w_contextmanager_disconnect(self):
        # test [ticket:3803] change maintains old behavior

        pool = self.db.pool

        conn = self.db.connect()
        self.dbapi.shutdown("execute")

        def go():
            with conn.begin():
                conn.execute(select([1]))

        assert_raises(
            exc.DBAPIError,  # wraps a MockDisconnect
            go
        )

        assert conn.invalidated

        ne_(pool._invalidate_time, 0)  # pool is invalidated

        conn.execute(select([1]))
        assert not conn.invalidated

class CursorErrTest(fixtures.TestBase):
    # this isn't really a "reconnect" test, it's more of
    # a generic "recovery".   maybe this test suite should have been
    # named "test_error_recovery".
    def _fixture(self, explode_on_exec, initialize):
        class DBAPIError(Exception):
            pass

        def MockDBAPI():
            def cursor():
                while True:
                    if explode_on_exec:
                        yield Mock(
                            description=[],
                            close=Mock(side_effect=DBAPIError("explode")),
                            execute=Mock(side_effect=DBAPIError("explode"))
                        )
                    else:
                        yield Mock(
                            description=[],
                            close=Mock(side_effect=Exception("explode")),
                        )

            def connect():
                while True:
                    yield Mock(
                        spec=['cursor', 'commit', 'rollback', 'close'],
                        cursor=Mock(side_effect=cursor()),)

            return Mock(
                Error=DBAPIError, paramstyle='qmark',
                connect=Mock(side_effect=connect()))
        dbapi = MockDBAPI()

        from sqlalchemy.engine import default
        url = Mock(
            get_dialect=lambda: default.DefaultDialect,
            _get_entrypoint=lambda: default.DefaultDialect,
            _instantiate_plugins=lambda kwargs: (),
            translate_connect_args=lambda: {}, query={},)
        eng = testing_engine(
            url, options=dict(module=dbapi, _initialize=initialize))
        eng.pool.logger = Mock()
        return eng

    def test_cursor_explode(self):
        db = self._fixture(False, False)
        conn = db.connect()
        result = conn.execute("select foo")
        result.close()
        conn.close()
        eq_(
            db.pool.logger.error.mock_calls,
            [call('Error closing cursor', exc_info=True)]
        )

    def test_cursor_shutdown_in_initialize(self):
        db = self._fixture(True, True)
        assert_raises_message(
            exc.SAWarning,
            "Exception attempting to detect",
            db.connect
        )
        eq_(
            db.pool.logger.error.mock_calls,
            [call('Error closing cursor', exc_info=True)]
        )


def _assert_invalidated(fn, *args):
    try:
        fn(*args)
        assert False
    except tsa.exc.DBAPIError as e:
        if not e.connection_invalidated:
            raise


class RealReconnectTest(fixtures.TestBase):
    __backend__ = True
    __requires__ = 'graceful_disconnects', 'ad_hoc_engines'

    def setup(self):
        self.engine = engines.reconnecting_engine()

    def teardown(self):
        self.engine.dispose()

    def test_reconnect(self):
        conn = self.engine.connect()

        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.closed

        self.engine.test_shutdown()

        _assert_invalidated(conn.execute, select([1]))

        assert not conn.closed
        assert conn.invalidated

        assert conn.invalidated
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.invalidated

        # one more time
        self.engine.test_shutdown()
        _assert_invalidated(conn.execute, select([1]))

        assert conn.invalidated
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.invalidated

        conn.close()

    def test_multiple_invalidate(self):
        c1 = self.engine.connect()
        c2 = self.engine.connect()

        eq_(c1.execute(select([1])).scalar(), 1)

        p1 = self.engine.pool
        self.engine.test_shutdown()

        _assert_invalidated(c1.execute, select([1]))

        p2 = self.engine.pool

        _assert_invalidated(c2.execute, select([1]))

        # pool isn't replaced
        assert self.engine.pool is p2

    def test_branched_invalidate_branch_to_parent(self):
        c1 = self.engine.connect()

        with patch.object(self.engine.pool, "logger") as logger:
            c1_branch = c1.connect()
            eq_(c1_branch.execute(select([1])).scalar(), 1)

            self.engine.test_shutdown()

            _assert_invalidated(c1_branch.execute, select([1]))
            assert c1.invalidated
            assert c1_branch.invalidated

            c1_branch._revalidate_connection()
            assert not c1.invalidated
            assert not c1_branch.invalidated

        assert "Invalidate connection" in logger.mock_calls[0][1][0]

    def test_branched_invalidate_parent_to_branch(self):
        c1 = self.engine.connect()

        c1_branch = c1.connect()
        eq_(c1_branch.execute(select([1])).scalar(), 1)

        self.engine.test_shutdown()

        _assert_invalidated(c1.execute, select([1]))
        assert c1.invalidated
        assert c1_branch.invalidated

        c1._revalidate_connection()
        assert not c1.invalidated
        assert not c1_branch.invalidated

    def test_branch_invalidate_state(self):
        c1 = self.engine.connect()

        c1_branch = c1.connect()

        eq_(c1_branch.execute(select([1])).scalar(), 1)

        self.engine.test_shutdown()

        _assert_invalidated(c1_branch.execute, select([1]))
        assert not c1_branch.closed
        assert not c1_branch._connection_is_valid

    def test_ensure_is_disconnect_gets_connection(self):
        def is_disconnect(e, conn, cursor):
            # connection is still present
            assert conn.connection is not None
            # the error usually occurs on connection.cursor(),
            # though MySQLdb we get a non-working cursor.
            # assert cursor is None

        self.engine.dialect.is_disconnect = is_disconnect
        conn = self.engine.connect()
        self.engine.test_shutdown()
        with expect_warnings(
            "An exception has occurred during handling .*",
            py2konly=True
        ):
            assert_raises(
                tsa.exc.DBAPIError,
                conn.execute, select([1])
            )

    def test_rollback_on_invalid_plain(self):
        conn = self.engine.connect()
        trans = conn.begin()
        conn.invalidate()
        trans.rollback()

    @testing.requires.two_phase_transactions
    def test_rollback_on_invalid_twophase(self):
        conn = self.engine.connect()
        trans = conn.begin_twophase()
        conn.invalidate()
        trans.rollback()

    @testing.requires.savepoints
    def test_rollback_on_invalid_savepoint(self):
        conn = self.engine.connect()
        trans = conn.begin()
        trans2 = conn.begin_nested()
        conn.invalidate()
        trans2.rollback()

    def test_invalidate_twice(self):
        conn = self.engine.connect()
        conn.invalidate()
        conn.invalidate()

    @testing.skip_if(
        [lambda: util.py3k, "oracle+cx_oracle"],
        "Crashes on py3k+cx_oracle")
    def test_explode_in_initializer(self):
        engine = engines.testing_engine()

        def broken_initialize(connection):
            connection.execute("select fake_stuff from _fake_table")

        engine.dialect.initialize = broken_initialize

        # raises a DBAPIError, not an AttributeError
        assert_raises(exc.DBAPIError, engine.connect)

    @testing.skip_if(
        [lambda: util.py3k, "oracle+cx_oracle"],
        "Crashes on py3k+cx_oracle")
    def test_explode_in_initializer_disconnect(self):
        engine = engines.testing_engine()

        def broken_initialize(connection):
            connection.execute("select fake_stuff from _fake_table")

        engine.dialect.initialize = broken_initialize

        p1 = engine.pool

        def is_disconnect(e, conn, cursor):
            return True

        engine.dialect.is_disconnect = is_disconnect

        # invalidate() also doesn't screw up
        assert_raises(exc.DBAPIError, engine.connect)

    def test_null_pool(self):
        engine = \
            engines.reconnecting_engine(options=dict(poolclass=pool.NullPool))
        conn = engine.connect()
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.closed
        engine.test_shutdown()
        _assert_invalidated(conn.execute, select([1]))
        assert not conn.closed
        assert conn.invalidated
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.invalidated

    def test_close(self):
        conn = self.engine.connect()
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.closed

        self.engine.test_shutdown()

        _assert_invalidated(conn.execute, select([1]))

        conn.close()
        conn = self.engine.connect()
        eq_(conn.execute(select([1])).scalar(), 1)

    def test_with_transaction(self):
        conn = self.engine.connect()
        trans = conn.begin()
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.closed
        self.engine.test_shutdown()
        _assert_invalidated(conn.execute, select([1]))
        assert not conn.closed
        assert conn.invalidated
        assert trans.is_active
        assert_raises_message(
            tsa.exc.StatementError,
            "Can't reconnect until invalid transaction is rolled back",
            conn.execute, select([1]))
        assert trans.is_active
        assert_raises_message(
            tsa.exc.InvalidRequestError,
            "Can't reconnect until invalid transaction is rolled back",
            trans.commit
        )
        assert trans.is_active
        trans.rollback()
        assert not trans.is_active
        assert conn.invalidated
        eq_(conn.execute(select([1])).scalar(), 1)
        assert not conn.invalidated


class RecycleTest(fixtures.TestBase):
    __backend__ = True

    def test_basic(self):
        for threadlocal in False, True:
            engine = engines.reconnecting_engine(
                options={'pool_threadlocal': threadlocal})

            conn = engine.contextual_connect()
            eq_(conn.execute(select([1])).scalar(), 1)
            conn.close()

            # set the pool recycle down to 1.
            # we aren't doing this inline with the
            # engine create since cx_oracle takes way
            # too long to create the 1st connection and don't
            # want to build a huge delay into this test.

            engine.pool._recycle = 1

            # kill the DB connection
            engine.test_shutdown()

            # wait until past the recycle period
            time.sleep(2)

            # can connect, no exception
            conn = engine.contextual_connect()
            eq_(conn.execute(select([1])).scalar(), 1)
            conn.close()


class PrePingRealTest(fixtures.TestBase):
    __backend__ = True

    def test_pre_ping_db_is_restarted(self):
        engine = engines.reconnecting_engine(
            options={"pool_pre_ping": True}
        )

        conn = engine.connect()
        eq_(conn.execute(select([1])).scalar(), 1)
        stale_connection = conn.connection.connection
        conn.close()

        engine.test_shutdown()
        engine.test_restart()

        conn = engine.connect()
        eq_(conn.execute(select([1])).scalar(), 1)
        conn.close()

        def exercise_stale_connection():
            curs = stale_connection.cursor()
            curs.execute("select 1")

        assert_raises(
            engine.dialect.dbapi.Error,
            exercise_stale_connection
        )

    def test_pre_ping_db_stays_shutdown(self):
        engine = engines.reconnecting_engine(
            options={"pool_pre_ping": True}
        )

        conn = engine.connect()
        eq_(conn.execute(select([1])).scalar(), 1)
        conn.close()

        engine.test_shutdown(stop=True)

        assert_raises(
            exc.DBAPIError,
            engine.connect
        )


class InvalidateDuringResultTest(fixtures.TestBase):
    __backend__ = True

    def setup(self):
        self.engine = engines.reconnecting_engine()
        self.meta = MetaData(self.engine)
        table = Table(
            'sometable', self.meta,
            Column('id', Integer, primary_key=True),
            Column('name', String(50)))
        self.meta.create_all()
        table.insert().execute(
            [{'id': i, 'name': 'row %d' % i} for i in range(1, 100)]
        )

    def teardown(self):
        self.meta.drop_all()
        self.engine.dispose()

    @testing.crashes(
        "oracle",
        "cx_oracle 6 doesn't allow a close like this due to open cursors")
    @testing.fails_if([
        '+mysqlconnector', '+mysqldb', '+cymysql', '+pymysql', '+pg8000'],
        "Buffers the result set and doesn't check for connection close")
    def test_invalidate_on_results(self):
        conn = self.engine.connect()
        result = conn.execute('select * from sometable')
        for x in range(20):
            result.fetchone()
        self.engine.test_shutdown()
        _assert_invalidated(result.fetchone)
        assert conn.invalidated
