Accommodate SQLAlchemy 1.4/2.0

To accommodate SQLAlchemy 1.4 and 2.0, the migration model now no longer
assumes that the SQLAlchemy Connection will autocommit an individual
operation.   This essentially means that for databases that use
non-transactional DDL (pysqlite current driver behavior, MySQL), there is
still a BEGIN/COMMIT block that will surround each individual migration.
Databases that support transactional DDL should continue to have the
same flow, either per migration or per-entire run, depending on the
value of the :paramref:`.Environment.configure.transaction_per_migration`
flag.

Compatibility is established such that the entire library should
not generate any SQLAlchemy 2.0 deprecation warnings and
SQLALCHEMY_WARN_20 is part of conftest.py. (one warning remains
for the moment that needs to be resolved on the SQLAlchemy side)

The test suite requires SQLAlchemy 1.4.0b2 for testing 1.4;
1.4.0b1 won't work.

Test suite / setup also being modernized, as we are at
SQLAlchemy 1.3 we can now remove the majority of the testing
suite plugin.

Change-Id: If55b1ea3c12ead66405ab3fadc76d15d89dabb90

1 files changed, 11 insertions, 18 deletions

diff --git a/tests/test_environment.py b/tests/test_environment.py
index 4fb6bbe..63de6cd 100644
--- a/tests/test_environment.py
+++ b/tests/test_environment.py
@@ -1,6 +1,7 @@
 #!coding: utf-8
 from alembic import command
 from alembic import testing
+from alembic import util
 from alembic.environment import EnvironmentContext
 from alembic.migration import MigrationContext
 from alembic.script import ScriptDirectory
@@ -11,7 +12,7 @@ from alembic.testing import is_
 from alembic.testing import is_false
 from alembic.testing import is_true
 from alembic.testing import mock
-from alembic.testing.assertions import expect_warnings
+from alembic.testing.assertions import expect_raises_message
 from alembic.testing.env import _no_sql_testing_config
 from alembic.testing.env import _sqlite_file_db
 from alembic.testing.env import clear_staging_env
@@ -94,10 +95,11 @@ def upgrade():
             command.upgrade(self.cfg, "arev", sql=True)
         assert "do some SQL thing with a % percent sign %" in buf.getvalue()
 
+    @config.requirements.legacy_engine
     @testing.uses_deprecated(
         r"The Engine.execute\(\) function/method is considered legacy"
     )
-    def test_warning_on_passing_engine(self):
+    def test_error_on_passing_engine(self):
         env = self._fixture()
 
         engine = _sqlite_file_db()
@@ -131,18 +133,15 @@ def downgrade():
             migration_fn(rev, context)
             return env.script._upgrade_revs(a_rev, rev)
 
-        with expect_warnings(
+        with expect_raises_message(
+            util.CommandError,
             r"'connection' argument to configure\(\) is "
-            r"expected to be a sqlalchemy.engine.Connection "
+            r"expected to be a sqlalchemy.engine.Connection ",
         ):
             env.configure(
                 connection=engine, fn=upgrade, transactional_ddl=False
             )
 
-        env.run_migrations()
-
-        eq_(migration_fn.mock_calls, [mock.call((), env._migration_context)])
-
 
 class MigrationTransactionTest(TestBase):
     __backend__ = True
@@ -238,7 +237,7 @@ class MigrationTransactionTest(TestBase):
         with context.begin_transaction():
             is_false(self.conn.in_transaction())
             with context.begin_transaction(_per_migration=True):
-                is_false(self.conn.in_transaction())
+                is_true(self.conn.in_transaction())
 
             is_false(self.conn.in_transaction())
         is_false(self.conn.in_transaction())
@@ -264,7 +263,7 @@ class MigrationTransactionTest(TestBase):
         with context.begin_transaction():
             is_false(self.conn.in_transaction())
             with context.begin_transaction(_per_migration=True):
-                is_false(self.conn.in_transaction())
+                is_true(self.conn.in_transaction())
 
             is_false(self.conn.in_transaction())
         is_false(self.conn.in_transaction())
@@ -334,18 +333,12 @@ class MigrationTransactionTest(TestBase):
         with context.begin_transaction():
             is_false(self.conn.in_transaction())
             with context.begin_transaction(_per_migration=True):
-                if context.impl.transactional_ddl:
-                    is_true(self.conn.in_transaction())
-                else:
-                    is_false(self.conn.in_transaction())
+                is_true(self.conn.in_transaction())
 
                 with context.autocommit_block():
                     is_false(self.conn.in_transaction())
 
-                if context.impl.transactional_ddl:
-                    is_true(self.conn.in_transaction())
-                else:
-                    is_false(self.conn.in_transaction())
+                is_true(self.conn.in_transaction())
 
             is_false(self.conn.in_transaction())
         is_false(self.conn.in_transaction())