feat: add alembic config/utility functions, for migrations admin

wuttaweb will have some admin tools exposed soon hopefully

tests/db/test_conf.py

@@ -6,13 +6,18 @@ import tempfile
 from unittest import TestCase
 
 from wuttjamaican.conf import WuttaConfig
+from wuttjamaican.testing import ConfigTestCase, DataTestCase
 
 try:
     import sqlalchemy as sa
     from sqlalchemy import orm
     from sqlalchemy.engine import Engine
     from sqlalchemy.pool import NullPool
+    from alembic import command as alembic_command
+    from alembic.config import Config as AlembicConfig
+    from alembic.script import ScriptDirectory
     from wuttjamaican.db import conf
+    from wuttjamaican.db import conf as mod
 except ImportError:
     pass
 else:
@@ -154,3 +159,111 @@ else:
                 }
             )
             self.assertTrue(engine.pool._pre_ping)
+
+    class TestMakeAlembicConfig(ConfigTestCase):
+
+        def test_defaults(self):
+
+            # without config file
+            self.assertFalse(self.config.files_read)
+            alembic = mod.make_alembic_config(self.config)
+            self.assertIsInstance(alembic, AlembicConfig)
+            self.assertIsNone(alembic.config_file_name)
+            self.assertIsNone(alembic.get_main_option("script_location"))
+            self.assertIsNone(alembic.get_main_option("version_locations"))
+
+            # with config file
+            path = self.write_file("test.ini", "[alembic]")
+            self.config.files_read = [path]
+            alembic = mod.make_alembic_config(self.config)
+            self.assertIsInstance(alembic, AlembicConfig)
+            self.assertEqual(alembic.config_file_name, path)
+            self.assertIsNone(alembic.get_main_option("script_location"))
+            self.assertIsNone(alembic.get_main_option("version_locations"))
+
+        def test_configured(self):
+            self.config.setdefault("alembic.script_location", "wuttjamaican.db:alembic")
+            self.config.setdefault(
+                "alembic.version_locations", "wuttjamaican.db:alembic/versions"
+            )
+
+            alembic = mod.make_alembic_config(self.config)
+            self.assertIsInstance(alembic, AlembicConfig)
+            self.assertEqual(
+                alembic.get_main_option("script_location"), "wuttjamaican.db:alembic"
+            )
+            self.assertEqual(
+                alembic.get_main_option("version_locations"),
+                "wuttjamaican.db:alembic/versions",
+            )
+
+    class TestGetAlembicScriptdir(ConfigTestCase):
+
+        def test_basic(self):
+            self.config.setdefault("alembic.script_location", "wuttjamaican.db:alembic")
+            self.config.setdefault(
+                "alembic.version_locations", "wuttjamaican.db:alembic/versions"
+            )
+
+            # can provide alembic config
+            alembic = mod.make_alembic_config(self.config)
+            script = mod.get_alembic_scriptdir(self.config, alembic)
+            self.assertIsInstance(script, ScriptDirectory)
+
+            # but also can omit it
+            script = mod.get_alembic_scriptdir(self.config)
+            self.assertIsInstance(script, ScriptDirectory)
+
+    class TestCheckAlembicCurrent(DataTestCase):
+
+        def make_config(self, **kwargs):
+            sqlite_path = self.write_file("test.sqlite", "")
+            self.sqlite_engine_url = f"sqlite:///{sqlite_path}"
+
+            config_path = self.write_file(
+                "test.ini",
+                f"""
+[wutta.db]
+default.url = {self.sqlite_engine_url}
+
+[alembic]
+script_location = wuttjamaican.db:alembic
+version_locations = wuttjamaican.db:alembic/versions
+""",
+            )
+
+            return super().make_config([config_path], **kwargs)
+
+        def test_basic(self):
+            alembic = mod.make_alembic_config(self.config)
+            self.assertIsNotNone(alembic.get_main_option("script_location"))
+            self.assertIsNotNone(alembic.get_main_option("version_locations"))
+
+            # false by default, since tests use MetaData.create_all()
+            # instead of migrations for setup
+            self.assertFalse(mod.check_alembic_current(self.config, alembic))
+
+            # and to further prove the point, alembic_version table is missing
+            self.assertEqual(
+                self.session.execute(sa.text("select count(*) from person")).scalar(),
+                0,
+            )
+            self.assertRaises(
+                sa.exc.OperationalError,
+                self.session.execute,
+                sa.text("select count(*) from alembic_version"),
+            )
+
+            # but we can 'stamp' the DB to declare its current revision
+            alembic_command.stamp(alembic, "heads")
+
+            # now the alembic_version table exists
+            self.assertEqual(
+                self.session.execute(
+                    sa.text("select count(*) from alembic_version")
+                ).scalar(),
+                1,
+            )
+
+            # and now Alembic knows we are current
+            self.assertTrue(mod.check_alembic_current(self.config, alembic))