BUG: Adds version checking to AssetFinder init

tests/test_assets.py

@@ -1333,3 +1333,24 @@ class TestAssetDBVersioning(TestCase):
         # Assert that trying to overwrite the version fails
         with self.assertRaises(sa.exc.IntegrityError):
             write_version_info(version_table, -3)
+
+    def test_finder_checks_version(self):
+        # Create an env and give it a bogus version number
+        env = TradingEnvironment(load=noop_load)
+        metadata = sa.MetaData(bind=env.engine)
+        version_table = _version_table_schema(metadata)
+        version_table.delete().execute()
+        write_version_info(version_table, -2)
+        check_version_info(version_table, -2)
+
+        # Assert that trying to build a finder with a bad db raises an error
+        with self.assertRaises(AssetDBVersionError):
+            AssetFinder(engine=env.engine)
+
+        # Change the version number of the db to the correct version
+        version_table.delete().execute()
+        write_version_info(version_table, ASSET_DB_VERSION)
+        check_version_info(version_table, ASSET_DB_VERSION)
+
+        # Now that the versions match, this Finder should succeed
+        AssetFinder(engine=env.engine)

zipline/assets/assets.py

@@ -37,9 +37,13 @@ from zipline.assets import (
     Asset, Equity, Future,
 )
 from zipline.assets.asset_writer import (
+    check_version_info,
     split_delimited_symbol,
     asset_db_table_names,
-    SQLITE_MAX_VARIABLE_NUMBER
+    SQLITE_MAX_VARIABLE_NUMBER,
+)
+from zipline.assets.asset_db_schema import (
+    ASSET_DB_VERSION
 )
 from zipline.utils.control_flow import invert
 
@@ -104,6 +108,9 @@ class AssetFinder(object):
         for table_name in asset_db_table_names:
             setattr(self, table_name, metadata.tables[table_name])
 
+        # Check the version info of the db for compatibility
+        check_version_info(self.version_info, ASSET_DB_VERSION)
+
         # Cache for lookup of assets by sid, the objects in the asset lookup
         # may be shared with the results from equity and future lookup caches.
         #