add __contains__

dataset/persistence/database.py

@@ -141,6 +141,9 @@ class Database(object):
             set(self.metadata.tables.keys()) | set(self._tables.keys())
         )
 
+    def __contains__(self, member):
+        return member in self.tables
+
     def create_table(self, table_name, primary_id='id', primary_type='Integer'):
         """
         Creates a new table. The new table will automatically have an `id` column

test/test_persistence.py

@@ -38,6 +38,9 @@ class DatabaseTestCase(unittest.TestCase):
     def test_tables(self):
         assert self.db.tables == ['weather'], self.db.tables
 
+    def test_contains(self):
+        assert 'weather' in self.db, self.db.tables
+
     def test_create_table(self):
         table = self.db['foo']
         assert table.table.exists()