1 files changed, 69 insertions, 0 deletions
diff --git a/lib/sqlalchemy/testing/config.py b/lib/sqlalchemy/testing/config.py
index 64f578dab..20af3dd2e 100644
--- a/lib/sqlalchemy/testing/config.py
+++ b/lib/sqlalchemy/testing/config.py
@@ -4,5 +4,74 @@
 # This module is part of SQLAlchemy and is released under
 # the MIT License: http://www.opensource.org/licenses/mit-license.php
 
+import collections
+
 requirements = None
 db = None
+db_url = None
+db_opts = None
+file_config = None
+
+_current = None
+
+class Config(object):
+    def __init__(self, db, db_opts, options, file_config):
+        self.db = db
+        self.db_opts = db_opts
+        self.options = options
+        self.file_config = file_config
+
+    _stack = collections.deque()
+    _configs = {}
+
+    @classmethod
+    def register(cls, db, db_opts, options, file_config, namespace):
+        """add a config as one of the global configs.
+
+        If there are no configs set up yet, this config also
+        gets set as the "_current".
+        """
+        cfg = Config(db, db_opts, options, file_config)
+
+        global _current
+        if not _current:
+            cls.set_as_current(cfg, namespace)
+        cls._configs[cfg.db.name] = cfg
+        cls._configs[(cfg.db.name, cfg.db.dialect)] = cfg
+        cls._configs[cfg.db] = cfg
+
+    @classmethod
+    def set_as_current(cls, config, namespace):
+        global db, _current, db_url
+        _current = config
+        db_url = config.db.url
+        namespace.db = db = config.db
+
+    @classmethod
+    def push_engine(cls, db, namespace):
+        assert _current, "Can't push without a default Config set up"
+        cls.push(
+            Config(db, _current.db_opts, _current.options, _current.file_config),
+            namespace
+        )
+
+    @classmethod
+    def push(cls, config, namespace):
+        cls._stack.append(_current)
+        cls.set_as_current(config, namespace)
+
+    @classmethod
+    def reset(cls, namespace):
+        if cls._stack:
+            cls.set_as_current(cls._stack[0], namespace)
+            cls._stack.clear()
+
+    @classmethod
+    def all_configs(cls):
+        for cfg in set(cls._configs.values()):
+            yield cfg
+
+    @classmethod
+    def all_dbs(cls):
+        for cfg in cls.all_configs():
+            yield cfg.db