- Added new test coverage for so-called "down adaptions" of SQL types,

where a more specific type is adapted to a more generic one - this
use case is needed by some third party tools such as ``sqlacodegen``.
The specific cases that needed repair within this test suite were that
of :class:`.mysql.ENUM` being downcast into a :class:`.types.Enum`,
and that of SQLite date types being cast into generic date types.
The ``adapt()`` method needed to become more specific here to counteract
the removal of a "catch all" ``**kwargs`` collection on the base
:class:`.TypeEngine` class that was removed in 0.9. [ticket:2917]

4 files changed, 43 insertions, 11 deletions

diff --git a/doc/build/changelog/changelog_09.rst b/doc/build/changelog/changelog_09.rst
index d59f3ec60..768326528 100644
--- a/doc/build/changelog/changelog_09.rst
+++ b/doc/build/changelog/changelog_09.rst
@@ -15,6 +15,20 @@
     :version: 0.9.2
 
     .. change::
+        :tags: bug, mysql, sql
+        :tickets: 2917
+
+        Added new test coverage for so-called "down adaptions" of SQL types,
+        where a more specific type is adapted to a more generic one - this
+        use case is needed by some third party tools such as ``sqlacodegen``.
+        The specific cases that needed repair within this test suite were that
+        of :class:`.mysql.ENUM` being downcast into a :class:`.types.Enum`,
+        and that of SQLite date types being cast into generic date types.
+        The ``adapt()`` method needed to become more specific here to counteract
+        the removal of a "catch all" ``**kwargs`` collection on the base
+        :class:`.TypeEngine` class that was removed in 0.9.
+
+    .. change::
         :tags: feature, sql
         :tickets: 2910
 
diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index e45f6ecd8..61698b038 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -1189,9 +1189,10 @@ class ENUM(sqltypes.Enum, _EnumeratedValues):
                 return value
         return process
 
-    def adapt(self, impltype, **kw):
-        kw['strict'] = self.strict
-        return sqltypes.Enum.adapt(self, impltype, **kw)
+    def adapt(self, cls, **kw):
+        if issubclass(cls, ENUM):
+            kw['strict'] = self.strict
+        return sqltypes.Enum.adapt(self, cls, **kw)
 
 
 class SET(_EnumeratedValues):
diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index 579a61046..d8aa58c2c 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -154,11 +154,12 @@ class _DateTimeMixin(object):
             self._storage_format = storage_format
 
     def adapt(self, cls, **kw):
-        if self._storage_format:
-            kw["storage_format"] = self._storage_format
-        if self._reg:
-            kw["regexp"] = self._reg
-        return util.constructor_copy(self, cls, **kw)
+        if issubclass(cls, _DateTimeMixin):
+            if self._storage_format:
+                kw["storage_format"] = self._storage_format
+            if self._reg:
+                kw["regexp"] = self._reg
+        return super(_DateTimeMixin, self).adapt(cls, **kw)
 
     def literal_processor(self, dialect):
         bp = self.bind_processor(dialect)
diff --git a/test/sql/test_types.py b/test/sql/test_types.py
index 3a263aab2..3df19874b 100644
--- a/test/sql/test_types.py
+++ b/test/sql/test_types.py
@@ -114,21 +114,37 @@ class AdaptTest(fixtures.TestBase):
 
         """
 
-        for typ in self._all_types():
+        def adaptions():
+            for typ in self._all_types():
+                up_adaptions = [typ] + typ.__subclasses__()
+                yield False, typ, up_adaptions
+                for subcl in typ.__subclasses__():
+                    if subcl is not typ and \
+                        typ is not TypeDecorator and \
+                        "sqlalchemy" in subcl.__module__:
+                        yield True, subcl, [typ]
+
+        for is_down_adaption, typ, target_adaptions in adaptions():
             if typ in (types.TypeDecorator, types.TypeEngine, types.Variant):
                 continue
             elif typ is dialects.postgresql.ARRAY:
                 t1 = typ(String)
             else:
                 t1 = typ()
-            for cls in [typ] + typ.__subclasses__():
+            for cls in target_adaptions:
                 if not issubclass(typ, types.Enum) and \
                         issubclass(cls, types.Enum):
                     continue
+
+                # print("ADAPT %s -> %s" % (t1.__class__, cls))
                 t2 = t1.adapt(cls)
                 assert t1 is not t2
+
+                if is_down_adaption:
+                    t2, t1 = t1, t2
+
                 for k in t1.__dict__:
-                    if k == 'impl':
+                    if k in ('impl', '_is_oracle_number'):
                         continue
                     # assert each value was copied, or that
                     # the adapted type has a more specific