clean up the dialect selection thing here

1 files changed, 12 insertions, 8 deletions

diff --git a/lib/sqlalchemy/testing/assertions.py b/lib/sqlalchemy/testing/assertions.py
index 592467302..96a8bc023 100644
--- a/lib/sqlalchemy/testing/assertions.py
+++ b/lib/sqlalchemy/testing/assertions.py
@@ -184,15 +184,19 @@ class AssertsCompiledSQL(object):
                         allow_dialect_select=False):
         if use_default_dialect:
             dialect = default.DefaultDialect()
-        elif dialect == None and not allow_dialect_select:
-            dialect = getattr(self, '__dialect__', None)
+        elif allow_dialect_select:
+            dialect = None
+        else:
+            if dialect is None:
+                dialect = getattr(self, '__dialect__', None)
+
+            if dialect is None:
+                dialect = config.db.dialect
+            elif dialect == 'default':
+                dialect = default.DefaultDialect()
+            elif isinstance(dialect, util.string_types):
+                dialect = create_engine("%s://" % dialect).dialect
 
-        if dialect == 'default':
-            dialect = default.DefaultDialect()
-        elif dialect is None:
-            dialect = config.db.dialect
-        elif isinstance(dialect, util.string_types):
-            dialect = create_engine("%s://" % dialect).dialect
 
         kw = {}
         if params is not None: