- this pymssql test needs to be against the pymssql dialect

- Part of a longer series of fixes needed for pyodbc+
      mssql, a CAST to NVARCHAR(max) has been added to the bound
      parameter for the table name and schema name in all information schema
      queries to avoid the issue of comparing NVARCHAR to NTEXT,
      which seems to be rejected by the ODBC driver in some cases,
      such as FreeTDS (0.91 only?) plus unicode bound parameters being passed.
      The issue seems to be specific to the SQL Server information
      schema tables and the workaround is harmless for those cases
      where the problem doesn't exist in the first place.
[ticket:2355]

doc/build/changelog/changelog_08.rst

@@ -6,6 +6,20 @@
 .. changelog::
     :version: 0.8.1
 
+    .. change::
+      :tags: bug, mssql
+      :tickets: 2355
+
+      Part of a longer series of fixes needed for pyodbc+
+      mssql, a CAST to NVARCHAR(max) has been added to the bound
+      parameter for the table name and schema name in all information schema
+      queries to avoid the issue of comparing NVARCHAR to NTEXT,
+      which seems to be rejected by the ODBC driver in some cases,
+      such as FreeTDS (0.91 only?) plus unicode bound parameters being passed.
+      The issue seems to be specific to the SQL Server information
+      schema tables and the workaround is harmless for those cases
+      where the problem doesn't exist in the first place.
+
     .. change::
       :tags: bug, sql
       :tickets: 2691

lib/sqlalchemy/dialects/mssql/information_schema.py

@@ -8,6 +8,7 @@
 
 from ... import Table, MetaData, Column
 from ...types import String, Unicode, Integer, TypeDecorator
+from ... import cast
 
 ischema = MetaData()
 
@@ -22,6 +23,9 @@ class CoerceUnicode(TypeDecorator):
         # end Py2K
         return value
 
+    def bind_expression(self, bindvalue):
+        return cast(bindvalue, Unicode)
+
 schemata = Table("SCHEMATA", ischema,
     Column("CATALOG_NAME", CoerceUnicode, key="catalog_name"),
     Column("SCHEMA_NAME", CoerceUnicode, key="schema_name"),

test/dialect/test_mssql.py

@@ -1949,7 +1949,7 @@ class TypeRoundTripTest(fixtures.TestBase, AssertsExecutionResults, ComparesTabl
                 engine.execute(tbl.delete())
 
 class MonkeyPatchedBinaryTest(fixtures.TestBase):
-    __only_on__ = 'mssql'
+    __only_on__ = 'mssql+pymssql'
 
     def test_unicode(self):
         module = __import__('pymssql')