Make column-level collation quoting dialect-specific

Fixed regression in 1.2 where newly repaired quoting
of collation names in :ticket:`3785` breaks SQL Server,
which explicitly does not understand a quoted collation
name.   Whether or not mixed-case collation names are
quoted or not is now deferred down to a dialect-level
decision so that each dialect can prepare these identifiers
directly.

Change-Id: Iaf0a8123d9bf4711219e320896bb28c5d2649304
Fixes: #4154

2 files changed, 54 insertions, 0 deletions

diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index b89d149d6..cc9e074ef 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -757,6 +757,20 @@ class SuiteRequirements(Requirements):
         return exclusions.closed()
 
     @property
+    def order_by_collation(self):
+        def check(config):
+            try:
+                self.get_order_by_collation(config)
+                return False
+            except NotImplementedError:
+                return True
+
+        return exclusions.skip_if(check)
+
+    def get_order_by_collation(self, config):
+        raise NotImplementedError()
+
+    @property
     def unicode_connections(self):
         """Target driver must support non-ASCII characters being passed at
         all.
diff --git a/lib/sqlalchemy/testing/suite/test_select.py b/lib/sqlalchemy/testing/suite/test_select.py
index df638c140..d9755c8f9 100644
--- a/lib/sqlalchemy/testing/suite/test_select.py
+++ b/lib/sqlalchemy/testing/suite/test_select.py
@@ -9,6 +9,46 @@ from sqlalchemy import literal_column
 from ..schema import Table, Column
 
 
+class CollateTest(fixtures.TablesTest):
+    __backend__ = True
+
+    @classmethod
+    def define_tables(cls, metadata):
+        Table("some_table", metadata,
+              Column('id', Integer, primary_key=True),
+              Column('data', String(100))
+              )
+
+    @classmethod
+    def insert_data(cls):
+        config.db.execute(
+            cls.tables.some_table.insert(),
+            [
+                {"id": 1, "data": "collate data1"},
+                {"id": 2, "data": "collate data2"},
+            ]
+        )
+
+    def _assert_result(self, select, result):
+        eq_(
+            config.db.execute(select).fetchall(),
+            result
+        )
+
+    @testing.requires.order_by_collation
+    def test_collate_order_by(self):
+        collation = testing.requires.get_order_by_collation(testing.config)
+
+        self._assert_result(
+            select([self.tables.some_table]).
+            order_by(self.tables.some_table.c.data.collate(collation).asc()),
+            [
+                (1, "collate data1"),
+                (2, "collate data2"),
+            ]
+        )
+
+
 class OrderByLabelTest(fixtures.TablesTest):
     """Test the dialect sends appropriate ORDER BY expressions when
     labels are used.