Add test requirement: indexes_with_ascdesc

There are some tests for indexes that include DESC in the
columns.  Firebird and maybe others don't support this concept,
so put it under a requirement rule.

Fixes: #5106
Closes: #5108
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5108
Pull-request-sha: 4b1560f28a52feb7d4a6c5d828f587a735d6a40b

Change-Id: I4744246005f3af263ea1e028d8a46795b87de62c

2 files changed, 11 insertions, 2 deletions

diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index b3375f6d5..03d76eccb 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -552,6 +552,11 @@ class SuiteRequirements(Requirements):
         return exclusions.open()
 
     @property
+    def indexes_with_ascdesc(self):
+        """target database supports CREATE INDEX with per-column ASC/DESC."""
+        return exclusions.open()
+
+    @property
     def indexes_with_expressions(self):
         """target database supports CREATE INDEX against SQL expressions."""
         return exclusions.closed()
diff --git a/lib/sqlalchemy/testing/suite/test_reflection.py b/lib/sqlalchemy/testing/suite/test_reflection.py
index 9b6cec10c..85e193d8e 100644
--- a/lib/sqlalchemy/testing/suite/test_reflection.py
+++ b/lib/sqlalchemy/testing/suite/test_reflection.py
@@ -292,8 +292,10 @@ class ComponentReflectionTest(fixtures.TablesTest):
                     Column("q", sa.String(5)),
                     test_needs_fk=True,
                 )
-                Index("noncol_idx_nopk", noncol_idx_test_nopk.c.q.desc())
-                Index("noncol_idx_pk", noncol_idx_test_pk.c.q.desc())
+
+                if testing.requires.indexes_with_ascdesc.enabled:
+                    Index("noncol_idx_nopk", noncol_idx_test_nopk.c.q.desc())
+                    Index("noncol_idx_pk", noncol_idx_test_pk.c.q.desc())
 
         if testing.requires.view_column_reflection.enabled:
             cls.define_views(metadata, schema)
@@ -882,10 +884,12 @@ class ComponentReflectionTest(fixtures.TablesTest):
         eq_(list(t.indexes)[0].name, ixname)
 
     @testing.requires.index_reflection
+    @testing.requires.indexes_with_ascdesc
     def test_get_noncol_index_no_pk(self):
         self._test_get_noncol_index("noncol_idx_test_nopk", "noncol_idx_nopk")
 
     @testing.requires.index_reflection
+    @testing.requires.indexes_with_ascdesc
     def test_get_noncol_index_pk(self):
         self._test_get_noncol_index("noncol_idx_test_pk", "noncol_idx_pk")