Refactor dialect tests for combinations

Dialect tests tend to have a lot of lists of types,
SQL constructs etc, convert as many of these to @combinations
as possible.

This is exposing that we don't have per-combination
exclusion rules set up which is making things a little bit
cumbersome.

Also set up a fixture that does metadata + DDL.

Change-Id: Ief820e48c9202982b0b1e181b87862490cd7b0c3

1 files changed, 24 insertions, 0 deletions

diff --git a/lib/sqlalchemy/testing/util.py b/lib/sqlalchemy/testing/util.py
index 219511ea0..64738ad2f 100644
--- a/lib/sqlalchemy/testing/util.py
+++ b/lib/sqlalchemy/testing/util.py
@@ -211,6 +211,30 @@ def provide_metadata(fn, *args, **kw):
         self.metadata = prev_meta
 
 
+def metadata_fixture(ddl="function"):
+    """Provide MetaData for a pytest fixture."""
+
+    from . import config
+
+    def decorate(fn):
+        def run_ddl(self):
+            from sqlalchemy import schema
+
+            metadata = self.metadata = schema.MetaData()
+            try:
+                result = fn(self, metadata)
+                metadata.create_all(config.db)
+                # TODO:
+                # somehow get a per-function dml erase fixture here
+                yield result
+            finally:
+                metadata.drop_all(config.db)
+
+        return config.fixture(scope=ddl)(run_ddl)
+
+    return decorate
+
+
 def force_drop_names(*names):
     """Force the given table names to be dropped after test complete,
     isolating for foreign key cycles