warn and skip for FKs that refer to invisible cols for Oracle

Supported use case for foreign key constraints where the local column is
marked as "invisible". The errors normally generated when a
:class:`.ForeignKeyConstraint` is created that check for the target column
are disabled when reflecting, and the constraint is skipped with a warning
in the same way which already occurs for an :class:`.Index` with a similar
issue.

tests are added for indexes, unique constraints, and primary key
constraints, which were already working; indexes and uniques warn,
primary keys don't which we would assume is because we never see those
PK columns in the first place.

Constraints now raise an informative ConstraintColumnNotFoundError
in the general case for strings in the "pending colargs" collection
not being resolvable.

Fixes: #9059
Change-Id: I400cf0bff6abba0e0c75f38b07617be1a8ec3453

1 files changed, 6 insertions, 5 deletions

diff --git a/test/sql/test_metadata.py b/test/sql/test_metadata.py
index 56bb89541..7f6bee72b 100644
--- a/test/sql/test_metadata.py
+++ b/test/sql/test_metadata.py
@@ -3946,11 +3946,12 @@ class ConstraintTest(fixtures.TestBase):
 
     def test_raise_index_nonexistent_name(self):
         m = MetaData()
-        # the KeyError isn't ideal here, a nicer message
-        # perhaps
-        assert_raises(
-            KeyError, Table, "t", m, Column("x", Integer), Index("foo", "q")
-        )
+
+        with expect_raises_message(
+            exc.ConstraintColumnNotFoundError,
+            "Can't create Index on table 't': no column named 'q' is present.",
+        ):
+            Table("t", m, Column("x", Integer), Index("foo", "q"))
 
     def test_raise_not_a_column(self):
         assert_raises(exc.ArgumentError, Index, "foo", 5)