improve autogen rendering for PG ExcludeConstraint

Fixed issue regarding PostgreSQL :class:`.ExcludeConstraint`, where
constraint elements which made use of :func:`.literal_column` could not be
rendered for autogenerate. Additionally, using SQLAlchemy 2.0.5 or greater,
:func:`.text()` constructs are also supported within PostgreSQL
:class:`.ExcludeConstraint` objects for autogenerate render. Pull request
courtesy Jan Katins.

Fixes: #1184
Closes: #1185
Pull-request: https://github.com/sqlalchemy/alembic/pull/1185
Pull-request-sha: 68360ce9aa746a85407c5e1e04b8021123d98504

Change-Id: I302f3f4007a186ffac13b344ff6769dd302f28f5

1 files changed, 59 insertions, 0 deletions

diff --git a/tests/test_postgresql.py b/tests/test_postgresql.py
index a8c284d..18f50ce 100644
--- a/tests/test_postgresql.py
+++ b/tests/test_postgresql.py
@@ -28,6 +28,7 @@ from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.sql import column
 from sqlalchemy.sql import false
 from sqlalchemy.sql import table
+from sqlalchemy.sql.expression import literal_column
 
 from alembic import autogenerate
 from alembic import command
@@ -1156,6 +1157,64 @@ class PostgresqlAutogenRenderTest(TestBase):
             "name='TExclX'))",
         )
 
+    def test_inline_exclude_constraint_literal_column(self):
+        """test for #1184"""
+
+        autogen_context = self.autogen_context
+
+        m = MetaData()
+        t = Table(
+            "TTable",
+            m,
+            Column("id", String()),
+            ExcludeConstraint(
+                (literal_column("id + 2"), "="), name="TExclID", using="gist"
+            ),
+        )
+
+        op_obj = ops.CreateTableOp.from_table(t)
+
+        eq_ignore_whitespace(
+            autogenerate.render_op_text(autogen_context, op_obj),
+            "op.create_table('TTable',sa.Column('id', sa.String(), "
+            "nullable=True),"
+            "postgresql.ExcludeConstraint((sa.literal_column('id + 2'), '='), "
+            "using='gist', "
+            "name='TExclID'))",
+        )
+
+    @config.requirements.sqlalchemy_2
+    def test_inline_exclude_constraint_text(self):
+        """test for #1184.
+
+        Requires SQLAlchemy 2.0.5 due to issue
+        https://github.com/sqlalchemy/sqlalchemy/issues/9401
+
+        """
+
+        autogen_context = self.autogen_context
+
+        m = MetaData()
+        t = Table(
+            "TTable",
+            m,
+            Column("id", String()),
+            ExcludeConstraint(
+                (text("id + 2"), "="), name="TExclID", using="gist"
+            ),
+        )
+
+        op_obj = ops.CreateTableOp.from_table(t)
+
+        eq_ignore_whitespace(
+            autogenerate.render_op_text(autogen_context, op_obj),
+            "op.create_table('TTable',sa.Column('id', sa.String(), "
+            "nullable=True),"
+            "postgresql.ExcludeConstraint((sa.text('id + 2'), '='), "
+            "using='gist', "
+            "name='TExclID'))",
+        )
+
     def test_json_type(self):
         eq_ignore_whitespace(
             autogenerate.render._repr_type(JSON(), self.autogen_context),