Tests: Test composite synthetic uniqueness constraints

src/sqlalchemy_cratedb/support/polyfill.py

@@ -38,7 +38,10 @@ def check_uniqueness_factory(sa_entity, *attribute_names):
 
     This is used by CrateDB's MLflow adapter.
 
+    TODO: Maybe add to some helper function?
     TODO: Maybe enable through a dialect parameter `crate_polyfill_unique` or such.
+    TODO: Maybe derive from the model definition itself?
+          __table_args__ = (sa.UniqueConstraint("name", "user_id", name="unique_name_user"),)
     """
 
     # Synthesize a canonical "name" for the constraint,

tests/test_support_polyfill.py

@@ -74,7 +74,7 @@ class FooBar(Base):
         name = sa.Column(sa.String)
 
     # Add synthetic UNIQUE constraint on `name` column.
-    listen(FooBar, "before_insert", check_uniqueness_factory(FooBar, "name"))
+    listen(FooBar, "before_insert", check_uniqueness_factory(FooBar, "id", "name"))
 
     Base.metadata.drop_all(engine, checkfirst=True)
     Base.metadata.create_all(engine, checkfirst=True)
@@ -86,11 +86,11 @@ class FooBar(Base):
     session.execute(sa.text("REFRESH TABLE foobar"))
 
     # Insert second record, violating the uniqueness constraint.
-    bar_item = FooBar(id="bar", name="foo")
+    bar_item = FooBar(id="foo", name="foo")
     session.add(bar_item)
     with pytest.raises(IntegrityError) as ex:
         session.commit()
-    assert ex.match("DuplicateKeyException in table 'foobar' on constraint 'name'")
+    assert ex.match("DuplicateKeyException in table 'foobar' on constraint 'id-name'")
 
 
 @pytest.mark.skipif(SA_VERSION < SA_1_4, reason="Feature not supported on SQLAlchemy 1.3 and earlier")