Raise NotImplementedError when flavor is not supported (#2)

.github/settings.yml

@@ -18,7 +18,7 @@ repository:
   #topics: github, probot
 
   # Either `true` to make the repository private, or `false` to make it public.
-  private: true
+  private: false
 
   # Either `true` to enable issues for this repository, `false` to disable them.
   has_issues: true

setup.py

@@ -66,6 +66,7 @@ def _download_aws_rds_ca_bundle(self):
         "SQLAlchemy dialects to connect to Amazon RDS instances "
         "with IAM authentication"
     ),
+    url="https://github.com/cisco-open/sqlalchemy-rdsiam",
     long_description=_get_readme_contents(),
     long_description_content_type="text/markdown",
     packages=["sqlalchemy_rdsiam"],

sqlalchemy_rdsiam/dialects.py

@@ -38,9 +38,11 @@ def import_dbapi(cls: Type) -> ModuleType:
             return dbapi_psycopg2
 
 except ImportError:
+    from sqlalchemy.dialects.postgresql.base import PGDialect
+
     _has_sqlalchemy_psycopg2 = False
 
-    class PGDialect_psycopg2rdsiam:  # type: ignore
+    class PGDialect_psycopg2rdsiam(PGDialect):  # type: ignore
         @classmethod
         def dbapi(cls: Type) -> ModuleType:
             return cls.import_dbapi()
@@ -77,9 +79,11 @@ def import_dbapi(cls: Type) -> ModuleType:
             return AsyncAdapt_asyncpg_dbapi(asyncpg=dbapi_asyncpg)
 
 except ImportError:
+    from sqlalchemy.dialects.postgresql.base import PGDialect
+
     _has_sqlalchemy_asyncpg = False
 
-    class PGDialect_asyncpgrdsiam:  # type: ignore
+    class PGDialect_asyncpgrdsiam(PGDialect):  # type: ignore
         @classmethod
         def dbapi(cls: Type) -> ModuleType:
             return cls.import_dbapi()

tests/test_connect.py

@@ -82,6 +82,26 @@ def test_connect_region(
         )
 
 
+@pytest.mark.parametrize(
+    "try_connect_fn,engine_prefix",
+    [
+        pytest.param(
+            "try_connect_sync",
+            "postgresql+psycopg2rdsiam",
+            marks=pytest.mark.skipif(
+                _has_sqlalchemy_psycopg2, reason="psycopg2 is available"
+            ),
+        )
+    ],
+)
+def test_dialect_not_available(request, try_connect_fn, engine_prefix):
+    """Check that using an unsupported dialect raises the right error."""
+    try_connect = request.getfixturevalue(try_connect_fn)
+
+    with pytest.raises(NotImplementedError):
+        try_connect(f"{engine_prefix}://some-url")
+
+
 @pytest.mark.skipif(
     not _has_sqlalchemy_psycopg2,
     reason="psycopg2 is not supported",