Add streaming tests and migrate Redis/Snowflake loaders

Adds generalized streaming test infrastructure and migrates Redis and
Snowflake loader tests to use the shared base classes.

Author: fordN

tests/integration/loaders/backends/test_postgresql.py

@@ -14,6 +14,7 @@
     from src.amp.loaders.implementations.postgresql_loader import PostgreSQLLoader
     from tests.integration.loaders.conftest import LoaderTestConfig
     from tests.integration.loaders.test_base_loader import BaseLoaderTests
+    from tests.integration.loaders.test_base_streaming import BaseStreamingTests
 except ImportError:
     pytest.skip('amp modules not available', allow_module_level=True)
 
@@ -109,6 +110,13 @@ class TestPostgreSQLCore(BaseLoaderTests):
     config = PostgreSQLTestConfig()
 
 
+@pytest.mark.postgresql
+class TestPostgreSQLStreaming(BaseStreamingTests):
+    """PostgreSQL streaming tests (inherited from base)"""
+
+    config = PostgreSQLTestConfig()
+
+
 @pytest.fixture
 def cleanup_tables(postgresql_test_config):
     """Cleanup test tables after tests"""