[DRAFT] Add Model Registry to Unified SDK

python/kubeflow/model_registry/__init__.py

@@ -0,0 +1,14 @@
+# Re-export ModelRegistry from the standalone model-registry package
+# This allows users to import from kubeflow.model_registry while
+# maintaining backward compatibility with the standalone package
+
+try:
+    from model_registry import ModelRegistry as ModelRegistryClient
+except ImportError as e:
+    raise ImportError(
+        "model-registry package is required. Install with: pip install model-registry"
+    ) from e
+
+__all__ = [
+    "ModelRegistryClient",
+]

python/kubeflow/model_registry/tests/test_import.py

@@ -0,0 +1,102 @@
+import pytest
+import sys
+
+
+@pytest.mark.model_registry
+def test_import_model_registry_available():
+    """Test that ModelRegistry can be imported when model-registry package is available."""
+    try:
+        from kubeflow.model_registry import ModelRegistry, ModelRegistryClient
+        from model_registry import ModelRegistry as OriginalModelRegistry
+
+        # Verify they are the same class
+        assert ModelRegistry is OriginalModelRegistry
+        assert ModelRegistryClient is OriginalModelRegistry
+
+    except ImportError:
+        pytest.skip("model-registry package is not installed")
+
+
+@pytest.mark.model_registry
+def test_import_model_registry_client_available():
+    """Test that ModelRegistryClient is an alias for ModelRegistry."""
+    try:
+        from kubeflow.model_registry import ModelRegistryClient, ModelRegistry
+
+        # Verify ModelRegistryClient is an alias for ModelRegistry
+        assert ModelRegistryClient is ModelRegistry
+
+    except ImportError:
+        pytest.skip("model-registry package is not installed")
+
+
+@pytest.mark.model_registry
+def test_import_error_when_model_registry_not_installed(monkeypatch):
+    """Test that a helpful error is raised when model-registry is not available."""
+    # Remove the module from sys.modules if it exists
+    modules_to_remove = ["kubeflow.model_registry", "model_registry", "model_registry._client"]
+    original_modules = {}
+
+    for module_name in modules_to_remove:
+        if module_name in sys.modules:
+            original_modules[module_name] = sys.modules[module_name]
+            del sys.modules[module_name]
+
+    # Store the original import function to avoid recursion
+    original_import = __import__
+
+    def mock_import(name, *args, **kwargs):
+        if name == "model_registry":
+            raise ImportError("No module named 'model_registry'")
+        return original_import(name, *args, **kwargs)
+
+    monkeypatch.setattr("builtins.__import__", mock_import)
+
+    try:
+        with pytest.raises(ImportError) as exc_info:
+            import kubeflow.model_registry  # noqa: F401
+
+        # Verify the error message is helpful
+        assert "model-registry package is required" in str(exc_info.value)
+        assert "pip install model-registry" in str(exc_info.value)
+
+    finally:
+        # Restore the original modules
+        for module_name, module in original_modules.items():
+            sys.modules[module_name] = module
+
+
+@pytest.mark.model_registry
+def test_all_exports_available():
+    """Test that all expected exports are available in the module."""
+    try:
+        import kubeflow.model_registry as mr_module
+
+        # Check that __all__ contains expected items
+        expected_exports = ["ModelRegistry", "ModelRegistryClient"]
+        assert hasattr(mr_module, "__all__")
+        assert set(mr_module.__all__) == set(expected_exports)
+
+        # Check that all items in __all__ are actually available
+        for export in expected_exports:
+            assert hasattr(mr_module, export)
+
+    except ImportError:
+        pytest.skip("model-registry package is not installed")
+
+
+@pytest.mark.model_registry
+def test_import_via_star_import():
+    """Test that star imports work correctly."""
+    try:
+        # This is a bit tricky to test directly, so we'll check the namespace
+        import kubeflow.model_registry as mr_module
+
+        # Simulate what 'from kubeflow.model_registry import *' would do
+        star_imports = {name: getattr(mr_module, name) for name in mr_module.__all__}
+
+        assert "ModelRegistryClient" in star_imports
+        assert star_imports["ModelRegistry"] is star_imports["ModelRegistryClient"]
+
+    except ImportError:
+        pytest.skip("model-registry package is not installed")

python/pyproject.toml

@@ -31,6 +31,9 @@ dependencies = [
   "kubeflow-trainer-api>=2.0.0",
 ]
 [project.optional-dependencies]
+model-registry = [
+  "model-registry>=0.2.21",
+]
 dev = [
   "pytest>=7.0",
   "pytest-mock>=3.10",