Fix optional dependency handling for Redis and MinIO adapters.

Lazy-load adapters at package boundaries and fail fast with install hints when extras are missing.

Co-authored-by: Cursor <[email protected]>

tests/unit/optional_dependencies_test.py

@@ -0,0 +1,95 @@
+"""Tests for optional dependency import behavior."""
+
+from __future__ import annotations
+
+import builtins
+import importlib
+import sys
+from collections.abc import Callable, Mapping, Sequence
+from types import ModuleType
+from unittest.mock import patch
+
+import pytest
+
+import python_repositories
+from python_repositories import JsonRepositoryInterface
+
+
+def _block_backend_import(blocked_prefix: str) -> Callable[..., ModuleType]:
+    real_import = builtins.__import__
+
+    def fake_import(
+        name: str,
+        globals: Mapping[str, object] | None = None,
+        locals: Mapping[str, object] | None = None,
+        fromlist: Sequence[str] = (),
+        level: int = 0,
+    ) -> ModuleType:
+        if name == blocked_prefix or name.startswith(f"{blocked_prefix}."):
+            raise ImportError(f"No module named '{name}'")
+        return real_import(name, globals, locals, fromlist, level)
+
+    return fake_import
+
+
+def test_base_import_does_not_load_adapters() -> None:
+    """Interfaces are available without loading adapter modules."""
+    assert JsonRepositoryInterface is not None
+    assert "python_repositories.adapters.redis_adapter" not in sys.modules
+    assert "python_repositories.adapters.minio_adapter" not in sys.modules
+
+
+def test_lazy_adapter_load_succeeds_when_extra_present() -> None:
+    """Adapters load when their optional dependencies are installed."""
+    from python_repositories import MinioAdapter, RedisAdapter
+
+    assert RedisAdapter.__name__ == "RedisAdapter"
+    assert MinioAdapter.__name__ == "MinioAdapter"
+
+
+def test_redis_adapter_import_error_without_extra() -> None:
+    """Missing redis extra raises ImportError with install hint."""
+    import python_repositories.adapters.redis_adapter as redis_adapter_module
+
+    with patch.object(builtins, "__import__", new=_block_backend_import("redis")):
+        with pytest.raises(ImportError, match=r"python-repositories\[redis\]"):
+            importlib.reload(redis_adapter_module)
+
+    importlib.reload(redis_adapter_module)
+
+
+def test_minio_adapter_import_error_without_extra() -> None:
+    """Missing minio extra raises ImportError with install hint."""
+    import python_repositories.adapters.minio_adapter as minio_adapter_module
+
+    with patch.object(builtins, "__import__", new=_block_backend_import("minio")):
+        with pytest.raises(ImportError, match=r"python-repositories\[minio\]"):
+            importlib.reload(minio_adapter_module)
+
+    importlib.reload(minio_adapter_module)
+
+
+def test_top_level_lazy_import_propagates_redis_import_error() -> None:
+    """Top-level RedisAdapter access surfaces adapter import errors."""
+    with patch(
+        "importlib.import_module",
+        side_effect=ImportError(
+            "Redis support requires the redis extra. "
+            "Install with: pip install python-repositories[redis]"
+        ),
+    ):
+        with pytest.raises(ImportError, match=r"python-repositories\[redis\]"):
+            _ = python_repositories.RedisAdapter
+
+
+def test_top_level_lazy_import_propagates_minio_import_error() -> None:
+    """Top-level MinioAdapter access surfaces adapter import errors."""
+    with patch(
+        "importlib.import_module",
+        side_effect=ImportError(
+            "MinIO support requires the minio extra. "
+            "Install with: pip install python-repositories[minio]"
+        ),
+    ):
+        with pytest.raises(ImportError, match=r"python-repositories\[minio\]"):
+            _ = python_repositories.MinioAdapter