chore: release v2.1.0 [skip ci]

Reviewed-on: LilleVemmelund/python-repositories#57

.cursor/rules/pr-after-first-push.mdc

@@ -0,0 +1,58 @@
+---
+description: After first branch push, provide copy-ready PR title and body
+alwaysApply: true
+---
+
+# PR Title and Comment After First Push
+
+The user creates pull requests manually. After the **first push** of a feature branch to remote in a session, always end your response with a copy-ready PR title and PR comment.
+
+## When to provide it
+
+- After the first successful `git push` (or `git push -u origin <branch>`) for a branch in the current task
+- Do **not** create the PR with `gh pr create` unless explicitly asked
+- On later pushes to the same branch, only repeat if the user asks or the change set meaningfully updates what the PR should say
+
+## PR title
+
+- Use a fitting version-bump prefix when changes touch `python_repositories/`:
+  - `[patch]` or `[fix]` — bug fix
+  - `[minor]` or `[feat]` — new feature
+  - `[major]` or `[breaking]` — breaking change
+- Docs-, CI-, or test-only changes: no prefix required
+- Keep the title concise and descriptive
+
+## PR comment format
+
+Provide two separate fenced code blocks the user can copy directly:
+
+1. **PR title** — single line in a code block
+2. **PR comment** — body with `## Summary` and `## Test plan` sections, checklist items reflecting what was actually run
+
+Example structure:
+
+````
+PR title:
+
+```
+[minor] Short description of the change
+```
+
+PR comment:
+
+```
+## Summary
+
+- Bullet points of what changed and why
+
+## Test plan
+
+- [x] Commands or checks that were run
+```
+````
+
+## Notes
+
+- Match the repo PR template ([`.gitea/PULL_REQUEST_TEMPLATE.md`](.gitea/PULL_REQUEST_TEMPLATE.md))
+- Be accurate: only mark test-plan items done if they were run
+- Keep prose clear; the user copies this verbatim into Gitea

.cursor/rules/test-organization.mdc

@@ -0,0 +1,31 @@
+---
+description: Unit test file naming and placement conventions
+globs: tests/**/*.py
+alwaysApply: false
+---
+
+# Test Organization
+
+Unit tests use a one-to-one mapping between source modules and test files.
+
+## Naming
+
+- `python_repositories/<path>/<module>.py` → `tests/unit/<module>_test.py`
+- Test files must end with `_test.py` (enforced by pre-commit `name-tests-test`)
+
+## Placement
+
+- Add tests to the existing `*_test.py` for the module under test
+- Do not create cross-cutting test files (e.g. `structural_typing_test.py`); colocate with the relevant interface/adapter/config test file
+- Shared fixtures → `tests/conftest.py`
+- Module-specific helper classes → the matching test file
+
+## Examples
+
+```
+json_repository_interface.py  →  tests/unit/json_repository_interface_test.py
+redis_adapter.py              →  tests/unit/redis_adapter_test.py
+redis_config.py               →  tests/unit/redis_config_test.py
+```
+
+Integration tests live under `tests/integration/<backend>/` with the same `_test.py` suffix.

CHANGELOG.md

@@ -7,6 +7,40 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.1.0] - 2026-07-11
+
+### Summary
+Add runtime-checkable Protocol typing to public interfaces
+
+### Changed
+- 1cbcc1c Merge pull request '[minor] Add runtime-checkable Protocol typing to public interfaces' (#57) from cursor/protocol-abc-interfaces into main
+- a0e5c9d Document test organization and add Cursor workflow rules.
+- 44b15cb Move structural typing tests into interface unit test files.
+- f6ee9a3 Add runtime-checkable Protocol typing to all public interfaces.
+- 0829354 Merge pull request 'Add async future note and remove redundant pytest pythonpath' (#56) from cursor/readme-async-and-test-path-cleanup into main
+- a0d509a Format CHANGELOG.md with Prettier.
+- 9b7b15a Document possible async support and drop redundant pytest pythonpath.
+
+## [2.0.5] - 2026-07-10
+
+### Summary
+
+Allow empty payloads in Redis and MinIO adapters
+
+### Changed
+
+- 6d02f32 Merge pull request '[patch] Allow empty payloads in Redis and MinIO adapters' (#55) from cursor/allow-empty-payloads into main
+- 57b396b Allow empty payloads in Redis and MinIO adapters.
+- 093e538 Merge pull request '[chore] Scope integration fixtures per backend subdirectory' (#54) from cursor/scoped-integration-fixtures into main
+- b28ac6e Scope integration fixtures per backend subdirectory.
+- 6c66fe4 Merge pull request 'Add consumer-facing CHANGELOG.md maintained by release CI' (#53) from cursor/consumer-changelog into main
+- 089a128 Format CHANGELOG.md with Prettier
+- 0a5bd39 Add consumer-facing CHANGELOG.md maintained by release CI.
+- 683ee33 Merge pull request '[chore] add repository URL and Python 3.12 packaging metadata' (#52) from cursor/add-packaging-metadata into main
+- 9df5032 Add repository URL and Python 3.12 packaging metadata.
+- 4f6f33f Merge pull request 'Drop types-redis in favor of redis inline types' (#51) from cursor/drop-types-redis into main
+- 10d43ce Drop types-redis in favor of redis inline types.
+
 ## [2.0.4] - 2026-07-10
 
 ### Summary

README.md

@@ -12,8 +12,14 @@ Subclass an adapter in your own repository to add domain-specific methods while
 | **Adapters**     | Technology-specific base classes (`RedisAdapter`, `MinioAdapter`) |
 | **Your project** | Subclass an adapter and add domain methods                        |
 
+Each public interface is a `@runtime_checkable` `Protocol` with `@abstractmethod` members. **Subclass an adapter** when you need connection management and shared behavior — explicit subclasses get runtime instantiation guards and inherited default methods (e.g. `scan_keys`). **Type-annotate against an interface** when you want loose coupling — any object with the right methods satisfies the contract for mypy and `isinstance()` checks, without inheriting from this package.
+
 Connection adapters expose `connect()`, `disconnect()`, and `is_connected()`. The latter verifies backend reachability with a cached health probe (default TTL: 1 second). Subclasses may override `health_check_ttl_seconds`. `connect()` is idempotent: calling it while already connected and healthy is a no-op.
 
+## Future direction
+
+The current API is synchronous. Async repository interfaces and adapters may be added in a future release; existing sync usage would remain supported.
+
 ## Optional dependencies
 
 Repository **interfaces** import with the base package. **Adapters** require the matching extra; importing an adapter without its extra raises `ImportError` with install instructions.
@@ -161,10 +167,21 @@ uv sync --all-extras
 uv run pre-commit install   # once per clone — runs hooks on git commit
 uv run pytest tests/unit/ -v                          # fast, no Docker
 uv run pytest -m "not integration" -v                 # all non-Docker tests
+uv run pytest tests/integration/redis/ -v             # Redis container only
+uv run pytest tests/integration/minio/ -v             # MinIO container only
 uv run pytest -v                                      # full suite (requires Docker)
 ```
 
-Integration tests are marked with `@pytest.mark.integration` and require Docker (testcontainers). Run unit tests alone for quick local feedback.
+Integration tests are marked with `@pytest.mark.integration` and require Docker (testcontainers). Backend-specific markers (`needs_redis`, `needs_minio`) let you run only the containers a test module needs. Run unit tests alone for quick local feedback.
+
+### Test organization
+
+Unit tests live in `tests/unit/` and follow a one-to-one naming convention: `<module>_test.py` tests `python_repositories/<module path>.py`. Examples:
+
+- `json_repository_interface.py` → `tests/unit/json_repository_interface_test.py`
+- `redis_adapter.py` → `tests/unit/redis_adapter_test.py`
+
+Add new tests to the existing file for that module rather than creating cross-cutting test files. Shared fixtures belong in `tests/conftest.py`; module-specific helpers may live in the matching test file.
 
 ### CI base image
 

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "python-repositories"
-version = "2.0.4"
+version = "2.1.0"
 description = "Various python repository interfaces exposed as a python package."
 authors = [
     { name = "Brian Bjarke Jensen", email = "schnitzelen@gmail.com" }
@@ -39,10 +39,11 @@ build-backend = "hatchling.build"
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
-pythonpath = ["."]
 addopts = "--import-mode=importlib"
 markers = [
     "integration: tests requiring Docker containers (deselect with '-m \"not integration\"')",
+    "needs_redis: integration test requiring a Redis container",
+    "needs_minio: integration test requiring a MinIO container",
 ]
 
 [tool.coverage.run]

python_repositories/adapters/minio_adapter.py

@@ -19,7 +19,7 @@ except ImportError as exc:
     ) from exc
 
 
-class MinioAdapter(ObjectRepositoryInterface, ConnectionAwareAdapter):
+class MinioAdapter(ConnectionAwareAdapter, ObjectRepositoryInterface):
     """Minio adapter exposing basic CRUD functionality."""
 
     endpoint_env_var_name: str = "MINIO_ENDPOINT"
@@ -114,12 +114,17 @@ class MinioAdapter(ObjectRepositoryInterface, ConnectionAwareAdapter):
         data: BytesIO,
         content_type: str = "application/octet-stream",
     ) -> None:
-        """Put an object into the Minio bucket."""
+        """Put an object into the Minio bucket.
+
+        Accepts zero-byte ``BytesIO``. A zero-byte object is returned by
+        ``get()`` as an empty buffer, not ``None``. Use ``delete()`` to remove
+        an object entirely.
+        """
         # Check input
         if not isinstance(object_name, str) or len(object_name) == 0:
             raise ValueError("object_name must be a non-empty string")
-        if not isinstance(data, BytesIO) or data.getbuffer().nbytes == 0:
+        if not isinstance(data, BytesIO):
-            raise ValueError("data must be a non-empty BytesIO object")
+            raise ValueError("data must be a BytesIO object")
         if not isinstance(content_type, str) or len(content_type) == 0:
             raise ValueError("content_type must be a non-empty string")
         # Check connection
@@ -143,7 +148,12 @@ class MinioAdapter(ObjectRepositoryInterface, ConnectionAwareAdapter):
         )
 
     def get(self, object_name: str) -> BytesIO | None:
-        """Get an object from the Minio bucket."""
+        """Get an object from the Minio bucket.
+
+        Returns ``None`` when the object does not exist. Returns an empty
+        ``BytesIO`` for a zero-byte object. Use ``value is not None`` to test
+        existence.
+        """
         # Check input
         if not isinstance(object_name, str) or len(object_name) == 0:
             raise ValueError("object_name must be a non-empty string")

python_repositories/adapters/redis_adapter.py

@@ -21,7 +21,7 @@ except ImportError as exc:
     ) from exc
 
 
-class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
+class RedisAdapter(ConnectionAwareAdapter, JsonRepositoryInterface):
     """Redis adapter exposing basic CRUD functionality."""
 
     uri_env_var_name: str = "REDIS_URI"
@@ -91,12 +91,17 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
             return False
 
     def set(self, key: str, data: dict[str, Any]) -> None:
-        """Set a JSON object in Redis."""
+        """Set a JSON object in Redis.
+
+        Accepts any dict, including ``{}``. An empty dict creates a key that
+        ``get()`` returns as ``{}``, not ``None``. Use ``delete()`` to remove a
+        key entirely.
+        """
         # Check input
         if not isinstance(key, str) or len(key) == 0:
             raise ValueError("Key must be a non-empty string")
-        if not isinstance(data, dict) or len(data) == 0:
+        if not isinstance(data, dict):
-            raise ValueError("Data must be a non-empty dictionary")
+            raise ValueError("Data must be a dictionary")
         # Check connection
         self._require_connected()
         assert self._client is not None
@@ -105,7 +110,12 @@ class RedisAdapter(JsonRepositoryInterface, ConnectionAwareAdapter):
         self.logger.debug("Set key", key=key, data_keys=list(data.keys()))
 
     def get(self, key: str) -> dict[str, Any] | None:
-        """Get a JSON object from Redis."""
+        """Get a JSON object from Redis.
+
+        Returns ``None`` if the key is absent. Returns ``{}`` if the key exists
+        with an empty JSON object. Use ``value is not None`` to test existence;
+        avoid truthiness checks (``{}`` is falsy).
+        """
         # Check input
         if not isinstance(key, str) or len(key) == 0:
             raise ValueError("Key must be a non-empty string")

python_repositories/interfaces/connection_aware_interface.py

@@ -1,9 +1,11 @@
-"""Definition of ConnectionAwareInterface abstract base class."""
+"""Definition of ConnectionAwareInterface protocol and abstract base class."""
 
-from abc import ABC, abstractmethod
+from abc import abstractmethod
+from typing import Protocol, runtime_checkable
 
 
-class ConnectionAwareInterface(ABC):
+@runtime_checkable
+class ConnectionAwareInterface(Protocol):
     """Interface that defines connection-related methods."""
 
     @abstractmethod

python_repositories/interfaces/context_aware_interface.py

@@ -1,12 +1,13 @@
-"""Definition of ContextAwareInterface abstract base class."""
+"""Definition of ContextAwareInterface protocol and abstract base class."""
 
 from __future__ import annotations
 
-from abc import ABC, abstractmethod
+from abc import abstractmethod
-from typing import Self
+from typing import Protocol, Self, runtime_checkable
 
 
-class ContextAwareInterface(ABC):
+@runtime_checkable
+class ContextAwareInterface(Protocol):
     """Interface that defines context-related methods."""
 
     @abstractmethod

python_repositories/interfaces/json_repository_interface.py

@@ -1,26 +1,37 @@
-"""Definition of JsonRepositoryInterface abstract base class."""
+"""Definition of JsonRepositoryInterface protocol and abstract base class."""
 
-from abc import ABC, abstractmethod
+from abc import abstractmethod
 from collections.abc import Iterator
-from typing import Any
+from typing import Any, Protocol, runtime_checkable
 
 
-class JsonRepositoryInterface(ABC):
+@runtime_checkable
+class JsonRepositoryInterface(Protocol):
     """Interface that defines JSON document CRUD methods."""
 
     @abstractmethod
     def get(self, key: str) -> dict[str, Any] | None:
-        """Get a JSON object by key."""
+        """Get a JSON object by key.
+
+        Returns ``None`` when the key is absent. Returns ``{}`` when the key
+        exists with an empty JSON object. Use ``value is not None`` to test
+        existence; avoid truthiness checks (``{}`` is falsy).
+        """
         ...
 
     @abstractmethod
     def set(self, key: str, data: dict[str, Any]) -> None:
-        """Set a JSON object by key."""
+        """Set a JSON object by key.
+
+        Accepts any dict, including ``{}``. An empty dict creates a key that
+        ``get()`` returns as ``{}``, not ``None``. Use ``delete()`` to remove a
+        key entirely.
+        """
         ...
 
     @abstractmethod
     def delete(self, key: str) -> None:
-        """Delete a JSON object by key."""
+        """Delete a JSON object by key, removing it entirely."""
         ...
 
     @abstractmethod

python_repositories/interfaces/object_repository_interface.py

@@ -1,18 +1,22 @@
-"""Definition of ObjectRepositoryInterface abstract base class."""
+"""Definition of ObjectRepositoryInterface protocol and abstract base class."""
 
-from abc import ABC, abstractmethod
+from abc import abstractmethod
 from io import BytesIO
+from typing import Protocol, runtime_checkable
 
 
-class ObjectRepositoryInterface(ABC):
+@runtime_checkable
+class ObjectRepositoryInterface(Protocol):
     """Interface that defines binary object CRUD methods."""
 
     @abstractmethod
     def get(self, object_name: str) -> BytesIO | None:
         """Get an object by name.
 
-        Returns None when the object does not exist. Raises ConnectionError when
+        Returns ``None`` when the object does not exist. Returns an empty
-        not connected. Other backend errors propagate to the caller.
+        ``BytesIO`` for a zero-byte object. Use ``value is not None`` to test
+        existence. Raises ConnectionError when not connected. Other backend
+        errors propagate to the caller.
         """
         ...
 
@@ -23,12 +27,17 @@ class ObjectRepositoryInterface(ABC):
         data: BytesIO,
         content_type: str = "application/octet-stream",
     ) -> None:
-        """Put an object by name."""
+        """Put an object by name.
+
+        Accepts zero-byte ``BytesIO``. A zero-byte object is returned by
+        ``get()`` as an empty buffer, not ``None``. Use ``delete()`` to remove
+        an object entirely.
+        """
         ...
 
     @abstractmethod
     def delete(self, object_name: str) -> None:
-        """Delete an object by name."""
+        """Delete an object by name, removing it entirely."""
         ...
 
     @abstractmethod

tests/integration/conftest.py

@@ -1,51 +1,9 @@
 """Integration tests configuration."""
 
-from collections.abc import Generator
 import logging
-from typing import Any, cast
 
-from minio import Minio
 import pytest
-import redis
 import structlog
-from testcontainers.core.container import DockerContainer
-from testcontainers.core.waiting_utils import WaitStrategy, WaitStrategyTarget
-from testcontainers.minio import MinioContainer
-
-from python_repositories.config import MinioConfig, RedisConfig
-
-REDIS_PORT = 6379
-
-MINIO_ACCESS_KEY = "minioadmin"
-MINIO_SECRET_KEY = "minioadmin"
-MINIO_BUCKET = "test-bucket"
-
-
-class _RedisPingWaitStrategy(WaitStrategy):
-    def __init__(self) -> None:
-        super().__init__()
-        self.with_transient_exceptions(redis.exceptions.ConnectionError)
-
-    def wait_until_ready(self, container: WaitStrategyTarget) -> None:
-        redis_container = cast("RedisTestContainer", container)
-        if not self._poll(lambda: redis_container.get_client().ping()):
-            raise redis.exceptions.ConnectionError("Could not connect to Redis")
-
-
-class RedisTestContainer(DockerContainer):
-    """Redis container using wait strategies instead of the deprecated decorator."""
-
-    def __init__(self, image: str, port: int = REDIS_PORT) -> None:
-        super().__init__(image, _wait_strategy=_RedisPingWaitStrategy())
-        self.port = port
-        self.with_exposed_ports(self.port)
-
-    def get_client(self, **kwargs: Any) -> redis.Redis:
-        return redis.Redis(
-            host=self.get_container_host_ip(),
-            port=self.get_exposed_port(self.port),
-            **kwargs,
-        )
 
 
 @pytest.fixture(scope="session", autouse=True)
@@ -64,96 +22,3 @@ def configure_logging() -> None:
         cache_logger_on_first_use=True,
     )
     logging.basicConfig(level=logging.ERROR)
-
-
-@pytest.fixture(scope="session")
-def redis_container() -> Generator[str, None, None]:
-    """Set up a Redis container for testing and yield the Redis URI."""
-    container = RedisTestContainer(
-        image="redis/redis-stack:7.2.0-v0",
-    )
-    container.start()
-    redis_host = container.get_container_host_ip()
-    redis_port = container.get_exposed_port(REDIS_PORT)
-    redis_uri = f"redis://{redis_host}:{redis_port}"
-
-    yield redis_uri
-
-    container.stop()
-
-
-@pytest.fixture(scope="session")
-def minio_container() -> Generator[dict[str, str], None, None]:
-    """Set up a Minio container for testing and yield connection settings."""
-    container = MinioContainer(
-        image="minio/minio:latest",
-        access_key=MINIO_ACCESS_KEY,
-        secret_key=MINIO_SECRET_KEY,
-    )
-    container.start()
-    minio_host = container.get_container_host_ip()
-    minio_port = container.get_exposed_port(9000)
-    minio_endpoint = f"{minio_host}:{minio_port}"
-    env_vars = {
-        "MINIO_ENDPOINT": minio_endpoint,
-        "MINIO_ACCESS_KEY": MINIO_ACCESS_KEY,
-        "MINIO_SECRET_KEY": MINIO_SECRET_KEY,
-        "MINIO_BUCKET": MINIO_BUCKET,
-        "MINIO_SECURE": "false",
-    }
-
-    yield env_vars
-
-    container.stop()
-
-
-@pytest.fixture(scope="session")
-def redis_config(redis_container: str) -> RedisConfig:
-    """Provide RedisConfig built from the test container."""
-    return RedisConfig(uri=redis_container)
-
-
-@pytest.fixture(scope="session")
-def minio_config(minio_container: dict[str, str]) -> MinioConfig:
-    """Provide MinioConfig built from the test container."""
-    return MinioConfig(
-        endpoint=minio_container["MINIO_ENDPOINT"],
-        access_key=minio_container["MINIO_ACCESS_KEY"],
-        secret_key=minio_container["MINIO_SECRET_KEY"],
-        bucket=minio_container["MINIO_BUCKET"],
-        secure=False,
-    )
-
-
-@pytest.fixture(scope="session")
-def raw_redis_client(redis_container: str) -> Generator[redis.Redis, None, None]:
-    """Provide a raw Redis client connected to the test Redis container."""
-    client = redis.Redis.from_url(
-        url=redis_container,
-        socket_connect_timeout=10,
-    )
-
-    yield client
-
-    client.flushall()
-    client.close()
-
-
-@pytest.fixture(scope="session")
-def raw_minio_client(minio_container: dict[str, str]) -> Generator[Minio, None, None]:
-    """Provide a raw Minio client connected to the test Minio container."""
-    client = Minio(
-        endpoint=minio_container["MINIO_ENDPOINT"],
-        access_key=minio_container["MINIO_ACCESS_KEY"],
-        secret_key=minio_container["MINIO_SECRET_KEY"],
-        secure=False,
-    )
-    bucket_name = minio_container["MINIO_BUCKET"]
-    if not client.bucket_exists(bucket_name):
-        client.make_bucket(bucket_name)
-
-    yield client
-
-    objects = client.list_objects(bucket_name, recursive=True)
-    for obj in objects:
-        client.remove_object(bucket_name, obj.object_name)

tests/integration/examples/conftest.py

@@ -0,0 +1,55 @@
+"""Examples integration test fixtures."""
+
+from collections.abc import Generator
+
+from minio import Minio
+import pytest
+import redis
+
+from python_repositories.config import MinioConfig, RedisConfig
+from tests.integration.minio._containers import (
+    minio_config_from_env,
+    minio_env,
+    raw_minio_client_from_env,
+)
+from tests.integration.redis._containers import (
+    raw_redis_client_from_container,
+    redis_config_from_container,
+    redis_uri,
+)
+
+
+@pytest.fixture(scope="session")
+def redis_container() -> Generator[str, None, None]:
+    """Set up a Redis container for testing and yield the Redis URI."""
+    yield from redis_uri()
+
+
+@pytest.fixture(scope="session")
+def redis_config(redis_container: str) -> RedisConfig:
+    """Provide RedisConfig built from the test container."""
+    return redis_config_from_container(redis_container)
+
+
+@pytest.fixture(scope="session")
+def raw_redis_client(redis_container: str) -> Generator[redis.Redis, None, None]:
+    """Provide a raw Redis client connected to the test Redis container."""
+    yield from raw_redis_client_from_container(redis_container)
+
+
+@pytest.fixture(scope="session")
+def minio_container() -> Generator[dict[str, str], None, None]:
+    """Set up a Minio container for testing and yield connection settings."""
+    yield from minio_env()
+
+
+@pytest.fixture(scope="session")
+def minio_config(minio_container: dict[str, str]) -> MinioConfig:
+    """Provide MinioConfig built from the test container."""
+    return minio_config_from_env(minio_container)
+
+
+@pytest.fixture(scope="session")
+def raw_minio_client(minio_container: dict[str, str]) -> Generator[Minio, None, None]:
+    """Provide a raw Minio client connected to the test Minio container."""
+    yield from raw_minio_client_from_env(minio_container)

tests/integration/examples/examples_test.py

@@ -13,7 +13,11 @@ from python_repositories.examples.artifact_object_repository import (
 )
 from python_repositories.examples.user_json_repository import UserJsonRepository
 
-pytestmark = pytest.mark.integration
+pytestmark = [
+    pytest.mark.integration,
+    pytest.mark.needs_redis,
+    pytest.mark.needs_minio,
+]
 
 
 @pytest.fixture(scope="module", autouse=True)

tests/integration/minio/_containers.py

@@ -0,0 +1,86 @@
+"""MinIO container session helpers for integration tests."""
+
+from collections.abc import Generator
+
+from minio import Minio
+from testcontainers.minio import MinioContainer
+
+from python_repositories.config import MinioConfig
+
+MINIO_ACCESS_KEY = "minioadmin"
+MINIO_SECRET_KEY = "minioadmin"
+MINIO_BUCKET = "test-bucket"
+
+_minio_env: dict[str, str] | None = None
+_minio_container: MinioContainer | None = None
+_raw_minio_client: Minio | None = None
+_minio_env_refs = 0
+_raw_minio_client_refs = 0
+
+
+def minio_env() -> Generator[dict[str, str], None, None]:
+    """Yield session-scoped MinIO connection settings, starting the container once."""
+    global _minio_env, _minio_container, _minio_env_refs
+    if _minio_env is None:
+        _minio_container = MinioContainer(
+            image="minio/minio:latest",
+            access_key=MINIO_ACCESS_KEY,
+            secret_key=MINIO_SECRET_KEY,
+        )
+        _minio_container.start()
+        minio_host = _minio_container.get_container_host_ip()
+        minio_port = _minio_container.get_exposed_port(9000)
+        minio_endpoint = f"{minio_host}:{minio_port}"
+        _minio_env = {
+            "MINIO_ENDPOINT": minio_endpoint,
+            "MINIO_ACCESS_KEY": MINIO_ACCESS_KEY,
+            "MINIO_SECRET_KEY": MINIO_SECRET_KEY,
+            "MINIO_BUCKET": MINIO_BUCKET,
+            "MINIO_SECURE": "false",
+        }
+
+    _minio_env_refs += 1
+    yield _minio_env
+    _minio_env_refs -= 1
+
+    if _minio_env_refs == 0 and _minio_container is not None:
+        _minio_container.stop()
+        _minio_container = None
+        _minio_env = None
+
+
+def minio_config_from_env(env: dict[str, str]) -> MinioConfig:
+    """Build MinioConfig from container environment settings."""
+    return MinioConfig(
+        endpoint=env["MINIO_ENDPOINT"],
+        access_key=env["MINIO_ACCESS_KEY"],
+        secret_key=env["MINIO_SECRET_KEY"],
+        bucket=env["MINIO_BUCKET"],
+        secure=False,
+    )
+
+
+def raw_minio_client_from_env(env: dict[str, str]) -> Generator[Minio, None, None]:
+    """Yield a session-scoped raw MinIO client, reusing one client per session."""
+    global _raw_minio_client, _raw_minio_client_refs
+    if _raw_minio_client is None:
+        _raw_minio_client = Minio(
+            endpoint=env["MINIO_ENDPOINT"],
+            access_key=env["MINIO_ACCESS_KEY"],
+            secret_key=env["MINIO_SECRET_KEY"],
+            secure=False,
+        )
+        bucket_name = env["MINIO_BUCKET"]
+        if not _raw_minio_client.bucket_exists(bucket_name):
+            _raw_minio_client.make_bucket(bucket_name)
+
+    _raw_minio_client_refs += 1
+    yield _raw_minio_client
+    _raw_minio_client_refs -= 1
+
+    if _raw_minio_client_refs == 0 and _raw_minio_client is not None:
+        bucket_name = env["MINIO_BUCKET"]
+        objects = _raw_minio_client.list_objects(bucket_name, recursive=True)
+        for obj in objects:
+            _raw_minio_client.remove_object(bucket_name, obj.object_name)
+        _raw_minio_client = None

tests/integration/minio/conftest.py

@@ -0,0 +1,31 @@
+"""MinIO integration test fixtures."""
+
+from collections.abc import Generator
+
+from minio import Minio
+import pytest
+
+from python_repositories.config import MinioConfig
+from tests.integration.minio._containers import (
+    minio_config_from_env,
+    minio_env,
+    raw_minio_client_from_env,
+)
+
+
+@pytest.fixture(scope="session")
+def minio_container() -> Generator[dict[str, str], None, None]:
+    """Set up a Minio container for testing and yield connection settings."""
+    yield from minio_env()
+
+
+@pytest.fixture(scope="session")
+def minio_config(minio_container: dict[str, str]) -> MinioConfig:
+    """Provide MinioConfig built from the test container."""
+    return minio_config_from_env(minio_container)
+
+
+@pytest.fixture(scope="session")
+def raw_minio_client(minio_container: dict[str, str]) -> Generator[Minio, None, None]:
+    """Provide a raw Minio client connected to the test Minio container."""
+    yield from raw_minio_client_from_env(minio_container)

tests/integration/minio/minio_adapter_test.py

@@ -15,7 +15,7 @@ from python_repositories.adapters.minio_adapter import MinioAdapter
 from python_repositories.config import MinioConfig
 from tests.conftest import TEST_MINIO_CONFIG
 
-pytestmark = pytest.mark.integration
+pytestmark = [pytest.mark.integration, pytest.mark.needs_minio]
 
 
 def same_data(
@@ -328,6 +328,44 @@ def test_should_raise_value_error_on_invalid_put_data(
             minio_adapter.put(object_name, invalid)  # type: ignore
 
 
+def test_should_put_and_get_empty_bytesio(
+    minio_adapter: MinioAdapter,
+    minio_config: MinioConfig,
+) -> None:
+    """Test that the MinioAdapter can put and get a zero-byte object."""
+    object_name = "empty_object"
+    empty_data = BytesIO()
+    assert minio_adapter.get(object_name) is None
+    minio_adapter.put(object_name, empty_data)
+    received_data = minio_adapter.get(object_name)
+    assert received_data is not None
+    assert same_data(empty_data, received_data)
+    minio_adapter._client.remove_object(minio_config.bucket, object_name)  # type: ignore[union-attr]
+
+
+def test_should_distinguish_missing_object_from_empty_object(
+    minio_adapter: MinioAdapter,
+    minio_config: MinioConfig,
+) -> None:
+    """Test that missing objects and zero-byte objects are distinguishable."""
+    object_name = "empty_object"
+    minio_adapter.put(object_name, BytesIO())
+    assert minio_adapter.get("other_object") is None
+    minio_adapter.delete(object_name)
+    assert minio_adapter.get(object_name) is None
+
+
+def test_should_list_zero_byte_object(
+    minio_adapter: MinioAdapter,
+    minio_config: MinioConfig,
+) -> None:
+    """Test that a zero-byte object appears in object listings."""
+    object_name = "empty_object"
+    minio_adapter.put(object_name, BytesIO())
+    assert object_name in minio_adapter.list_objects()
+    minio_adapter._client.remove_object(minio_config.bucket, object_name)  # type: ignore[union-attr]
+
+
 def test_should_raise_value_error_on_invalid_put_content_type(
     data: BytesIO,
     minio_adapter: MinioAdapter,

tests/integration/redis/_containers.py

@@ -0,0 +1,90 @@
+"""Redis container session helpers for integration tests."""
+
+from collections.abc import Generator
+from typing import Any, cast
+
+import redis
+from testcontainers.core.container import DockerContainer
+from testcontainers.core.waiting_utils import WaitStrategy, WaitStrategyTarget
+
+from python_repositories.config import RedisConfig
+
+REDIS_PORT = 6379
+
+
+class _RedisPingWaitStrategy(WaitStrategy):
+    def __init__(self) -> None:
+        super().__init__()
+        self.with_transient_exceptions(redis.exceptions.ConnectionError)
+
+    def wait_until_ready(self, container: WaitStrategyTarget) -> None:
+        redis_container = cast("RedisTestContainer", container)
+        if not self._poll(lambda: redis_container.get_client().ping()):
+            raise redis.exceptions.ConnectionError("Could not connect to Redis")
+
+
+class RedisTestContainer(DockerContainer):
+    """Redis container using wait strategies instead of the deprecated decorator."""
+
+    def __init__(self, image: str, port: int = REDIS_PORT) -> None:
+        super().__init__(image, _wait_strategy=_RedisPingWaitStrategy())
+        self.port = port
+        self.with_exposed_ports(self.port)
+
+    def get_client(self, **kwargs: Any) -> redis.Redis:
+        return redis.Redis(
+            host=self.get_container_host_ip(),
+            port=self.get_exposed_port(self.port),
+            **kwargs,
+        )
+
+
+_redis_uri: str | None = None
+_redis_container: RedisTestContainer | None = None
+_raw_redis_client: redis.Redis | None = None
+_redis_uri_refs = 0
+_raw_redis_client_refs = 0
+
+
+def redis_uri() -> Generator[str, None, None]:
+    """Yield a session-scoped Redis URI, starting the container once."""
+    global _redis_uri, _redis_container, _redis_uri_refs
+    if _redis_uri is None:
+        _redis_container = RedisTestContainer(image="redis/redis-stack:7.2.0-v0")
+        _redis_container.start()
+        redis_host = _redis_container.get_container_host_ip()
+        redis_port = _redis_container.get_exposed_port(REDIS_PORT)
+        _redis_uri = f"redis://{redis_host}:{redis_port}"
+
+    _redis_uri_refs += 1
+    yield _redis_uri
+    _redis_uri_refs -= 1
+
+    if _redis_uri_refs == 0 and _redis_container is not None:
+        _redis_container.stop()
+        _redis_container = None
+        _redis_uri = None
+
+
+def redis_config_from_container(uri: str) -> RedisConfig:
+    """Build RedisConfig from a container URI."""
+    return RedisConfig(uri=uri)
+
+
+def raw_redis_client_from_container(uri: str) -> Generator[redis.Redis, None, None]:
+    """Yield a session-scoped raw Redis client, reusing one client per session."""
+    global _raw_redis_client, _raw_redis_client_refs
+    if _raw_redis_client is None:
+        _raw_redis_client = redis.Redis.from_url(
+            url=uri,
+            socket_connect_timeout=10,
+        )
+
+    _raw_redis_client_refs += 1
+    yield _raw_redis_client
+    _raw_redis_client_refs -= 1
+
+    if _raw_redis_client_refs == 0 and _raw_redis_client is not None:
+        _raw_redis_client.flushall()
+        _raw_redis_client.close()
+        _raw_redis_client = None

tests/integration/redis/conftest.py

@@ -0,0 +1,31 @@
+"""Redis integration test fixtures."""
+
+from collections.abc import Generator
+
+import pytest
+import redis
+
+from python_repositories.config import RedisConfig
+from tests.integration.redis._containers import (
+    raw_redis_client_from_container,
+    redis_config_from_container,
+    redis_uri,
+)
+
+
+@pytest.fixture(scope="session")
+def redis_container() -> Generator[str, None, None]:
+    """Set up a Redis container for testing and yield the Redis URI."""
+    yield from redis_uri()
+
+
+@pytest.fixture(scope="session")
+def redis_config(redis_container: str) -> RedisConfig:
+    """Provide RedisConfig built from the test container."""
+    return redis_config_from_container(redis_container)
+
+
+@pytest.fixture(scope="session")
+def raw_redis_client(redis_container: str) -> Generator[redis.Redis, None, None]:
+    """Provide a raw Redis client connected to the test Redis container."""
+    yield from raw_redis_client_from_container(redis_container)

tests/integration/redis/redis_adapter_test.py

@@ -10,7 +10,7 @@ from redis.commands.json.path import Path as RedisPath
 from python_repositories.adapters.redis_adapter import RedisAdapter
 from python_repositories.config import RedisConfig
 
-pytestmark = pytest.mark.integration
+pytestmark = [pytest.mark.integration, pytest.mark.needs_redis]
 
 
 @pytest.fixture(scope="module")
@@ -190,12 +190,45 @@ def test_should_raise_value_error_on_invalid_set_data(
 ) -> None:
     """Test that the RedisAdapter raises ValueError when setting with invalid data."""
     key = "test_key"
-    invalid_data = ["", 123, None, [], {}]
+    invalid_data = ["", 123, None, []]
     for data in invalid_data:
         with pytest.raises(ValueError):
             redis_adapter.set(key, data)  # type: ignore
 
 
+def test_should_set_and_get_empty_dict(
+    redis_adapter: RedisAdapter,
+) -> None:
+    """Test that the RedisAdapter can set and get an empty dict."""
+    key = "empty_key"
+    assert redis_adapter.get(key) is None
+    redis_adapter.set(key, {})
+    value = redis_adapter.get(key)
+    assert value is not None
+    assert value == {}
+
+
+def test_should_distinguish_missing_key_from_empty_dict(
+    redis_adapter: RedisAdapter,
+) -> None:
+    """Test that missing keys and empty dicts are distinguishable."""
+    key = "empty_key"
+    redis_adapter.set(key, {})
+    assert redis_adapter.get("other_key") is None
+    redis_adapter.delete(key)
+    assert redis_adapter.get(key) is None
+
+
+def test_should_list_empty_dict_key(
+    redis_adapter: RedisAdapter,
+) -> None:
+    """Test that a key with an empty dict appears in key listings."""
+    key = "empty_key"
+    redis_adapter.set(key, {})
+    assert key in redis_adapter.list_keys(key)
+    assert key in list(redis_adapter.scan_keys(key))
+
+
 def test_should_raise_connection_error_on_set_when_not_connected(
     redis_config: RedisConfig,
     data: dict[str, str],

tests/unit/connection_aware_interface_test.py

@@ -7,6 +7,24 @@ from python_repositories.interfaces.connection_aware_interface import (
 )
 
 
+class FakeConnection:
+    """Plain class that satisfies ConnectionAwareInterface without inheritance."""
+
+    def connect(self) -> None:
+        pass
+
+    def disconnect(self) -> None:
+        pass
+
+    def is_connected(self) -> bool:
+        return True
+
+
+def accepts_connection_aware(connection: ConnectionAwareInterface) -> None:
+    """Type-checking hook for ConnectionAwareInterface structural subtyping."""
+    connection.is_connected()
+
+
 def test_instantiation_fails_when_connect_not_implemented() -> None:
     """Test that instantiation fails if connect is not implemented."""
 
@@ -53,3 +71,10 @@ def test_instantiation_fails_when_is_connected_not_implemented() -> None:
 
     with pytest.raises(TypeError):
         _ = Incomplete()  # type: ignore
+
+
+def test_structural_subtyping() -> None:
+    """Test that a plain class satisfies ConnectionAwareInterface structurally."""
+    connection: ConnectionAwareInterface = FakeConnection()
+    accepts_connection_aware(connection)
+    assert isinstance(connection, ConnectionAwareInterface)

tests/unit/context_aware_interface_test.py

@@ -7,6 +7,24 @@ import pytest
 from python_repositories.interfaces.context_aware_interface import ContextAwareInterface
 
 
+class FakeContextManager:
+    """Plain class that satisfies ContextAwareInterface without inheritance."""
+
+    def __enter__(self) -> FakeContextManager:
+        return self
+
+    def __exit__(
+        self, exc_type: type | None, exc_val: object | None, exc_tb: object | None
+    ) -> None:
+        pass
+
+
+def accepts_context_aware(context: ContextAwareInterface) -> None:
+    """Type-checking hook for ContextAwareInterface structural subtyping."""
+    with context:
+        pass
+
+
 def test_instantiation_fails_when_enter_not_implemented() -> None:
     """Test that instantiation fails if __enter__ is not implemented."""
 
@@ -33,3 +51,10 @@ def test_instantiation_fails_when_exit_not_implemented() -> None:
 
     with pytest.raises(TypeError):
         _ = Incomplete()  # type: ignore
+
+
+def test_structural_subtyping() -> None:
+    """Test that a plain class satisfies ContextAwareInterface structurally."""
+    context: ContextAwareInterface = FakeContextManager()
+    accepts_context_aware(context)
+    assert isinstance(context, ContextAwareInterface)

tests/unit/json_repository_interface_test.py

@@ -1,5 +1,6 @@
 """Unit tests for JsonRepositoryInterface."""
 
+from collections.abc import Iterator
 from typing import Any
 
 import pytest
@@ -9,6 +10,36 @@ from python_repositories.interfaces.json_repository_interface import (
 )
 
 
+class InMemoryJsonRepo:
+    """Plain class that satisfies JsonRepositoryInterface without inheritance."""
+
+    def get(self, key: str) -> dict[str, Any] | None:
+        return None
+
+    def set(self, key: str, data: dict[str, Any]) -> None:
+        pass
+
+    def delete(self, key: str) -> None:
+        pass
+
+    def list_keys(self, pattern: str) -> list[str]:
+        return []
+
+    def scan_keys(
+        self,
+        pattern: str,
+        *,
+        count: int | None = None,
+    ) -> Iterator[str]:
+        del count
+        yield from self.list_keys(pattern)
+
+
+def accepts_json_repo(repo: JsonRepositoryInterface) -> None:
+    """Type-checking hook for JsonRepositoryInterface structural subtyping."""
+    repo.get("key")
+
+
 def test_instantiation_fails_when_get_not_implemented() -> None:
     """Test that instantiation fails if get is not implemented."""
 
@@ -104,3 +135,10 @@ def test_scan_keys_defaults_to_list_keys() -> None:
     repository = Complete()
 
     assert list(repository.scan_keys("user")) == ["user-1", "user-2"]
+
+
+def test_structural_subtyping() -> None:
+    """Test that a plain class satisfies JsonRepositoryInterface structurally."""
+    repo: JsonRepositoryInterface = InMemoryJsonRepo()
+    accepts_json_repo(repo)
+    assert isinstance(repo, JsonRepositoryInterface)

tests/unit/object_repository_interface_test.py

@@ -9,6 +9,32 @@ from python_repositories.interfaces.object_repository_interface import (
 )
 
 
+class InMemoryObjectRepo:
+    """Plain class that satisfies ObjectRepositoryInterface without inheritance."""
+
+    def get(self, object_name: str) -> BytesIO | None:
+        return None
+
+    def put(
+        self,
+        object_name: str,
+        data: BytesIO,
+        content_type: str = "application/octet-stream",
+    ) -> None:
+        pass
+
+    def delete(self, object_name: str) -> None:
+        pass
+
+    def list_objects(self, prefix: str = "") -> list[str]:
+        return []
+
+
+def accepts_object_repo(repo: ObjectRepositoryInterface) -> None:
+    """Type-checking hook for ObjectRepositoryInterface structural subtyping."""
+    repo.get("object")
+
+
 def test_instantiation_fails_when_get_not_implemented() -> None:
     """Test that instantiation fails if get is not implemented."""
 
@@ -98,3 +124,10 @@ def test_instantiation_fails_when_list_objects_not_implemented() -> None:
 
     with pytest.raises(TypeError):
         _ = Incomplete()  # type: ignore
+
+
+def test_structural_subtyping() -> None:
+    """Test that a plain class satisfies ObjectRepositoryInterface structurally."""
+    repo: ObjectRepositoryInterface = InMemoryObjectRepo()
+    accepts_object_repo(repo)
+    assert isinstance(repo, ObjectRepositoryInterface)

uv.lock

@@ -1,5 +1,5 @@
 version = 1
-revision = 3
+revision = 2
 requires-python = ">=3.12"
 resolution-markers = [
     "python_full_version >= '3.15'",
@@ -1056,7 +1056,7 @@ wheels = [
 
 [[package]]
 name = "python-repositories"
-version = "2.0.4"
+version = "2.1.0"
 source = { editable = "." }
 dependencies = [
     { name = "python-dotenv" },