feat: add dependency_overrides parameter to create_async_client (#61)

src/fastapi_toolsets/pytest/utils.py

@@ -1,7 +1,7 @@
 """Pytest helper utilities for FastAPI testing."""
 
 import os
-from collections.abc import AsyncGenerator
+from collections.abc import AsyncGenerator, Callable
 from contextlib import asynccontextmanager
 from typing import Any
 
@@ -22,12 +22,16 @@ from ..db import create_db_context
 async def create_async_client(
     app: Any,
     base_url: str = "http://test",
+    dependency_overrides: dict[Callable[..., Any], Callable[..., Any]] | None = None,
 ) -> AsyncGenerator[AsyncClient, None]:
     """Create an async httpx client for testing FastAPI applications.
 
     Args:
         app: FastAPI application instance.
         base_url: Base URL for requests. Defaults to "http://test".
+        dependency_overrides: Optional mapping of original dependencies to
+            their test replacements. Applied via ``app.dependency_overrides``
+            before yielding and cleaned up after.
 
     Yields:
         An AsyncClient configured for the app.
@@ -46,10 +50,37 @@ async def create_async_client(
         async def test_endpoint(client: AsyncClient):
             response = await client.get("/health")
             assert response.status_code == 200
+
+    Example with dependency overrides:
+        from fastapi_toolsets.pytest import create_async_client, create_db_session
+        from app.db import get_db
+
+        @pytest.fixture
+        async def db_session():
+            async with create_db_session(DATABASE_URL, Base, cleanup=True) as session:
+                yield session
+
+        @pytest.fixture
+        async def client(db_session):
+            async def override():
+                yield db_session
+
+            async with create_async_client(
+                app, dependency_overrides={get_db: override}
+            ) as c:
+                yield c
     """
+    if dependency_overrides:
+        app.dependency_overrides.update(dependency_overrides)
+
     transport = ASGITransport(app=app)
-    async with AsyncClient(transport=transport, base_url=base_url) as client:
-        yield client
+    try:
+        async with AsyncClient(transport=transport, base_url=base_url) as client:
+            yield client
+    finally:
+        if dependency_overrides:
+            for key in dependency_overrides:
+                app.dependency_overrides.pop(key, None)
 
 
 @asynccontextmanager

tests/test_pytest.py

@@ -3,7 +3,7 @@
 import uuid
 
 import pytest
-from fastapi import FastAPI
+from fastapi import Depends, FastAPI
 from httpx import AsyncClient
 from sqlalchemy import select, text
 from sqlalchemy.engine import make_url
@@ -236,6 +236,30 @@ class TestCreateAsyncClient:
 
         assert client_ref.is_closed
 
+    @pytest.mark.anyio
+    async def test_dependency_overrides_applied_and_cleaned(self):
+        """Dependency overrides are applied during the context and removed after."""
+        app = FastAPI()
+
+        async def original_dep() -> str:
+            return "original"
+
+        async def override_dep() -> str:
+            return "overridden"
+
+        @app.get("/dep")
+        async def dep_endpoint(value: str = Depends(original_dep)):
+            return {"value": value}
+
+        async with create_async_client(
+            app, dependency_overrides={original_dep: override_dep}
+        ) as client:
+            response = await client.get("/dep")
+            assert response.json() == {"value": "overridden"}
+
+        # Overrides should be cleaned up
+        assert original_dep not in app.dependency_overrides
+
 
 class TestCreateDbSession:
     """Tests for create_db_session helper."""