✨ Add support for Trio via AnyIO

docs/en/docs/advanced/async-tests.md

@@ -6,21 +6,9 @@ Being able to use asynchronous functions in your tests could be useful, for exam
 
 Let's look at how we can make that work.
 
-## pytest-asyncio
+## pytest.mark.anyio
 
-If we want to call asynchronous functions in our tests, our test functions have to be asynchronous. Pytest provides a neat library for this, called `pytest-asyncio`, that allows us to specify that some test functions are to be called asynchronously.
-
-You can install it via:
-
-<div class="termy">
-
-```console
-$ pip install pytest-asyncio
-
----> 100%
-```
-
-</div>
+If we want to call asynchronous functions in our tests, our test functions have to be asynchronous. Anyio provides a neat plugin for this, that allows us to specify that some test functions are to be called asynchronously.
 
 ## HTTPX
 
@@ -66,7 +54,7 @@ $ pytest
 
 ## In Detail
 
-The marker `@pytest.mark.asyncio` tells pytest that this test function should be called asynchronously:
+The marker `@pytest.mark.anyio` tells pytest that this test function should be called asynchronously:
 
 ```Python hl_lines="7"
 {!../../../docs_src/async_tests/test_main.py!}
@@ -97,4 +85,4 @@ that we used to make our requests with the `TestClient`.
 As the testing function is now asynchronous, you can now also call (and `await`) other `async` functions apart from sending requests to your FastAPI application in your tests, exactly as you would call them anywhere else in your code.
 
 !!! tip
-    If you encounter a `RuntimeError: Task attached to a different loop` when integrating asynchronous function calls in your tests (e.g. when using <a href="https://stackoverflow.com/questions/41584243/runtimeerror-task-attached-to-a-different-loop" class="external-link" target="_blank">MongoDB's MotorClient</a>) check out <a href="https://github.com/pytest-dev/pytest-asyncio/issues/38#issuecomment-264418154" class="external-link" target="_blank">this issue</a> in the pytest-asyncio repository.
+    If you encounter a `RuntimeError: Task attached to a different loop` when integrating asynchronous function calls in your tests (e.g. when using <a href="https://stackoverflow.com/questions/41584243/runtimeerror-task-attached-to-a-different-loop" class="external-link" target="_blank">MongoDB's MotorClient</a>) Remember to instantiate objects that need an event loop only within async functions, eg an `'@app.on_event("startup")` callback.

docs_src/async_tests/test_main.py

@@ -4,7 +4,7 @@
 from .main import app
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_root():
     async with AsyncClient(app=app, base_url="http://test") as ac:
         response = await ac.get("/")

docs_src/custom_response/tutorial008.py

@@ -7,5 +7,8 @@
 
 @app.get("/")
 def main():
-    file_like = open(some_file_path, mode="rb")
-    return StreamingResponse(file_like, media_type="video/mp4")
+    def iterfile():
+        with open(some_file_path, mode="rb") as file_like:
+            yield from file_like
+
+    return StreamingResponse(iterfile(), media_type="video/mp4")

fastapi/dependencies/utils.py

@@ -1,21 +1,23 @@
-import asyncio
 import inspect
 from contextlib import contextmanager
 from copy import deepcopy
 from typing import (
     Any,
     Callable,
+    Coroutine,
     Dict,
     List,
     Mapping,
     Optional,
     Sequence,
     Tuple,
     Type,
+    TypeVar,
     Union,
     cast,
 )
 
+import anyio
 from fastapi import params
 from fastapi.concurrency import (
     AsyncExitStack,
@@ -85,6 +87,25 @@
 )
 
 
+_T = TypeVar("_T")
+
+
+async def _run_and_assign(
+    results: List[Optional[_T]], i: int, async_fn: Callable[[], Coroutine[Any, Any, _T]]
+) -> None:
+    results[i] = await async_fn()
+
+
+async def _wait_all(*async_fns: Callable[[], Coroutine[Any, Any, _T]]) -> List[_T]:
+    results: List[Optional[_T]] = [None] * len(async_fns)
+
+    async with anyio.create_task_group() as tg:
+        for i, async_fn in enumerate(async_fns):
+            tg.start_soon(_run_and_assign, results, i, async_fn)
+
+    return results  # type: ignore[return-value]
+
+
 def check_file_field(field: ModelField) -> None:
     field_info = field.field_info
     if isinstance(field_info, params.Form):
@@ -695,8 +716,7 @@ async def request_body_to_args(
                 and lenient_issubclass(field.type_, bytes)
                 and isinstance(value, sequence_types)
             ):
-                awaitables = [sub_value.read() for sub_value in value]
-                contents = await asyncio.gather(*awaitables)
+                contents = await _wait_all(*(sub_value.read for sub_value in value))
                 value = sequence_shape_to_type[field.shape](contents)
 
             v_, errors_ = field.validate(value, values, loc=loc)

pyproject.toml

@@ -32,7 +32,7 @@ classifiers = [
     "Topic :: Internet :: WWW/HTTP",
 ]
 requires = [
-    "starlette ==0.14.2",
+    "starlette ==0.15.0",
     "pydantic >=1.6.2,!=1.7,!=1.7.1,!=1.7.2,!=1.7.3,!=1.8,!=1.8.1,<2.0.0"
 ]
 description-file = "README.md"
@@ -43,9 +43,8 @@ Documentation = "https://fastapi.tiangolo.com/"
 
 [tool.flit.metadata.requires-extra]
 test = [
-    "pytest ==5.4.3",
-    "pytest-cov ==2.10.0",
-    "pytest-asyncio >=0.14.0,<0.15.0",
+    "pytest ==6.2.4",
+    "pytest-cov ==2.12.1",
     "mypy ==0.812",
     "flake8 >=3.8.3,<4.0.0",
     "black ==20.8b1",
@@ -62,7 +61,8 @@ test = [
     "async_generator >=1.10,<2.0.0",
     "python-multipart >=0.0.5,<0.0.6",
     "aiofiles >=0.5.0,<0.6.0",
-    "flask >=1.1.2,<2.0.0"
+    "flask >=1.1.2,<2.0.0",
+    "anyio[trio] >=3.1.0,<4",
 ]
 doc = [
     "mkdocs >=1.1.2,<2.0.0",
@@ -99,3 +99,18 @@ all = [
 [tool.isort]
 profile = "black"
 known_third_party = ["fastapi", "pydantic", "starlette"]
+
+[tool.pytest.ini_options]
+addopts = [
+  "--strict-config",
+  "--strict-markers",
+]
+xfail_strict = true
+junit_family = "xunit2"
+filterwarnings = [
+    "error",
+    'ignore:"@coroutine" decorator is deprecated since Python 3\.8, use "async def" instead:DeprecationWarning',
+    'ignore:The explicit passing of coroutine objects to asyncio\.wait\(\) is deprecated since Python 3\.8:DeprecationWarning',
+    'ignore:int_from_bytes is deprecated, use int\.from_bytes instead:cryptography.utils.CryptographyDeprecationWarning',
+    'ignore:Exception ignored in. <socket\.socket fd=-1:pytest.PytestUnraisableExceptionWarning',
+]

tests/test_tutorial/test_async_tests/test_main.py

@@ -3,6 +3,6 @@
 from docs_src.async_tests.test_main import test_root
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_testing():
     await test_root()

tests/test_tutorial/test_request_files/test_tutorial001.py

@@ -1,5 +1,3 @@
-import os
-
 from fastapi.testclient import TestClient
 
 from docs_src.request_files.tutorial001 import app
@@ -152,35 +150,35 @@ def test_post_body_json():
     assert response.json() == file_required
 
 
-def test_post_file(tmpdir):
-    path = os.path.join(tmpdir, "test.txt")
-    with open(path, "wb") as file:
-        file.write(b"<file content>")
+def test_post_file(tmp_path):
+    path = tmp_path / "test.txt"
+    path.write_bytes(b"<file content>")
 
     client = TestClient(app)
-    response = client.post("/files/", files={"file": open(path, "rb")})
+    with path.open("rb") as file:
+        response = client.post("/files/", files={"file": file})
     assert response.status_code == 200, response.text
     assert response.json() == {"file_size": 14}
 
 
-def test_post_large_file(tmpdir):
+def test_post_large_file(tmp_path):
     default_pydantic_max_size = 2 ** 16
-    path = os.path.join(tmpdir, "test.txt")
-    with open(path, "wb") as file:
-        file.write(b"x" * (default_pydantic_max_size + 1))
+    path = tmp_path / "test.txt"
+    path.write_bytes(b"x" * (default_pydantic_max_size + 1))
 
     client = TestClient(app)
-    response = client.post("/files/", files={"file": open(path, "rb")})
+    with path.open("rb") as file:
+        response = client.post("/files/", files={"file": file})
     assert response.status_code == 200, response.text
     assert response.json() == {"file_size": default_pydantic_max_size + 1}
 
 
-def test_post_upload_file(tmpdir):
-    path = os.path.join(tmpdir, "test.txt")
-    with open(path, "wb") as file:
-        file.write(b"<file content>")
+def test_post_upload_file(tmp_path):
+    path = tmp_path / "test.txt"
+    path.write_bytes(b"<file content>")
 
     client = TestClient(app)
-    response = client.post("/uploadfile/", files={"file": open(path, "rb")})
+    with path.open("rb") as file:
+        response = client.post("/uploadfile/", files={"file": file})
     assert response.status_code == 200, response.text
     assert response.json() == {"filename": "test.txt"}

tests/test_tutorial/test_request_files/test_tutorial002.py

@@ -1,5 +1,3 @@
-import os
-
 from fastapi.testclient import TestClient
 
 from docs_src.request_files.tutorial002 import app
@@ -172,42 +170,40 @@ def test_post_body_json():
     assert response.json() == file_required
 
 
-def test_post_files(tmpdir):
-    path = os.path.join(tmpdir, "test.txt")
-    with open(path, "wb") as file:
-        file.write(b"<file content>")
-    path2 = os.path.join(tmpdir, "test2.txt")
-    with open(path2, "wb") as file:
-        file.write(b"<file content2>")
+def test_post_files(tmp_path):
+    path = tmp_path / "test.txt"
+    path.write_bytes(b"<file content>")
+    path2 = tmp_path / "test2.txt"
+    path2.write_bytes(b"<file content2>")
 
     client = TestClient(app)
-    response = client.post(
-        "/files/",
-        files=(
-            ("files", ("test.txt", open(path, "rb"))),
-            ("files", ("test2.txt", open(path2, "rb"))),
-        ),
-    )
+    with path.open("rb") as file, path2.open("rb") as file2:
+        response = client.post(
+            "/files/",
+            files=(
+                ("files", ("test.txt", file)),
+                ("files", ("test2.txt", file2)),
+            ),
+        )
     assert response.status_code == 200, response.text
     assert response.json() == {"file_sizes": [14, 15]}
 
 
-def test_post_upload_file(tmpdir):
-    path = os.path.join(tmpdir, "test.txt")
-    with open(path, "wb") as file:
-        file.write(b"<file content>")
-    path2 = os.path.join(tmpdir, "test2.txt")
-    with open(path2, "wb") as file:
-        file.write(b"<file content2>")
+def test_post_upload_file(tmp_path):
+    path = tmp_path / "test.txt"
+    path.write_bytes(b"<file content>")
+    path2 = tmp_path / "test2.txt"
+    path2.write_bytes(b"<file content2>")
 
     client = TestClient(app)
-    response = client.post(
-        "/uploadfiles/",
-        files=(
-            ("files", ("test.txt", open(path, "rb"))),
-            ("files", ("test2.txt", open(path2, "rb"))),
-        ),
-    )
+    with path.open("rb") as file, path2.open("rb") as file2:
+        response = client.post(
+            "/uploadfiles/",
+            files=(
+                ("files", ("test.txt", file)),
+                ("files", ("test2.txt", file2)),
+            ),
+        )
     assert response.status_code == 200, response.text
     assert response.json() == {"filenames": ["test.txt", "test2.txt"]}
 

tests/test_tutorial/test_request_forms_and_files/test_tutorial001.py

@@ -1,6 +1,3 @@
-import os
-from pathlib import Path
-
 from fastapi.testclient import TestClient
 
 from docs_src.request_forms_and_files.tutorial001 import app
@@ -163,32 +160,30 @@ def test_post_body_json():
     assert response.json() == file_and_token_required
 
 
-def test_post_file_no_token(tmpdir):
-    path = os.path.join(tmpdir, "test.txt")
-    with open(path, "wb") as file:
-        file.write(b"<file content>")
+def test_post_file_no_token(tmp_path):
+    path = tmp_path / "test.txt"
+    path.write_bytes(b"<file content>")
 
     client = TestClient(app)
-    response = client.post("/files/", files={"file": open(path, "rb")})
+    with path.open("rb") as file:
+        response = client.post("/files/", files={"file": file})
     assert response.status_code == 422, response.text
     assert response.json() == token_required
 
 
-def test_post_files_and_token(tmpdir):
-    patha = Path(tmpdir) / "test.txt"
-    pathb = Path(tmpdir) / "testb.txt"
+def test_post_files_and_token(tmp_path):
+    patha = tmp_path / "test.txt"
+    pathb = tmp_path / "testb.txt"
     patha.write_text("<file content>")
     pathb.write_text("<file b content>")
 
     client = TestClient(app)
-    response = client.post(
-        "/files/",
-        data={"token": "foo"},
-        files={
-            "file": patha.open("rb"),
-            "fileb": ("testb.txt", pathb.open("rb"), "text/plain"),
-        },
-    )
+    with patha.open("rb") as filea, pathb.open("rb") as fileb:
+        response = client.post(
+            "/files/",
+            data={"token": "foo"},
+            files={"file": filea, "fileb": ("testb.txt", fileb, "text/plain")},
+        )
     assert response.status_code == 200, response.text
     assert response.json() == {
         "file_size": 14,

tests/test_tutorial/test_websockets/test_tutorial002.py

@@ -72,9 +72,11 @@ def test_websocket_with_header_and_query():
 
 def test_websocket_no_credentials():
     with pytest.raises(WebSocketDisconnect):
-        client.websocket_connect("/items/foo/ws")
+        with client.websocket_connect("/items/foo/ws"):
+            pass
 
 
 def test_websocket_invalid_data():
     with pytest.raises(WebSocketDisconnect):
-        client.websocket_connect("/items/foo/ws?q=bar&token=some-token")
+        with client.websocket_connect("/items/foo/ws?q=bar&token=some-token"):
+            pass