python-trio · Zac-HD · Jul 28, 2022 · Jul 28, 2022 · Jul 28, 2022 · Jul 28, 2022
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,6 +1,9 @@
 # Changelog
 *[CalVer, YY.month.patch](https://calver.org/)*
 
+## Future
+- Added TRIO105 check for not immediately `await`ing async trio functions.
+
 ## 22.7.3
 - Added TRIO102 check for unsafe checkpoints inside `finally:` blocks
 

diff --git a/README.md b/README.md
@@ -24,3 +24,4 @@ pip install flake8-trio
 - **TRIO101** `yield` inside a nursery or cancel scope is only safe when implementing a context manager - otherwise, it breaks exception handling.
 - **TRIO102** it's unsafe to await inside `finally:` unless you use a shielded
   cancel scope with a timeout"
+- **TRIO105** Calling a trio async function without immediately `await`ing it.
diff --git a/flake8_trio.py b/flake8_trio.py
@@ -255,6 +255,52 @@ def check_for_trio100(self, node: Union[ast.With, ast.AsyncWith]) -> None:
                 )
 
 
+trio_async_functions = (
+    "aclose_forcefully",
+    "open_file",
+    "open_ssl_over_tcp_listeners",
+    "open_ssl_over_tcp_stream",
+    "open_tcp_listeners",
+    "open_tcp_stream",
+    "open_unix_socket",
+    "run_process",
+    "serve_listeners",
+    "serve_ssl_over_tcp",
+    "serve_tcp",
+    "sleep",
+    "sleep_forever",
+    "sleep_until",
+)
+
+
+class Visitor105(ast.NodeVisitor):
+    def __init__(self) -> None:
+        super().__init__()
+        self.problems: List[Error] = []
+        self.node_stack: List[ast.AST] = []
+
+    def visit(self, node: ast.AST):
+        self.node_stack.append(node)
+        super().visit(node)
+        self.node_stack.pop()
+
+    def visit_Call(self, node: ast.Call):
+        if (
+            isinstance(node.func, ast.Attribute)
+            and isinstance(node.func.value, ast.Name)
+            and node.func.value.id == "trio"
+            and node.func.attr in trio_async_functions
+            and (
+                len(self.node_stack) < 2
+                or not isinstance(self.node_stack[-2], ast.Await)
+            )
+        ):
+            self.problems.append(
+                make_error(TRIO105, node.lineno, node.col_offset, node.func.attr)
+            )
+        self.generic_visit(node)
+
+
 class Plugin:
     name = __name__
     version = __version__
@@ -269,7 +315,7 @@ def from_filename(cls, filename: str) -> "Plugin":
         return cls(ast.parse(source))
 
     def run(self) -> Generator[Tuple[int, int, str, Type[Any]], None, None]:
-        for v in (Visitor, Visitor102):
+        for v in (Visitor, Visitor102, Visitor105):
             visitor = v()
             visitor.visit(self._tree)
             yield from visitor.problems
@@ -278,3 +324,4 @@ def run(self) -> Generator[Tuple[int, int, str, Type[Any]], None, None]:
 TRIO100 = "TRIO100: {} context contains no checkpoints, add `await trio.sleep(0)`"
 TRIO101 = "TRIO101: yield inside a nursery or cancel scope is only safe when implementing a context manager - otherwise, it breaks exception handling"
 TRIO102 = "TRIO102: it's unsafe to await inside `finally:` unless you use a shielded cancel scope with a timeout"
+TRIO105 = "TRIO105: Trio async function {} must be immediately awaited"
diff --git a/tests/test_flake8_trio.py b/tests/test_flake8_trio.py
@@ -1,15 +1,27 @@
 import ast
+import inspect
 import os
 import site
 import sys
 import unittest
 from pathlib import Path
 
 import pytest
+import trio  # type: ignore
 from hypothesis import HealthCheck, given, settings
 from hypothesmith import from_grammar, from_node
 
-from flake8_trio import TRIO100, TRIO101, TRIO102, Error, Plugin, Visitor, make_error
+from flake8_trio import (
+    TRIO100,
+    TRIO101,
+    TRIO102,
+    TRIO105,
+    Error,
+    Plugin,
+    Visitor,
+    make_error,
+    trio_async_functions,
+)
 
 
 class Flake8TrioTestCase(unittest.TestCase):
@@ -71,6 +83,36 @@ def test_trio102(self):
             make_error(TRIO102, 123, 12),
         )
 
+    def test_trio105(self):
+        self.assert_expected_errors(
+            "trio105.py",
+            make_error(TRIO105, 25, 4, "aclose_forcefully"),
+            make_error(TRIO105, 26, 4, "open_file"),
+            make_error(TRIO105, 27, 4, "open_ssl_over_tcp_listeners"),
+            make_error(TRIO105, 28, 4, "open_ssl_over_tcp_stream"),
+            make_error(TRIO105, 29, 4, "open_tcp_listeners"),
+            make_error(TRIO105, 30, 4, "open_tcp_stream"),
+            make_error(TRIO105, 31, 4, "open_unix_socket"),
+            make_error(TRIO105, 32, 4, "run_process"),
+            make_error(TRIO105, 33, 4, "serve_listeners"),
+            make_error(TRIO105, 34, 4, "serve_ssl_over_tcp"),
+            make_error(TRIO105, 35, 4, "serve_tcp"),
+            make_error(TRIO105, 36, 4, "sleep"),
+            make_error(TRIO105, 37, 4, "sleep_forever"),
+            make_error(TRIO105, 38, 4, "sleep_until"),
+            make_error(TRIO105, 45, 15, "open_file"),
+            make_error(TRIO105, 50, 8, "open_file"),
+        )
+
+        self.assertEqual(
+            set(trio_async_functions),
+            {
+                o[0]
+                for o in inspect.getmembers(trio)  # type: ignore
+                if inspect.iscoroutinefunction(o[1])
+            },
+        )
+
 
 @pytest.mark.fuzz
 class TestFuzz(unittest.TestCase):

diff --git a/tests/trio105.py b/tests/trio105.py
@@ -0,0 +1,51 @@
+import trio
+
+
+async def foo():
+    # not async
+    trio.run()
+
+    # safely awaited
+    await trio.aclose_forcefully()
+    await trio.open_file()
+    await trio.open_ssl_over_tcp_listeners()
+    await trio.open_ssl_over_tcp_stream()
+    await trio.open_tcp_listeners()
+    await trio.open_tcp_stream()
+    await trio.open_unix_socket()
+    await trio.run_process()
+    await trio.serve_listeners()
+    await trio.serve_ssl_over_tcp()
+    await trio.serve_tcp()
+    await trio.sleep()
+    await trio.sleep_forever()
+    await trio.sleep_until()
+
+    # errors
+    trio.aclose_forcefully()
+    trio.open_file()
+    trio.open_ssl_over_tcp_listeners()
+    trio.open_ssl_over_tcp_stream()
+    trio.open_tcp_listeners()
+    trio.open_tcp_stream()
+    trio.open_unix_socket()
+    trio.run_process()
+    trio.serve_listeners()
+    trio.serve_ssl_over_tcp()
+    trio.serve_tcp()
+    trio.sleep()
+    trio.sleep_forever()
+    trio.sleep_until()
+
+    # safe
+    async with await trio.open_file() as f:
+        pass
+
+    # error
+    async with trio.open_file() as f:
+        pass
+
+    # safe in theory, but deemed sufficiently poor style that parsing
+    # it isn't supported
    k = trio.open_file()
+    await k
diff --git a/tox.ini b/tox.ini
@@ -35,6 +35,7 @@ deps =
     #pytest-xdist
     hypothesis
     hypothesmith
+    trio
 commands =
     pytest #{posargs:-n auto}