8000 Added #6: Async functions must have checkpoints on every code path · jakkdl/flake8-async@221ee28 · GitHub
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Added python-trio#6: Async functions must have checkpoints on every code path
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‎CHANGELOG.md

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Original file line numberDiff line numberDiff line change
@@ -2,6 +2,7 @@
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*[CalVer, YY.month.patch](https://calver.org/)*
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## Future
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- Added TRIOXXX check: Async functions must have at least one checkpoint on every code path, unless an exception is raised
56
- Add TRIO103: `except BaseException` or `except trio.Cancelled` with a code path that doesn't re-raise
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- Add TRIO104: "Cancelled and BaseException must be re-raised" if user tries to return or raise a different exception.
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‎README.md

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@@ -28,3 +28,4 @@ pip install flake8-trio
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- **TRIO104**: `Cancelled` and `BaseException` must be re-raised - when a user tries to `return` or `raise` a different exception.
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- **TRIO105**: Calling a trio async function without immediately `await`ing it.
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- **TRIO106**: trio must be imported with `import trio` for the linter to work
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- **TRIO300**: Async functions must have at least one checkpoint on every code path, unless an exception is raised

‎flake8_trio.py

Lines changed: 74 additions & 1 deletion
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@@ -11,7 +11,17 @@
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import ast
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import tokenize
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from typing import Any, Collection, Generator, List, Optional, Tuple, Type, Union
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from typing import (
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Any,
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Collection,
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Generator,
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Iterable,
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List,
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Optional,
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Tuple,
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Type,
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Union,
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)
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# CalVer: YY.month.patch, e.g. first release of July 2022 == "22.7.1"
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__version__ = "22.7.4"
@@ -47,6 +57,13 @@ def run(cls, tree: ast.AST) -> Generator[Error, None, None]:
4757
visitor.visit(tree)
4858
yield from visitor.problems
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60+
def visit_nodes(self, nodes: Iterable[ast.AST]) -> None:
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for node in nodes:
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self.visit(node)
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64+
def error(self, error: str, lineno: int, col: int, *args: Any, **kwargs: Any):
65+
self.problems.append(make_error(error, lineno, col, *args, **kwargs))
66+
5067

5168
class TrioScope:
5269
def __init__(self, node: ast.Call, funcname: str, packagename: str):
@@ -462,6 +479,61 @@ def visit_Call(self, node: ast.Call):
462479
self.generic_visit(node)
463480

464481

482+
class Visitor300(Flake8TrioVisitor):
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def __init__(self) -> None:
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super().__init__()
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self.all_await = False
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487+
def visit_AsyncFunctionDef(self, node: ast.AsyncFunctionDef):
488+
outer = self.all_await
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490+
self.all_await = False
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self.generic_visit(node)
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if not self.all_await:
494+
self.error(TRIO300, node.lineno, node.col_offset)
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496+
self.all_await = outer
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498+
def visit_Await(
499+
self, node: Union[ast.Await, ast.AsyncFor, ast.AsyncWith, ast.Raise]
500+
):
501+
self.generic_visit(node)
502+
self.all_await = True
503+
504+
visit_AsyncFor = visit_Await
505+
visit_AsyncWith = visit_Await
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visit_Raise = visit_Await
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508+
def visit_Try(self, node: ast.Try):
509+
self.visit_nodes(node.body)
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511+
# disregard await's in excepts
512+
outer = self.all_await
513+
self.visit_nodes(node.handlers)
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self.all_await = outer
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516+
self.visit_nodes(node.finalbody)
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518+
def visit_If(self, node: ast.If):
519+
if self.all_await:
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self.generic_visit(node)
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return
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self.visit_nodes(node.body)
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body_await = self.all_await
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self.all_await = False
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self.visit_nodes(node.orelse)
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self.all_await = body_await and self.all_await
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def visit_While(self, node: Union[ast.While, ast.For]):
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outer = self.all_await
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self.generic_visit(node)
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self.all_await = outer
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visit_For = visit_While
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465537
class Plugin:
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name = __name__
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version = __version__
@@ -487,3 +559,4 @@ def run(self) -> Generator[Tuple[int, int, str, Type[Any]], None, None]:
487559
TRIO104 = "TRIO104: Cancelled (and therefore BaseException) must be re-raised"
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TRIO105 = "TRIO105: Trio async function {} must be immediately awaited"
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TRIO106 = "TRIO106: trio must be imported with `import trio` for the linter to work"
562+
TRIO300 = "TRIO300: Async functions must have at least one checkpoint on every code path, unless an exception is raised"

‎tests/test_flake8_trio.py

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Original file line numberDiff line numberDiff line change
@@ -20,6 +20,7 @@
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TRIO104,
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TRIO105,
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TRIO106,
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TRIO300,
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Error,
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Plugin,
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make_error,
@@ -94,7 +95,7 @@ def test_trio102(self):
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make_error(TRIO102, 92, 8),
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make_error(TRIO102, 94, 8),
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make_error(TRIO102, 101, 12),
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make_error(TRIO102, 123, 12),
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make_error(TRIO102, 124, 12),
9899
)
99100

100101
def test_trio103_104(self):
@@ -173,6 +174,20 @@ def test_trio106(self):
173174
make_error(TRIO106, 6, 0),
174175
)
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177+
def test_trio300(self):
178+
self.assert_expected_errors(
179+
"trio300.py",
180+
make_error(TRIO300, 10, 0),
181+
make_error(TRIO300, 15, 0),
182+
make_error(TRIO300, 28, 0),
183+
make_error(TRIO300, 33, 0),
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make_error(TRIO300, 46, 0),
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make_error(TRIO300, 51, 0),
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make_error(TRIO300, 59, 0),
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make_error(TRIO300, 90, 0),
188+
make_error(TRIO300, 99, 0),
189+
)
190+
176191

177192
@pytest.mark.fuzz
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class TestFuzz(unittest.TestCase):

‎tests/trio100_py39.py

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@@ -14,3 +14,4 @@ async def function_name():
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trio.move_on_after(5), # error
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):
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pass
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await function_name() # avoid TRIO300

‎tests/trio102.py

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@@ -5,7 +5,7 @@
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async def foo():
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try:
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pass
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await foo() # avoid TRIO300
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finally:
1010
with trio.move_on_after(deadline=30) as s:
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s.shield = True
@@ -107,11 +107,12 @@ async def foo2():
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yield 1
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finally:
109109
await foo() # safe
110+
await foo() # avoid TRIO300
110111

111112

112113
async def foo3():
113114
try:
114-
pass
115+
await foo() # avoid TRIO300
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finally:
116117
with trio.move_on_after(30) as s, trio.fail_after(5):
117118
s.shield = True

‎tests/trio300.py

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@@ -0,0 +1,114 @@
1+
import trio
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3+
_ = ""
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5+
6+
async def foo():
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await foo()
8+
9+
10+
async def foo2(): # error
11+
...
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13+
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# If
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async def foo_if_1(): # error
16+
if _:
17+
await foo()
18+
19+
20+
async def foo_if_2():
21+
if _:
22+
await foo()
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else:
24+
await foo()
25+
26+
27+
# loops
28+
async def foo_while_1(): # error
29+
while _:
30+
await foo()
31+
32+
33+
async def foo_while_2(): # error: due to not wanting to handle continue/break semantics
34+
while _:
35+
await foo()
36+
else:
37+
await foo()
38+
39+
40+
async def foo_while_3(): # safe
41+
await foo()
42+
while _:
43+
...
44+
45+
46+
async def foo_for_1(): # error
47+
for __ in _:
48+
await foo()
49+
50+
51+
async def foo_for_2(): # error: due to not wanting to handle continue/break semantics
52+
for __ in _:
53+
await foo()
54+
else:
55+
await foo()
56+
57+
58+
# try
59+
async def foo_try_1(): # error
60+
try:
61+
...
62+
except ValueError:
63+
await foo()
64+
except:
65+
await foo()
66+
67+
68+
async def foo_try_2(): # safe
69+
try:
70+
await foo()
71+
except ValueError:
72+
await foo()
73+
except:
74+
await foo()
75+
76+
77+
async def foo_try_3(): # safe
78+
try:
79+
await foo()
80+
except ValueError:
81+
await foo()
82+
except:
83+
await foo()
84+
finally:
85+
with trio.CancelScope(deadline=30, shield=True): # avoid TRIO102
86+
await foo()
87+
88+
89+
# early return
90+
async def foo_return_1(): # error
91+
return
92+
93+
94+
async def foo_return_2(): # safe
95+
await foo()
96+
return
97+
98+
99+
async def foo_return_3(): # error
100+
if _:
101+
await foo()
102+
return
103+
104+
105+
# raise
106+
async def foo_raise_1(): # safe
107+
raise ValueError()
108+
109+
110+
async def foo_raise_2(): # safe
111+
if _:
112+
await foo()
113+
else:
114+
raise ValueError()

‎tox.ini

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@@ -28,7 +28,7 @@ ignore_errors =
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commands =
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shed
3030
flake8 --exclude .*,tests/trio*.py
31-
pyright --pythonversion 3.10
31+
pyright --pythonversion 3.10 --warnings
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3333
# generate py38-test py39-test and test
3434
[testenv:{py38-, py39-,}test]

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