Implement flake8-async plugin (#4432)

LICENSE

@@ -814,6 +814,31 @@ are:
     SOFTWARE.
   """
 
+- flake8-async, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2022 Cooper Lees
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
 - flake8-type-checking, licensed as follows:
   """
     Copyright (c) 2021, Sondre Lillebø Gundersen

README.md

@@ -249,6 +249,7 @@ quality tools, including:
 - [eradicate](https://pypi.org/project/eradicate/)
 - [flake8-2020](https://pypi.org/project/flake8-2020/)
 - [flake8-annotations](https://pypi.org/project/flake8-annotations/)
+- [flake8-async](https://pypi.org/project/flake8-async)
 - [flake8-bandit](https://pypi.org/project/flake8-bandit/) ([#1646](https://github.com/charliermarsh/ruff/issues/1646))
 - [flake8-blind-except](https://pypi.org/project/flake8-blind-except/)
 - [flake8-boolean-trap](https://pypi.org/project/flake8-boolean-trap/)

crates/ruff/resources/test/fixtures/flake8_async/ASYNC100.py

@@ -0,0 +1,23 @@
+import urllib.request
+import requests
+import httpx
+
+
+async def foo():
+    urllib.request.urlopen("http://example.com/foo/bar").read()
+
+
+async def foo():
+    requests.get()
+
+
+async def foo():
+    httpx.get()
+
+
+async def foo():
+    requests.post()
+
+
+async def foo():
+    httpx.post()

crates/ruff/resources/test/fixtures/flake8_async/ASYNC101.py

@@ -0,0 +1,31 @@
+import os
+import subprocess
+import time
+
+
+async def foo():
+    open("foo")
+
+
+async def foo():
+    time.sleep(1)
+
+
+async def foo():
+    subprocess.run("foo")
+
+
+async def foo():
+    subprocess.call("foo")
+
+
+async def foo():
+    subprocess.foo(0)
+
+
+async def foo():
+    os.wait4(10)
+
+
+async def foo():
+    os.wait(12)

crates/ruff/resources/test/fixtures/flake8_async/ASYNC102.py

@@ -0,0 +1,13 @@
+import os
+
+
+async def foo():
+    os.popen()
+
+
+async def foo():
+    os.spawnl()
+
+
+async def foo():
+    os.fspath("foo")

crates/ruff/src/checkers/ast/mod.rs

@@ -42,9 +42,9 @@ use crate::importer::Importer;
 use crate::noqa::NoqaMapping;
 use crate::registry::{AsRule, Rule};
 use crate::rules::{
-    flake8_2020, flake8_annotations, flake8_bandit, flake8_blind_except, flake8_boolean_trap,
+    flake8_2020, flake8_annotations, flake8_async, flake8_bandit, flake8_blind_except,
-    flake8_bugbear, flake8_builtins, flake8_comprehensions, flake8_datetimez, flake8_debugger,
+    flake8_boolean_trap, flake8_bugbear, flake8_builtins, flake8_comprehensions, flake8_datetimez,
-    flake8_django, flake8_errmsg, flake8_future_annotations, flake8_gettext,
+    flake8_debugger, flake8_django, flake8_errmsg, flake8_future_annotations, flake8_gettext,
     flake8_implicit_str_concat, flake8_import_conventions, flake8_logging_format, flake8_pie,
     flake8_print, flake8_pyi, flake8_pytest_style, flake8_raise, flake8_return, flake8_self,
     flake8_simplify, flake8_tidy_imports, flake8_type_checking, flake8_unused_arguments,
@@ -2584,6 +2584,29 @@ where
                     pyupgrade::rules::use_pep604_isinstance(self, expr, func, args);
                 }
 
+                // flake8-async
+                if self
+                    .settings
+                    .rules
+                    .enabled(Rule::BlockingHttpCallInAsyncFunction)
+                {
+                    flake8_async::rules::blocking_http_call(self, expr);
+                }
+                if self
+                    .settings
+                    .rules
+                    .enabled(Rule::OpenSleepOrSubprocessInAsyncFunction)
+                {
+                    flake8_async::rules::open_sleep_or_subprocess_call(self, expr);
+                }
+                if self
+                    .settings
+                    .rules
+                    .enabled(Rule::BlockingOsCallInAsyncFunction)
+                {
+                    flake8_async::rules::blocking_os_call(self, expr);
+                }
+
                 // flake8-print
                 if self
                     .settings

crates/ruff/src/codes.rs

@@ -215,6 +215,11 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<Rule> {
         (Pylint, "W3301") => Rule::NestedMinMax,
         (Pylint, "E0241") => Rule::DuplicateBases,
 
+        // flake8-async
+        (Flake8Async, "100") => Rule::BlockingHttpCallInAsyncFunction,
+        (Flake8Async, "101") => Rule::OpenSleepOrSubprocessInAsyncFunction,
+        (Flake8Async, "102") => Rule::BlockingOsCallInAsyncFunction,
+
         // flake8-builtins
         (Flake8Builtins, "001") => Rule::BuiltinVariableShadowing,
         (Flake8Builtins, "002") => Rule::BuiltinArgumentShadowing,

crates/ruff/src/registry.rs

@@ -191,6 +191,10 @@ ruff_macros::register_rules!(
     rules::pylint::rules::UnexpectedSpecialMethodSignature,
     rules::pylint::rules::NestedMinMax,
     rules::pylint::rules::DuplicateBases,
+    // flake8-async
+    rules::flake8_async::rules::BlockingHttpCallInAsyncFunction,
+    rules::flake8_async::rules::OpenSleepOrSubprocessInAsyncFunction,
+    rules::flake8_async::rules::BlockingOsCallInAsyncFunction,
     // flake8-builtins
     rules::flake8_builtins::rules::BuiltinVariableShadowing,
     rules::flake8_builtins::rules::BuiltinArgumentShadowing,
@@ -735,6 +739,9 @@ pub enum Linter {
     /// [flake8-annotations](https://pypi.org/project/flake8-annotations/)
     #[prefix = "ANN"]
     Flake8Annotations,
+    /// [flake8-async](https://pypi.org/project/flake8-async/)
+    #[prefix = "ASYNC"]
+    Flake8Async,
     /// [flake8-bandit](https://pypi.org/project/flake8-bandit/)
     #[prefix = "S"]
     Flake8Bandit,

crates/ruff/src/rules/flake8_async/mod.rs

@@ -0,0 +1,28 @@
+//! Rules from [flake8-async](https://pypi.org/project/flake8-async/).
+pub(crate) mod rules;
+
+#[cfg(test)]
+mod tests {
+    use std::path::Path;
+
+    use anyhow::Result;
+    use test_case::test_case;
+
+    use crate::assert_messages;
+    use crate::registry::Rule;
+    use crate::settings::Settings;
+    use crate::test::test_path;
+
+    #[test_case(Rule::BlockingHttpCallInAsyncFunction, Path::new("ASYNC100.py"); "ASYNC100")]
+    #[test_case(Rule::OpenSleepOrSubprocessInAsyncFunction, Path::new("ASYNC101.py"); "ASYNC101")]
+    #[test_case(Rule::BlockingOsCallInAsyncFunction, Path::new("ASYNC102.py"); "ASYNC102")]
+    fn rules(rule_code: Rule, path: &Path) -> Result<()> {
+        let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());
+        let diagnostics = test_path(
+            Path::new("flake8_async").join(path).as_path(),
+            &Settings::for_rule(rule_code),
+        )?;
+        assert_messages!(snapshot, diagnostics);
+        Ok(())
+    }
+}

crates/ruff/src/rules/flake8_async/rules.rs

@@ -0,0 +1,224 @@
+use rustpython_parser::ast;
+use rustpython_parser::ast::{Expr, ExprKind};
+
+use ruff_diagnostics::{Diagnostic, Violation};
+use ruff_macros::{derive_message_formats, violation};
+use ruff_python_semantic::context::Context;
+use ruff_python_semantic::scope::{FunctionDef, ScopeKind};
+
+use crate::checkers::ast::Checker;
+
+/// ## What it does
+/// Checks that async functions do not contain blocking HTTP calls.
+///
+/// ## Why is this bad?
+/// Blocking an async function via a blocking HTTP call will block the entire
+/// event loop, preventing it from executing other tasks while waiting for the
+/// HTTP response, negating the benefits of asynchronous programming.
+///
+/// Instead of making a blocking HTTP call, use an asynchronous HTTP client
+/// library such as `aiohttp` or `httpx`.
+///
+/// ## Example
+/// ```python
+/// async def fetch():
+///     urllib.request.urlopen("https://example.com/foo/bar").read()
+/// ```
+///
+/// Use instead:
+/// ```python
+/// async def fetch():
+///     async with aiohttp.ClientSession() as session:
+///         async with session.get("https://example.com/foo/bar") as resp:
+///             ...
+/// ```
+#[violation]
+pub struct BlockingHttpCallInAsyncFunction;
+
+impl Violation for BlockingHttpCallInAsyncFunction {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Async functions should not call blocking HTTP methods")
+    }
+}
+
+const BLOCKING_HTTP_CALLS: &[&[&str]] = &[
+    &["urllib", "request", "urlopen"],
+    &["httpx", "get"],
+    &["httpx", "post"],
+    &["httpx", "delete"],
+    &["httpx", "patch"],
+    &["httpx", "put"],
+    &["httpx", "head"],
+    &["httpx", "connect"],
+    &["httpx", "options"],
+    &["httpx", "trace"],
+    &["requests", "get"],
+    &["requests", "post"],
+    &["requests", "delete"],
+    &["requests", "patch"],
+    &["requests", "put"],
+    &["requests", "head"],
+    &["requests", "connect"],
+    &["requests", "options"],
+    &["requests", "trace"],
+];
+
+/// ASYNC100
+pub(crate) fn blocking_http_call(checker: &mut Checker, expr: &Expr) {
+    if in_async_function(&checker.ctx) {
+        if let ExprKind::Call(ast::ExprCall { func, .. }) = &expr.node {
+            if let Some(call_path) = checker.ctx.resolve_call_path(func) {
+                if BLOCKING_HTTP_CALLS.contains(&call_path.as_slice()) {
+                    checker
+                        .diagnostics
+                        .push(Diagnostic::new(BlockingHttpCallInAsyncFunction, func.range));
+                }
+            }
+        }
+    }
+}
+
+/// ## What it does
+/// Checks that async functions do not contain calls to `open`, `time.sleep`,
+/// or `subprocess` methods.
+///
+/// ## Why is this bad?
+/// Blocking an async function via a blocking call will block the entire
+/// event loop, preventing it from executing other tasks while waiting for the
+/// call to complete, negating the benefits of asynchronous programming.
+///
+/// Instead of making a blocking call, use an equivalent asynchronous library
+/// or function.
+///
+/// ## Example
+/// ```python
+/// async def foo():
+///     time.sleep(1000)
+/// ```
+///
+/// Use instead:
+/// ```python
+/// async def foo():
+///     await asyncio.sleep(1000)
+/// ```
+#[violation]
+pub struct OpenSleepOrSubprocessInAsyncFunction;
+
+impl Violation for OpenSleepOrSubprocessInAsyncFunction {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Async functions should not call `open`, `time.sleep`, or `subprocess` methods")
+    }
+}
+
+const OPEN_SLEEP_OR_SUBPROCESS_CALL: &[&[&str]] = &[
+    &["", "open"],
+    &["time", "sleep"],
+    &["subprocess", "run"],
+    &["subprocess", "Popen"],
+    // Deprecated subprocess calls:
+    &["subprocess", "call"],
+    &["subprocess", "check_call"],
+    &["subprocess", "check_output"],
+    &["subprocess", "getoutput"],
+    &["subprocess", "getstatusoutput"],
+    &["os", "wait"],
+    &["os", "wait3"],
+    &["os", "wait4"],
+    &["os", "waitid"],
+    &["os", "waitpid"],
+];
+
+/// ASYNC101
+pub(crate) fn open_sleep_or_subprocess_call(checker: &mut Checker, expr: &Expr) {
+    if in_async_function(&checker.ctx) {
+        if let ExprKind::Call(ast::ExprCall { func, .. }) = &expr.node {
+            if let Some(call_path) = checker.ctx.resolve_call_path(func) {
+                if OPEN_SLEEP_OR_SUBPROCESS_CALL.contains(&call_path.as_slice()) {
+                    checker.diagnostics.push(Diagnostic::new(
+                        OpenSleepOrSubprocessInAsyncFunction,
+                        func.range,
+                    ));
+                }
+            }
+        }
+    }
+}
+
+/// ## What it does
+/// Checks that async functions do not contain calls to blocking synchronous
+/// process calls via the `os` module.
+///
+/// ## Why is this bad?
+/// Blocking an async function via a blocking call will block the entire
+/// event loop, preventing it from executing other tasks while waiting for the
+/// call to complete, negating the benefits of asynchronous programming.
+///
+/// Instead of making a blocking call, use an equivalent asynchronous library
+/// or function.
+///
+/// ## Example
+/// ```python
+/// async def foo():
+///     os.popen()
+/// ```
+///
+/// Use instead:
+/// ```python
+/// def foo():
+///     os.popen()
+/// ```
+#[violation]
+pub struct BlockingOsCallInAsyncFunction;
+
+impl Violation for BlockingOsCallInAsyncFunction {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Async functions should not call synchronous `os` methods")
+    }
+}
+
+const UNSAFE_OS_METHODS: &[&[&str]] = &[
+    &["os", "popen"],
+    &["os", "posix_spawn"],
+    &["os", "posix_spawnp"],
+    &["os", "spawnl"],
+    &["os", "spawnle"],
+    &["os", "spawnlp"],
+    &["os", "spawnlpe"],
+    &["os", "spawnv"],
+    &["os", "spawnve"],
+    &["os", "spawnvp"],
+    &["os", "spawnvpe"],
+    &["os", "system"],
+];
+
+/// ASYNC102
+pub(crate) fn blocking_os_call(checker: &mut Checker, expr: &Expr) {
+    if in_async_function(&checker.ctx) {
+        if let ExprKind::Call(ast::ExprCall { func, .. }) = &expr.node {
+            if let Some(call_path) = checker.ctx.resolve_call_path(func) {
+                if UNSAFE_OS_METHODS.contains(&call_path.as_slice()) {
+                    checker
+                        .diagnostics
+                        .push(Diagnostic::new(BlockingOsCallInAsyncFunction, func.range));
+                }
+            }
+        }
+    }
+}
+
+/// Return `true` if the [`Context`] is inside an async function definition.
+fn in_async_function(context: &Context) -> bool {
+    context
+        .scopes()
+        .find_map(|scope| {
+            if let ScopeKind::Function(FunctionDef { async_, .. }) = &scope.kind {
+                Some(*async_)
+            } else {
+                None
+            }
+        })
+        .unwrap_or(false)
+}

crates/ruff/src/rules/flake8_async/snapshots/ruff__rules__flake8_async__tests__ASYNC100_ASYNC100.py.snap

@@ -0,0 +1,39 @@
+---
+source: crates/ruff/src/rules/flake8_async/mod.rs
+---
+ASYNC100.py:7:5: ASYNC100 Async functions should not call blocking HTTP methods
+  |
+7 | async def foo():
+8 |     urllib.request.urlopen("http://example.com/foo/bar").read()
+  |     ^^^^^^^^^^^^^^^^^^^^^^ ASYNC100
+  |
+
+ASYNC100.py:11:5: ASYNC100 Async functions should not call blocking HTTP methods
+   |
+11 | async def foo():
+12 |     requests.get()
+   |     ^^^^^^^^^^^^ ASYNC100
+   |
+
+ASYNC100.py:15:5: ASYNC100 Async functions should not call blocking HTTP methods
+   |
+15 | async def foo():
+16 |     httpx.get()
+   |     ^^^^^^^^^ ASYNC100
+   |
+
+ASYNC100.py:19:5: ASYNC100 Async functions should not call blocking HTTP methods
+   |
+19 | async def foo():
+20 |     requests.post()
+   |     ^^^^^^^^^^^^^ ASYNC100
+   |
+
+ASYNC100.py:23:5: ASYNC100 Async functions should not call blocking HTTP methods
+   |
+23 | async def foo():
+24 |     httpx.post()
+   |     ^^^^^^^^^^ ASYNC100
+   |
+
+

crates/ruff/src/rules/flake8_async/snapshots/ruff__rules__flake8_async__tests__ASYNC101_ASYNC101.py.snap

@@ -0,0 +1,46 @@
+---
+source: crates/ruff/src/rules/flake8_async/mod.rs
+---
+ASYNC101.py:7:5: ASYNC101 Async functions should not call `open`, `time.sleep`, or `subprocess` methods
+  |
+7 | async def foo():
+8 |     open("foo")
+  |     ^^^^ ASYNC101
+  |
+
+ASYNC101.py:11:5: ASYNC101 Async functions should not call `open`, `time.sleep`, or `subprocess` methods
+   |
+11 | async def foo():
+12 |     time.sleep(1)
+   |     ^^^^^^^^^^ ASYNC101
+   |
+
+ASYNC101.py:15:5: ASYNC101 Async functions should not call `open`, `time.sleep`, or `subprocess` methods
+   |
+15 | async def foo():
+16 |     subprocess.run("foo")
+   |     ^^^^^^^^^^^^^^ ASYNC101
+   |
+
+ASYNC101.py:19:5: ASYNC101 Async functions should not call `open`, `time.sleep`, or `subprocess` methods
+   |
+19 | async def foo():
+20 |     subprocess.call("foo")
+   |     ^^^^^^^^^^^^^^^ ASYNC101
+   |
+
+ASYNC101.py:27:5: ASYNC101 Async functions should not call `open`, `time.sleep`, or `subprocess` methods
+   |
+27 | async def foo():
+28 |     os.wait4(10)
+   |     ^^^^^^^^ ASYNC101
+   |
+
+ASYNC101.py:31:5: ASYNC101 Async functions should not call `open`, `time.sleep`, or `subprocess` methods
+   |
+31 | async def foo():
+32 |     os.wait(12)
+   |     ^^^^^^^ ASYNC101
+   |
+
+

crates/ruff/src/rules/flake8_async/snapshots/ruff__rules__flake8_async__tests__ASYNC102_ASYNC102.py.snap

@@ -0,0 +1,18 @@
+---
+source: crates/ruff/src/rules/flake8_async/mod.rs
+---
+ASYNC102.py:5:5: ASYNC102 Async functions should not call synchronous `os` methods
+  |
+5 | async def foo():
+6 |     os.popen()
+  |     ^^^^^^^^ ASYNC102
+  |
+
+ASYNC102.py:9:5: ASYNC102 Async functions should not call synchronous `os` methods
+   |
+ 9 | async def foo():
+10 |     os.spawnl()
+   |     ^^^^^^^^^ ASYNC102
+   |
+
+

crates/ruff/src/rules/mod.rs

@@ -2,6 +2,7 @@
 pub mod eradicate;
 pub mod flake8_2020;
 pub mod flake8_annotations;
+pub mod flake8_async;
 pub mod flake8_bandit;
 pub mod flake8_blind_except;
 pub mod flake8_boolean_trap;

docs/faq.md

@@ -33,6 +33,7 @@ natively, including:
 - [eradicate](https://pypi.org/project/eradicate/)
 - [flake8-2020](https://pypi.org/project/flake8-2020/)
 - [flake8-annotations](https://pypi.org/project/flake8-annotations/)
+- [flake8-async](https://pypi.org/project/flake8-async)
 - [flake8-bandit](https://pypi.org/project/flake8-bandit/) ([#1646](https://github.com/charliermarsh/ruff/issues/1646))
 - [flake8-blind-except](https://pypi.org/project/flake8-blind-except/)
 - [flake8-boolean-trap](https://pypi.org/project/flake8-boolean-trap/)
@@ -133,6 +134,7 @@ Today, Ruff can be used to replace Flake8 when used with any of the following pl
 
 - [flake8-2020](https://pypi.org/project/flake8-2020/)
 - [flake8-annotations](https://pypi.org/project/flake8-annotations/)
+- [flake8-async](https://pypi.org/project/flake8-async)
 - [flake8-bandit](https://pypi.org/project/flake8-bandit/) ([#1646](https://github.com/charliermarsh/ruff/issues/1646))
 - [flake8-blind-except](https://pypi.org/project/flake8-blind-except/)
 - [flake8-boolean-trap](https://pypi.org/project/flake8-boolean-trap/)

ruff.schema.json

@@ -1521,6 +1521,12 @@
         "ARG003",
         "ARG004",
         "ARG005",
+        "ASYNC",
+        "ASYNC1",
+        "ASYNC10",
+        "ASYNC100",
+        "ASYNC101",
+        "ASYNC102",
         "B",
         "B0",
         "B00",