implement autofix for 91x

CONTRIBUTING.md

@@ -32,6 +32,9 @@ To check that all codes are tested and documented there's a test that error code
 ## Test generator
 Tests are automatically generated for files in the `tests/eval_files/` directory, with the code that it's testing interpreted from the file name. The file extension is split off, if there's a match for for `_py\d*` it strips that off and uses it to determine if there's a minimum python version for which the test should only run.
 
+### autofix files
+Checks that have autofixing can have a file in the `tests/autofix_files` directory matching the filename in `tests/eval_files`. The result of running the checker on the eval file with autofix enabled will then be compared to the content of the autofix file and will print a diff (if `-s` is on) and assert that the content is the same. `--generate-autofix` is added as a pytest flag to ease development, which will print a diff (with `-s`) and overwrite the content of the autofix file. Also see the magic line marker `pass # AUTOFIX_LINE ` below
+
 ### `error:`
 Lines containing `error:` are parsed as expecting an error of the code matching the file name, with everything on the line after the colon `eval`'d and passed as arguments to `flake8_trio.Error_codes[<error_code>].str_format`. The `globals` argument to `eval` contains a `lineno` variable assigned the current line number, and the `flake8_trio.Statement` namedtuple. The first element after `error:` *must* be an integer containing the column where the error on that line originates.
 #### `TRIOxxx:`
@@ -47,6 +50,9 @@ If a file is marked with `# NOTRIO` it will not replace instances of "trio" with
 #### `# ANYIO_NO_ERROR`
 A file which is marked with this will ignore all `# error` or `# TRIO...` comments when running with anyio. Use when an error is trio-specific and replacing "trio" with "anyio" should silence all errors.
 
+### `pass # AUTOFIX_LINE ...`
+Added to an eval file when the autofixed file is expected to insert a line `...` at that position. When autofix tests evaluate the diff the entire line is stripped from the autofixed file, and the leading `pass # AUTOFIX_LINE ` is stripped from the eval_file (leaving only `...`), so while the files will look slightly different when viewed with a difftool the autofix test should see `...` and `...`. Note that you may need to disable black/isort/other for the file.
+
 ## Running pytest outside tox
 If you don't want to bother with tox to quickly test stuff, you'll need to install the following dependencies:
 ```

flake8_trio/runner.py

@@ -9,11 +9,17 @@
 import ast
 import re
 from dataclasses import dataclass, field
+from itertools import chain
 from typing import TYPE_CHECKING
 
 import libcst as cst
 
-from .visitors import ERROR_CLASSES, ERROR_CLASSES_CST, utility_visitors
+from .visitors import (
+    ERROR_CLASSES,
+    ERROR_CLASSES_CST,
+    utility_visitors,
+    utility_visitors_cst,
+)
 
 if TYPE_CHECKING:
     from argparse import Namespace
@@ -104,6 +110,13 @@ def __init__(self, options: Namespace, module: Module):
         super().__init__()
         self.state = SharedState(options)
         self.options = options
+
+        # Could possibly enable/disable utility visitors here, if visitors declared
+        # dependencies
+        self.utility_visitors: tuple[Flake8TrioVisitor_cst, ...] = tuple(
+            v(self.state) for v in utility_visitors_cst
+        )
+
         self.visitors: tuple[Flake8TrioVisitor_cst, ...] = tuple(
             v(self.state) for v in ERROR_CLASSES_CST if self.selected(v.error_codes)
         )
@@ -112,7 +125,7 @@ def __init__(self, options: Namespace, module: Module):
     def run(self) -> Iterable[Error]:
         if not self.visitors:
             return
-        for v in self.visitors:
+        for v in chain(self.utility_visitors, self.visitors):
             self.module = cst.MetadataWrapper(self.module).visit(v)
         yield from self.state.problems
 

flake8_trio/visitors/__init__.py

@@ -12,11 +12,18 @@
 if TYPE_CHECKING:
     from .flake8triovisitor import Flake8TrioVisitor, Flake8TrioVisitor_cst
 
-__all__ = ["ERROR_CLASSES", "default_disabled_error_codes", "utility_visitors"]
+__all__ = [
+    "ERROR_CLASSES",
+    "ERROR_CLASSES_CST",
+    "default_disabled_error_codes",
+    "utility_visitors",
+    "utility_visitors_cst",
+]
 ERROR_CLASSES: set[type[Flake8TrioVisitor]] = set()
 ERROR_CLASSES_CST: set[type[Flake8TrioVisitor_cst]] = set()
-utility_visitors: set[type[Flake8TrioVisitor]] = set()
 default_disabled_error_codes: list[str] = []
+utility_visitors: set[type[Flake8TrioVisitor]] = set()
+utility_visitors_cst: set[type[Flake8TrioVisitor_cst]] = set()
 
 # Import all visitors so their decorators run, filling the above containers
 # This has to be done at the end to avoid circular imports

flake8_trio/visitors/flake8triovisitor.py

@@ -227,3 +227,13 @@ def error(
                 *args,
             )
         )
+
+    @property
+    def library(self) -> tuple[str, ...]:
+        return self.__state.library if self.__state.library else ("trio",)
+
+    # library_str not used in cst yet
+
+    def add_library(self, name: str) -> None:
+        if name not in self.__state.library:
+            self.__state.library = self.__state.library + (name,)

flake8_trio/visitors/helpers.py

@@ -19,6 +19,7 @@
     ERROR_CLASSES_CST,
     default_disabled_error_codes,
     utility_visitors,
+    utility_visitors_cst,
 )
 
 if TYPE_CHECKING:
@@ -58,6 +59,13 @@ def utility_visitor(c: type[T]) -> type[T]:
     return c
 
 
+def utility_visitor_cst(c: type[T_CST]) -> type[T_CST]:
+    assert not hasattr(c, "error_codes")
+    c.error_codes = {}
+    utility_visitors_cst.add(c)
+    return c
+
+
 def _get_identifier(node: ast.expr) -> str:
     if isinstance(node, ast.Name):
         return node.id