add more flake8 lints (#2653)

.pre-commit-config.yaml

@@ -35,7 +35,10 @@ repos:
     rev: 3.9.2
     hooks:
       - id: flake8
-        additional_dependencies: [flake8-bugbear]
+        additional_dependencies:
+          - flake8-bugbear
+          - flake8-comprehensions
+          - flake8-simplify
 
   - repo: https://github.com/pre-commit/mirrors-mypy
     rev: v0.910

CHANGES.md

@@ -7,6 +7,7 @@
 - Fixed Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
 - Fixed `match` statements with open sequence subjects, like `match a, b:` (#2639)
 - Fixed assignment to environment variables in Jupyter Notebooks (#2642)
+- Add `flake8-simplify` and `flake8-comprehensions` plugins (#2653)
 
 ## 21.11b1
 

src/black/__init__.py

@@ -181,7 +181,7 @@ def validate_regex(
 
 
 @click.command(
-    context_settings=dict(help_option_names=["-h", "--help"]),
+    context_settings={"help_option_names": ["-h", "--help"]},
     # While Click does set this field automatically using the docstring, mypyc
     # (annoyingly) strips 'em so we need to set it here too.
     help="The uncompromising code formatter.",

src/black/output.py

@@ -59,8 +59,8 @@ def diff(a: str, b: str, a_name: str, b_name: str) -> str:
     """Return a unified diff string between strings `a` and `b`."""
     import difflib
 
-    a_lines = [line for line in a.splitlines(keepends=True)]
+    a_lines = a.splitlines(keepends=True)
-    b_lines = [line for line in b.splitlines(keepends=True)]
+    b_lines = b.splitlines(keepends=True)
     diff_lines = []
     for line in difflib.unified_diff(
         a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5

tests/optional.py

@@ -96,7 +96,7 @@ def pytest_collection_modifyitems(config: "Config", items: "List[Node]") -> None
     enabled_optional_markers = store[ENABLED_OPTIONAL_MARKERS]
 
     for item in items:
-        all_markers_on_test = set(m.name for m in item.iter_markers())
+        all_markers_on_test = {m.name for m in item.iter_markers()}
         optional_markers_on_test = all_markers_on_test & all_possible_optional_markers
         if not optional_markers_on_test or (
             optional_markers_on_test & enabled_optional_markers

tests/test_black.py

@@ -1755,7 +1755,7 @@ def assert_collected_sources(
         report=black.Report(),
         stdin_filename=stdin_filename,
     )
-    assert sorted(list(collected)) == sorted(gs_expected)
+    assert sorted(collected) == sorted(gs_expected)
 
 
 class TestFileCollection: