feat: implement github format

setup.cfg

@@ -52,6 +52,7 @@ flake8.extension =
     W = flake8.plugins.pycodestyle:pycodestyle_physical
 flake8.report =
     default = flake8.formatting.default:Default
+    github = flake8.formatting.default:GitHub
     pylint = flake8.formatting.default:Pylint
     quiet-filename = flake8.formatting.default:FilenameOnly
     quiet-nothing = flake8.formatting.default:Nothing

src/flake8/formatting/default.py

@@ -78,6 +78,16 @@ class Pylint(SimpleFormatter):
     error_format = "%(path)s:%(row)d: [%(code)s] %(text)s"
 
 
+class GitHub(SimpleFormatter):
+    """GitHub formatter for Flake8."""
+
+    error_format = (
+        "::error title=Flake8 %(code)s,file=%(path)s,"
+        "line=%(row)d,col=%(col)d,endLine=%(row)d,endColumn=%(col)d"
+        "::%(code)s %(text)s"
+    )
+
+
 class FilenameOnly(SimpleFormatter):
     """Only print filenames, e.g., flake8 -q."""
 

tests/integration/test_main.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 
 import json
 import os
+import re
 import sys
 from unittest import mock
 
@@ -396,5 +397,8 @@ def test_format_option_help(capsys):
         cli.main(["--help"])
 
     out, err = capsys.readouterr()
-    assert "(default, pylint, quiet-filename, quiet-nothing)" in out
+    assert (
+        "(default, github, pylint, quiet-filename, quiet-nothing)"
+        in re.sub(re.compile(r"\n\s*"), "", out)  # noqa: E501
+    )
     assert err == ""

tests/unit/plugins/reporter_test.py

@@ -8,6 +8,7 @@ import pytest
 from flake8.formatting import default
 from flake8.plugins import finder
 from flake8.plugins import reporter
+from flake8.violation import Violation
 
 
 def _opts(**kwargs):
@@ -17,6 +18,18 @@ def _opts(**kwargs):
     return argparse.Namespace(**kwargs)
 
 
+@pytest.fixture
+def violation():
+    return Violation(
+        code="E501",
+        filename="test/test1.py",
+        line_number=1,
+        column_number=2,
+        text="line too long (124 > 79 characters)",
+        physical_line=None,
+    )
+
+
 @pytest.fixture
 def reporters():
     def _plugin(name, cls):
@@ -35,6 +48,7 @@ def reporters():
     return {
         "default": _plugin("default", default.Default),
         "pylint": _plugin("pylint", default.Pylint),
+        "github": _plugin("github", default.GitHub),
         "quiet-filename": _plugin("quiet-filename", default.FilenameOnly),
         "quiet-nothing": _plugin("quiet-nothing", default.Nothing),
     }
@@ -57,9 +71,27 @@ def test_make_formatter_very_quiet(reporters, quiet):
     assert isinstance(ret, default.Nothing)
 
 
-def test_make_formatter_custom(reporters):
-    ret = reporter.make(reporters, _opts(format="pylint"))
-    assert isinstance(ret, default.Pylint)
+@pytest.mark.parametrize(
+    "format_input, expected_formatter_class, error_str",
+    [
+        (
+            "pylint",
+            default.Pylint,
+            "test/test1.py:1: [E501] line too long (124 > 79 characters)",
+        ),
+        (
+            "github",
+            default.GitHub,
+            "::error title=Flake8 E501,file=test/test1.py,line=1,col=2,endLine=1,endColumn=2::E501 line too long (124 > 79 characters)",  # noqa: E501
+        ),
+    ],
+)
+def test_make_formatter_custom(
+    reporters, violation, format_input, expected_formatter_class, error_str
+):
+    ret = reporter.make(reporters, _opts(format=format_input))
+    assert isinstance(ret, expected_formatter_class)
+    assert ret.format(violation) == error_str
 
 
 def test_make_formatter_format_string(reporters, caplog):