stubtest: Add a --ignore-keyword-only argument

docs/source/stubtest.rst

@@ -116,6 +116,10 @@ The rest of this section documents the command line interface of stubtest.
 
     Ignore errors for whether an argument should or shouldn't be positional-only
 
+.. option:: --ignore-keyword-only
+
+    Ignore errors for whether an argument should or shouldn't be keyword-only
+
 .. option:: --allowlist FILE
 
     Use file as an allowlist. Can be passed multiple times to combine multiple

mypy/stubtest.py

@@ -135,6 +135,10 @@ def is_positional_only_related(self) -> bool:
         # TODO: This is hacky, use error codes or something more resilient
         return "leading double underscore" in self.message
 
+    def is_keyword_only_related(self) -> bool:
+        """Whether or not the error is for something being (or not being) keyword-only."""
+        return "is not keyword-only" in self.message
+
     def get_description(self, concise: bool = False) -> str:
         """Returns a description of the error.
 
@@ -1864,6 +1868,7 @@ class _Arguments:
     concise: bool
     ignore_missing_stub: bool
     ignore_positional_only: bool
+    ignore_keyword_only: bool
     allowlist: list[str]
     generate_allowlist: bool
     ignore_unused_allowlist: bool
@@ -1940,6 +1945,8 @@ def set_strict_flags() -> None:  # not needed yet
                 continue
             if args.ignore_positional_only and error.is_positional_only_related():
                 continue
+            if args.ignore_keyword_only and error.is_keyword_only_related():
+                continue
             if error.object_desc in allowlist:
                 allowlist[error.object_desc] = True
                 continue
@@ -2017,6 +2024,11 @@ def parse_options(args: list[str]) -> _Arguments:
         action="store_true",
         help="Ignore errors for whether an argument should or shouldn't be positional-only",
     )
+    parser.add_argument(
+        "--ignore-keyword-only",
+        action="store_true",
+        help="Ignore errors for whether an argument should or shouldn't be keyword-only",
+    )
     parser.add_argument(
         "--allowlist",
         "--whitelist",

mypy/test/teststubtest.py

@@ -2263,6 +2263,11 @@ def test_ignore_flags(self) -> None:
         )
         assert output == "Success: no issues found in 1 module\n"
 
+        output = run_stubtest(
+            stub="def f(*, a): ...", runtime="def f(a): pass", options=["--ignore-keyword-only"]
+        )
+        assert output == "Success: no issues found in 1 module\n"
+
     def test_allowlist(self) -> None:
         # Can't use this as a context because Windows
         allowlist = tempfile.NamedTemporaryFile(mode="w+", delete=False)