Fix error code handling in stubtest with --mypy-config-file (#17629)

This is the first PR in the series of unifing configuration parsing for
different mypy tools.
I would like to have the simple and focused.

mypy/main.py

@@ -19,7 +19,6 @@
     validate_package_allow_list,
 )
 from mypy.error_formatter import OUTPUT_CHOICES
-from mypy.errorcodes import error_codes
 from mypy.errors import CompileError
 from mypy.find_sources import InvalidSourceList, create_source_list
 from mypy.fscache import FileSystemCache
@@ -1336,21 +1335,7 @@ def set_strict_flags() -> None:
 
     validate_package_allow_list(options.untyped_calls_exclude)
 
-    # Process `--enable-error-code` and `--disable-error-code` flags
-    disabled_codes = set(options.disable_error_code)
-    enabled_codes = set(options.enable_error_code)
-
-    valid_error_codes = set(error_codes.keys())
-
-    invalid_codes = (enabled_codes | disabled_codes) - valid_error_codes
-    if invalid_codes:
-        parser.error(f"Invalid error code(s): {', '.join(sorted(invalid_codes))}")
-
-    options.disabled_error_codes |= {error_codes[code] for code in disabled_codes}
-    options.enabled_error_codes |= {error_codes[code] for code in enabled_codes}
-
-    # Enabling an error code always overrides disabling
-    options.disabled_error_codes -= options.enabled_error_codes
+    options.process_error_codes(error_callback=parser.error)
 
     # Validate incomplete features.
     for feature in options.enable_incomplete_feature:

mypy/options.py

@@ -416,6 +416,23 @@ def snapshot(self) -> dict[str, object]:
     def __repr__(self) -> str:
         return f"Options({pprint.pformat(self.snapshot())})"
 
+    def process_error_codes(self, *, error_callback: Callable[[str], Any]) -> None:
+        # Process `--enable-error-code` and `--disable-error-code` flags
+        disabled_codes = set(self.disable_error_code)
+        enabled_codes = set(self.enable_error_code)
+
+        valid_error_codes = set(error_codes.keys())
+
+        invalid_codes = (enabled_codes | disabled_codes) - valid_error_codes
+        if invalid_codes:
+            error_callback(f"Invalid error code(s): {', '.join(sorted(invalid_codes))}")
+
+        self.disabled_error_codes |= {error_codes[code] for code in disabled_codes}
+        self.enabled_error_codes |= {error_codes[code] for code in enabled_codes}
+
+        # Enabling an error code always overrides disabling
+        self.disabled_error_codes -= self.enabled_error_codes
+
     def apply_changes(self, changes: dict[str, object]) -> Options:
         # Note: effects of this method *must* be idempotent.
         new_options = Options()

mypy/stubtest.py

@@ -1941,6 +1941,12 @@ def set_strict_flags() -> None:  # not needed yet
 
         parse_config_file(options, set_strict_flags, options.config_file, sys.stdout, sys.stderr)
 
+    def error_callback(msg: str) -> typing.NoReturn:
+        print(_style("error:", color="red", bold=True), msg)
+        sys.exit(1)
+
+    options.process_error_codes(error_callback=error_callback)
+
     try:
         modules = build_stubs(modules, options, find_submodules=not args.check_typeshed)
     except StubtestFailure as stubtest_failure:

mypy/test/teststubtest.py

@@ -2477,6 +2477,19 @@ def test_config_file(self) -> None:
         output = run_stubtest(stub=stub, runtime=runtime, options=[], config_file=config_file)
         assert output == "Success: no issues found in 1 module\n"
 
+    def test_config_file_error_codes(self) -> None:
+        runtime = "temp = 5\n"
+        stub = "temp = SOME_GLOBAL_CONST"
+        output = run_stubtest(stub=stub, runtime=runtime, options=[])
+        assert output == (
+            "error: not checking stubs due to mypy build errors:\n"
+            'test_module.pyi:1: error: Name "SOME_GLOBAL_CONST" is not defined  [name-defined]\n'
+        )
+
+        config_file = "[mypy]\ndisable_error_code = name-defined\n"
+        output = run_stubtest(stub=stub, runtime=runtime, options=[], config_file=config_file)
+        assert output == "Success: no issues found in 1 module\n"
+
     def test_no_modules(self) -> None:
         output = io.StringIO()
         with contextlib.redirect_stdout(output):