Test inline mypy configuration with more stable mypy option (#138)

* Test inline mypy configuration with more stable mypy option

The mypy configuration --no-strict-optional is discouraged and not much
tested. It caused the test to fail with >=mypy-1.6.0.

Closes #137

* Update flush_errors to match the signature of >=mypy-1.8.0

pytest_mypy_plugins/item.py

@@ -82,7 +82,10 @@ def run_mypy_typechecking(cmd_options: List[str], stdout: TextIO, stderr: TextIO
 
     error_messages = []
 
-    def flush_errors(new_messages: List[str], serious: bool) -> None:
+    # discard filename parameter '_'. Mypy uses it to generate
+    # one junit-xml test entry per file with failures (--junit-format per_file)
+    # and we don't support mypy's --junit-xml option in the first place.
+    def flush_errors(_: str | None, new_messages: List[str], serious: bool) -> None:
         error_messages.extend(new_messages)
         f = stderr if serious else stdout
         try:

pytest_mypy_plugins/tests/test-mypy-config.yml

@@ -1,9 +1,9 @@
 # Also used in `test_explicit_configs.py`
 
-- case: custom_mypy_config_strict_optional_true_set
+- case: custom_mypy_config_disallow_any_explicit_set
+  expect_fail: yes
   main: |
-    from typing import Optional
-    a: Optional[int] = None
-    a + 1  # should not raise an error
+    from typing import Any
+    a: Any = None  # should raise an error
   mypy_config: |
-    strict_optional = false
+    disallow_any_explicit = true