Improve iterable-sequence error message

Author: George-Ogden

mypy_pytest_plugin/iterable_sequence_checker.py

@@ -43,7 +43,7 @@ def _display_error_message(
         self, expected_type: Type, argument_type: Type, context: Context
     ) -> None:
         self.checker.fail(
-            f"Expected {format_type(expected_type, self.checker.options)}, got {format_type(argument_type, self.checker.options)}.",
+            f"Argument has type {format_type(argument_type, self.checker.options)}; expected {format_type(expected_type, self.checker.options)}.",
             context,
             code=ITERABLE_SEQUENCE,
         )

mypy_pytest_plugin/plugin.py

@@ -31,6 +31,7 @@ def __init__(self, options: Options) -> None:
             options.per_module_options.setdefault(module_pattern, {})["ignore_missing_imports"] = (
                 True
             )
+        options.preserve_asts = True
         super().__init__(options)
 
     def get_additional_deps(self, file: MypyFile) -> list[tuple[int, str, int]]:

tests/snapshots/mypy_test/test_check_files/invalid_test/invalid_test.out

@@ -7,9 +7,9 @@ test_samples/invalid_test.py:23: error: Argument 2 has incompatible type "tuple[
 test_samples/invalid_test.py:30: error: Incompatible return value type (got "list[T]", expected "tuple[T, T]")  [return-value]
 test_samples/invalid_test.py:34: error: Argument 1 to "specific_test_case" has incompatible type "str"; expected "int"  [arg-type]
 test_samples/invalid_test.py:34: error: Argument 1 to "specific_test_case" has incompatible type "float"; expected "int"  [arg-type]
-test_samples/invalid_test.py:47: error: Expected "Iterable[Any]", got "list[Any]".  [iterable-sequence]
+test_samples/invalid_test.py:47: error: Argument has type "list[Any]"; expected "Iterable[Any]".  [iterable-sequence]
 test_samples/invalid_test.py:47: note: This still type checks, but could be made more robust by using `iter()`
-test_samples/invalid_test.py:48: error: Expected "Iterable[int]", got "list[int]".  [iterable-sequence]
+test_samples/invalid_test.py:48: error: Argument has type "list[int]"; expected "Iterable[int]".  [iterable-sequence]
 test_samples/invalid_test.py:48: note: This still type checks, but could be made more robust by using `iter()`
 test_samples/invalid_test.py:61: error: Function is missing a type annotation  [no-untyped-def]
 Found 12 errors in 1 file (checked 1 source file)