Argument conversion: Accept any mapping matching TypedDict as-is

The initial fix for #5114 required arguments to be dicts, this change
allows any mapping.

atest/testdata/keywords/type_conversion/unions.py

@@ -1,4 +1,5 @@
 from datetime import date, timedelta
+from collections.abc import Mapping
 from numbers import Rational
 from typing import List, Optional, TypedDict, Union
 
@@ -64,7 +65,10 @@ def union_with_typeddict(argument: Union[XD, None], expected):
     assert argument == eval(expected), '%r != %s' % (argument, expected)
 
 
-def union_with_str_and_typeddict(argument: Union[str, XD], expected):
+def union_with_str_and_typeddict(argument: Union[str, XD], expected, non_dict_mapping=False):
+    if non_dict_mapping:
+        assert isinstance(argument, Mapping) and not isinstance(argument, dict)
+        argument = dict(argument)
     assert argument == eval(expected), '%r != %s' % (argument, expected)
 
 

atest/testdata/keywords/type_conversion/unions.robot

@@ -56,6 +56,8 @@ Union with str and TypedDict
     [Template]    Union with str and TypedDict
     {'x': 1}           "{'x': 1}"
     ${{{'x': 1}}}      {'x': 1}
+    ${{type('NonDictMapping', (collections.abc.Mapping,), {'__getitem__': lambda s, k: {'x': 1}[k], '__iter__': lambda s: iter({'x': 1}), '__len__': lambda s: 1})()}}
+    ...                {'x': 1}    non_dict_mapping=True
     ${{{'bad': 1}}}    "{'bad': 1}"
     ${{{'x': '1'}}}    "{'x': '1'}"
 

src/robot/running/arguments/typeconverters.py

@@ -526,7 +526,7 @@ def handles(cls, type_info: 'TypeInfo') -> bool:
         return type_info.is_typed_dict
 
     def no_conversion_needed(self, value):
-        if not isinstance(value, dict):
+        if not isinstance(value, Mapping):
             return False
         for key in value:
             try: