Check invalid operations for -k

`KeywordMapping` returns a bool on lookup which when passed to eval
fail on certain operations such as index access and attribute access.
Check has been added to raise a UsageError if such operations are passed
to -k

Author: gdhameeja

src/_pytest/mark/legacy.py

@@ -92,6 +92,7 @@ def matchkeyword(colitem, keywordexpr):
     any item, as well as names directly assigned to test functions.
     """
     mapping = KeywordMapping.from_item(colitem)
+    _check_invalid_operations(keywordexpr)
     if " " not in keywordexpr:
         # special case to allow for simple "-k pass" and "-k 1.3"
         return mapping[keywordexpr]
@@ -108,3 +109,13 @@ def matchkeyword(colitem, keywordexpr):
         return eval(keywordexpr, {}, mapping)
     except SyntaxError:
         raise UsageError("Wrong expression passed to '-k': {}".format(keywordexpr))
+    except TypeError:
+        raise UsageError("Attribute access and indexing is not allowed in '-k'")
+
+
+def _check_invalid_operations(keywordexpr):
+    """`KeywordMapping` returns boolean on lookups, hence certain
+    operations fail in eval, like index access, attribute access"""
+    msg = "Attribute access and indexing is not allowed in '-k'"
+    if "." in keywordexpr or '[' in keywordexpr:
+        raise UsageError(msg)