Better detection of iterables. Fixes robotframework#3547.

pekkaklarck · pekkaklarck · commit cf2aa3b97373 · 2020-09-15T10:19:15.000+03:00
diff --git a/src/robot/utils/robottypes2.py b/src/robot/utils/robottypes2.py
@@ -13,7 +13,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-from collections import Mapping, MutableMapping, Sequence
+from collections import Iterable, Mapping, MutableMapping, Sequence
 from UserDict import UserDict
 from UserString import UserString
 from types import ClassType, NoneType
@@ -56,14 +56,7 @@ def is_list_like(item):
     if isinstance(item, (str, unicode, bytes, bytearray, UserString, String,
                          file)):
         return False
-    try:
-        iter(item)
-    except RERAISED_EXCEPTIONS:
-        raise
-    except:
-        return False
-    else:
-        return True
+    return isinstance(item, (Iterable, UserDict))
 
 
 def is_dict_like(item):
diff --git a/src/robot/utils/robottypes3.py b/src/robot/utils/robottypes3.py
@@ -13,7 +13,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-from collections.abc import Mapping, MutableMapping, Sequence
+from collections.abc import Iterable, Mapping, MutableMapping, Sequence
 from collections import UserString
 from io import IOBase
 
@@ -53,14 +53,7 @@ def is_pathlike(item):
 def is_list_like(item):
     if isinstance(item, (str, bytes, bytearray, UserString, IOBase)):
         return False
-    try:
-        iter(item)
-    except RERAISED_EXCEPTIONS:
-        raise
-    except:
-        return False
-    else:
-        return True
+    return isinstance(item, Iterable)
 
 
 def is_dict_like(item):
diff --git a/utest/utils/test_robottypes.py b/utest/utils/test_robottypes.py
@@ -84,13 +84,19 @@ def test_files_are_not_list_like(self):
             assert_equal(is_list_like(f), False)
         assert_equal(is_list_like(f), False)
 
-    def test_object_raising_exception_are_not_list_like(self):
-        class O(object):
+    def test_iter_makes_object_iterable_regardless_implementation(self):
+        class Example(object):
             def __iter__(self):
                 1/0
-        assert_equal(is_list_like(O()), False)
+        assert_equal(is_list_like(Example()), True)
 
-    def test_other_iterables_are_list_like(self):
+    def test_only_getitem_does_not_make_object_iterable(self):
+        class Example(object):
+            def __getitem__(self, item):
+                return "I'm not iterable!"
+        assert_equal(is_list_like(Example()), False)
+
+    def test_iterables_in_general_are_list_like(self):
         for thing in [[], (), set(), xrange(1), generator(), array('i'), UserList()]:
             assert_equal(is_list_like(thing), True, thing)
 
