Allow empty YAML entity lists

launch_yaml/launch_yaml/entity.py

@@ -123,7 +123,7 @@ def get_attr(
         self.__read_keys.add(name)
         data = self.__element[name]
         if check_is_list_entity(data_type):
-            if isinstance(data, list) and isinstance(data[0], dict):
+            if isinstance(data, list) and (not data or isinstance(data[0], dict)):
                 return [Entity(child, name) for child in data]
             raise TypeError(
                 "Attribute '{}' of Entity '{}' expected to be a list of dictionaries.".format(

launch_yaml/test/launch_yaml/test_include.py

@@ -61,5 +61,24 @@ def test_include():
     assert ls.context.launch_configurations['baz'] == 'BAZ'
 
 
+def test_include_with_empty_argument_lists():
+    """Parse an include action with explicitly empty argument lists."""
+    path = (Path(__file__).parent / 'executable.yaml').as_posix()
+    yaml_file = textwrap.dedent(
+        """\
+        launch:
+        - include:
+            file: '{}'
+            arg: []
+            let: []
+        """.format(path)
+    )
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+    ld = parser.parse_description(root_entity)
+
+    include = ld.entities[0]
+    assert include.launch_arguments == ()
+
+
 if __name__ == '__main__':
     test_include()