TST: added failing test for error message check

unittests/test_scanner.py

@@ -37,7 +37,8 @@ import yaml
 from caoscrawler.crawl import Crawler
 from caoscrawler.debug_tree import DebugTree
 from caoscrawler.scanner import (create_converter_registry, load_definition,
-                                 scan_directory, scan_structure_elements)
+                                 scan_directory, scan_structure_elements,
+                                 _load_definition_from_yaml_dict)
 from caoscrawler.structure_elements import (DictElement, DictListElement,
                                             DictTextElement, File)
 from pytest import raises
@@ -316,3 +317,22 @@ def test_record_parents():
             assert rec.parents[0].name == 'Stuff'  # default parent stays if no parent is given on
             # lower levels
             assert len(rec.parents) == 1
+
+
+def test_error_messages():
+    data = {
+        'Experiments': {}
+    }
+
+    broken_yaml = """
+EmptyConverter:
+    """
+    broken_definition = _load_definition_from_yaml_dict(
+        [yaml.load(broken_yaml, Loader=yaml.SafeLoader)])
+
+    converter_registry = create_converter_registry(broken_definition)
+
+    scan_structure_elements(DictElement(name="", value=data), broken_definition, converter_registry)
+
+    # TODO: this already raises the correct error message. This needs to be checked.
+