TST: added test for creating File entities

unittests/cfood_simple_file.yml

+# This is only a scifolder test cfood with a limited functionality.
+# The full scifolder cfood will be developed here:
+# https://gitlab.indiscale.com/caosdb/src/crawler-cfoods/scifolder-cfood
+
+---
+metadata:
+  crawler-version: 0.3.1
+---
+Definitions:
+  type: Definitions
+  #include "description.yml"
+
+Data:  # name of the converter
+  type: Directory
+  match: (.*)
+  subtree:
+    DataAnalysis:  # name of the converter
+      type: Directory
+      match: DataAnalysis
+      subtree: &template
+        project_dir:  # name of the first subtree element which is a converter
+          type: Directory
+          match: ((?P<date>[0-9]{4,4})_)?(?P<identifier>.*)
+          records:
+            Project:  # this is an identifiable in this case
+              parents:
+              - Project  # not needed as the name is equivalent
+              date: $date
+              identifier: ${identifier}
+      
+          subtree:
+            measurement:  # new name for folders on the 3rd level
+              type: Directory
+              match: (?P<date>[0-9]{4,4}-[0-9]{2,2}-[0-9]{2,2})(_(?P<identifier>.*))?
+              records:
+                Measurement:
+                  date: $date
+                  identifier: $identifier
+                  project: $Project
+              subtree:
+                README:
+                  type: SimpleFile # this is a subclass of converter File
+                  # function signature: GeneralStore, StructureElement
+                  # preprocessors: custom.caosdb.convert_values
+                  match: ^README\.md$
+                  # how to make match case insensitive?
+                  records:
+                    TestFile:
+                      path: $README
+                      file: $README
+                      role: File
+

unittests/test_scanner.py

@@ -332,3 +332,12 @@ def test_new_debug_tree():
         "unittests/test_directories/examples_article")
     assert len(new_debug_tree[0]["matching_converters"]) == 1  # exactly one matches
     assert len(new_debug_tree[0]["matching_converters"][0]["subtree"]) == 4
+
+
+def test_new_debug_tree_files():
+    new_debug_tree = []
+    scan_directory(UNITTESTDIR / "test_directories" / "examples_article",
+                   UNITTESTDIR / "cfood_simple_file.yml",
+                   new_debug_tree=new_debug_tree)
+    assert True  # The only purpose of this test is to check whether
+                 # it is possible to create a File entity and set a path.