adding easy access to test data for header versions

importer_test_data/__init__.py

 from .__version__ import __version__
 from .data_accessor import TestDataAccessor
-
+from .header_files_accessor import get_header_version_data
 test_data = TestDataAccessor()
+test_data_versions = get_header_version_data()

importer_test_data/header_files_accessor.py

+from os import walk
+from os.path import join, dirname, basename
+
+from .data_accessor import AttrDict
+
+
+def get_header_version_data():
+    """
+    Retrieve the data from the header_versions folder. Data is returned in an attribute dictionary
+    structured as the folder structure of the source folder
+    :return: test_data_header_versions
+    """
+    test_data_header_versions =  AttrDict()
+    folder = join(dirname(__file__), "header_versions")
+
+    for root, _ ,files in walk(folder):
+        if not files: continue
+        test_data_header_versions[basename(root)]=[join(root,f) for f in files]
+
+    return test_data_header_versions
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