feat: Allow use of OpenSCAP result files in task xccdf_result_to_osca…

…l_ar

Before this commit if you wanted to use result files from OpenSCAP
in the task xccdf_result_to_oscal_ar you had to extract the
`TestResult` element and place it as the root of the XML
document, otherwise the resulting OSCAL document would be
blank. Thus making it impossible to directly use output from
OpenSCAP with the task.

With this commit the task will detect that the root element
is not `TestResult` and then it will find the `TestResult`
element in the XML document. This allows the use of files
created by OpenSCAP using the `--results` and `--results-arf`
switches.

Signed-off-by: Matthew Burket <[email protected]>

trestle/transforms/implementations/xccdf.py

@@ -199,7 +199,7 @@ def inventory_key(self):
     @property
     def ns(self):
         """Derive namespace."""
-        return f'https://ibm.github.io/compliance-trestle/schemas/oscal/ar/{self.scanner_name}'
+        return f'https://ibm.github.io/compliance-trestle/schemas/oscal/ar/{self.scanner_name}'  # noqa: E231
 
 
 class _XccdfResult():
@@ -317,9 +317,14 @@ def _get_result(self, lev1: Element) -> str:
 
     def _parse_xml(self) -> Iterator[RuleUse]:
         """Parse the stringified XML."""
+        ns = {
+            'checklist12': 'http://checklists.nist.gov/xccdf/1.2',
+        }
         results = self.xccdf_xml
         root = ElementTree.fromstring(results, forbid_dtd=True)
         version = self._get_version(root)
+        if _remove_namespace(root.tag) != 'TestResult':
+            root = root.find('.//checklist12:TestResult', ns)
         id_ = self._get_id(root)
         target = self._get_target(root)
         target_type = self._get_target_type(root)