fix instance comparison of extensions (Draegerwerk#310)

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## Types of changes
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- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
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## Checklist:
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- [x] I have updated the [changelog](../CHANGELOG.md) accordingly.
- [x] I have added tests to cover my changes.

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to the sdc11073 module will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- fixed a bug where comparing `ExtensionLocalValue` would fail when using the `!=` operator [#305](https://github.com/Draegerwerk/sdc11073/issues/305)
+
 ## [2.0.0a7] - 2024-01-04
 
 ### Added

src/sdc11073/xml_types/xml_structure.py

@@ -826,7 +826,7 @@ def update_xml_value(self, instance: Any, node: xml_utils.LxmlElement):
 
 
 def _compare_extension(left: xml_utils.LxmlElement, right: xml_utils.LxmlElement) -> bool:
-    # xml comparison
+    # SDPi R0019 and R0020 forbid the usage of XML mixed content or xml schema qname type in extensions
     try:
         if left.tag != right.tag:  # compare expanded names
             return False
@@ -860,6 +860,9 @@ def __eq__(self, other: Sequence) -> bool:
             return False
         return all(self.__class__.compare_method(left, right) for left, right in zip(self, other))
 
+    def __ne__(self, other):
+        return not self == other
+
 
 class ExtensionNodeProperty(_ElementBase):
     """Represents an ext:Extension Element that contains 0...n child elements of any kind.

tests/test_pmtypes.py

@@ -338,7 +338,6 @@ def my_generator():
         inst3.ExtExtension = my_generator()
         self.assertEqual(inst2.ExtExtension, inst3.ExtExtension)
 
-
     def test_mixed_content_is_ignored(self):
         xml1 = fromstring(b"""<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <ext:Extension xmlns:ext="http://standards.ieee.org/downloads/11073/11073-10207-2017/extension"
@@ -356,3 +355,32 @@ def test_mixed_content_is_ignored(self):
         inst1 = xml_structure.ExtensionLocalValue([xml1])
         inst2 = xml_structure.ExtensionLocalValue([xml2])
         self.assertEqual(inst1, inst2)
+
+    def test_operators_of_extension_local_value(self):
+        xml1 = fromstring(b"""
+            <ext:Extension xmlns:ext="__ExtensionPoint__">
+                <foo someattr="somevalue"/>
+            </ext:Extension>
+        """)  # noqa: S320
+        xml2 = fromstring(b"""
+            <ext:Extension xmlns:ext="__ExtensionPoint__">
+                <foo someattr="somevalue"/>
+            </ext:Extension>
+        """)  # noqa: S320
+        inst1 = xml_structure.ExtensionLocalValue([xml1])
+        inst2 = xml_structure.ExtensionLocalValue([xml2])
+        self.assertEqual(inst1, inst2)
+        self.assertTrue(inst1 == inst1)
+        self.assertFalse(inst1 != inst1)
+        self.assertTrue(inst1 == inst2)
+        self.assertFalse(inst1 != inst2)
+
+        xml2 = fromstring(b"""
+            <ext:Extension xmlns:ext="__ExtensionPoint__">
+                <bar anotherattr="differentvalue"/>
+            </ext:Extension>
+        """)  # noqa: S320
+        inst2 = xml_structure.ExtensionLocalValue([xml2])
+        self.assertNotEqual(inst1, inst2)
+        self.assertFalse(inst1 == inst2)
+        self.assertTrue(inst1 != inst2)