From e75cf935acd097ba9ff0f947edfacf38bb4006a1 Mon Sep 17 00:00:00 2001
From: Miguel Cid Flor <cidflor2004@gmail.com>
Date: Tue, 12 May 2026 17:13:34 +0100
Subject: [PATCH 1/3] test(mutation): Added a test to see if the args of
 __add__ mutate after operation

---
 tests/test_general.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tests/test_general.py b/tests/test_general.py
index d41f865..8d8c1d9 100644
--- a/tests/test_general.py
+++ b/tests/test_general.py
@@ -249,6 +249,31 @@ def test_construct_xml(self):
         assert len(case) == 1
         assert case[0].attrib["name"] == "case1"
 
+    def test_add_does_not_mutate_operands(self):
+        text = """<testsuites>
+        <testsuite errors="1" failures="0" hostname="hooch" name="pytest" skipped="1" tests="3" time="0.025"
+        timestamp="2020-02-05T10:52:33.843536">
+        <testcase classname="test_x" file="test_x.py" line="7" name="test_comp_1" time="0.000"/>
+        <testcase classname="test_x" file="test_x.py" line="10" name="test_comp_2" time="0.000">
+        <skipped message="unconditional skip" type="pytest.skip">test_x.py:11: unconditional skip</skipped>
+        <error message="test teardown failure">
+        @pytest.fixture(scope="module") def compb(): yield > raise PermissionError E
+        PermissionError test_x.py:6: PermissionError
+        </error>
+        </testcase>
+        </testsuite>
+        </testsuites>"""
+        a = JUnitXml.fromstring(text)
+        b = JUnitXml.fromstring(text)
+
+        result = a + b
+        assert a.tests == 2, f"Operand 'a' was mutated! tests={a.tests}"
+        assert b.tests == 2, f"Operand 'b' was mutated! tests={b.tests}"
+        assert result.tests == 4, f"Result wrong: tests={result.tests}"
+        _ = a + b
+        assert a.tests == 2, "Operand 'a' emptied after uncaptured +"
+        assert b.tests == 2, "Operand 'b' emptied after uncaptured +"
+
     def test_add(self):
         result1 = JUnitXml()
         suite1 = TestSuite("suite1")

From 4fa96220ccca347dcdbf3dcf0ac5c616e8ee69c1 Mon Sep 17 00:00:00 2001
From: Miguel Cid Flor <cidflor2004@gmail.com>
Date: Tue, 12 May 2026 17:44:09 +0100
Subject: [PATCH 2/3] fix(JUnitXml): After an add the values that were added
 mutated

---
 src/junitparser/junitparser.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/junitparser/junitparser.py b/src/junitparser/junitparser.py
index e4cd9cf..ab34e7a 100644
--- a/src/junitparser/junitparser.py
+++ b/src/junitparser/junitparser.py
@@ -728,9 +728,9 @@ def __len__(self):
     def __add__(self, other):
         result = type(self)()
         for suite in self:
-            result.add_testsuite(suite)
+            result.add_testsuite(deepcopy(suite))
         for suite in other:
-            result.add_testsuite(suite)
+            result.add_testsuite(deepcopy(suite))
         return result
 
     def __iadd__(self, other):

From 88cc9f9758bbafedd6b1c4447a7eba0ccc77e2f7 Mon Sep 17 00:00:00 2001
From: Miguel Cid Flor <cidflor2004@gmail.com>
Date: Tue, 12 May 2026 18:25:10 +0100
Subject: [PATCH 3/3] refactor(JUnitXml): The same problem may be happening in
 other places it makes more sense to put the deepcopy inside the function

---
 src/junitparser/junitparser.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/junitparser/junitparser.py b/src/junitparser/junitparser.py
index ab34e7a..0784786 100644
--- a/src/junitparser/junitparser.py
+++ b/src/junitparser/junitparser.py
@@ -728,9 +728,9 @@ def __len__(self):
     def __add__(self, other):
         result = type(self)()
         for suite in self:
-            result.add_testsuite(deepcopy(suite))
+            result.add_testsuite(suite)
         for suite in other:
-            result.add_testsuite(deepcopy(suite))
+            result.add_testsuite(suite)
         return result
 
     def __iadd__(self, other):
@@ -747,6 +747,7 @@ def __iadd__(self, other):
         return self
 
     def add_testsuite(self, suite: TestSuite):
+        suite = deepcopy(suite)
         """Add a testsuite."""
         for existing_suite in self:
             if existing_suite == suite: