Escape skip reason in junitxml (#11842)

Co-authored-by: Bruno Oliveira <bruno@soliv.dev>

changelog/11842.bugfix.rst

@@ -0,0 +1 @@
+Properly escape the ``reason`` of a :ref:`skip <pytest.mark.skip ref>` mark when writing JUnit XML files.

src/_pytest/junitxml.py

@@ -248,7 +248,9 @@ def append_skipped(self, report: TestReport) -> None:
                 skipreason = skipreason[9:]
             details = f"{filename}:{lineno}: {skipreason}"
 
-            skipped = ET.Element("skipped", type="pytest.skip", message=skipreason)
+            skipped = ET.Element(
+                "skipped", type="pytest.skip", message=bin_xml_escape(skipreason)
+            )
             skipped.text = bin_xml_escape(details)
             self.append(skipped)
             self.write_captured_output(report)

testing/test_junitxml.py

@@ -1653,6 +1653,23 @@ def test_skip():
     snode.assert_attr(message="1 <> 2")
 
 
+def test_bin_escaped_skipreason(pytester: Pytester, run_and_parse: RunAndParse) -> None:
+    """Escape special characters from mark.skip reason (#11842)."""
+    pytester.makepyfile(
+        """
+        import pytest
+        @pytest.mark.skip("\33[31;1mred\33[0m")
+        def test_skip():
+            pass
+    """
+    )
+    _, dom = run_and_parse()
+    node = dom.find_first_by_tag("testcase")
+    snode = node.find_first_by_tag("skipped")
+    assert "#x1B[31;1mred#x1B[0m" in snode.text
+    snode.assert_attr(message="#x1B[31;1mred#x1B[0m")
+
+
 def test_escaped_setup_teardown_error(
     pytester: Pytester, run_and_parse: RunAndParse
 ) -> None: