junitxml: Fix double system-out tags per testcase

In the xml report we now have two occurences for the system-out tag if
the testcase writes to stdout both on call and teardown and fails in
teardown.
This behaviour is against the xsd.
This patch makes sure that the system-out section exists only
once per testcase.

_pytest/junitxml.py

@@ -119,7 +119,7 @@ def _add_simple(self, kind, message, data=None):
         node = kind(data, message=message)
         self.append(node)
 
-    def _write_captured_output(self, report):
+    def write_captured_output(self, report):
         for capname in ('out', 'err'):
             content = getattr(report, 'capstd' + capname)
             if content:
@@ -128,7 +128,6 @@ def _write_captured_output(self, report):
 
     def append_pass(self, report):
         self.add_stats('passed')
-        self._write_captured_output(report)
 
     def append_failure(self, report):
         # msg = str(report.longrepr.reprtraceback.extraline)
@@ -147,7 +146,6 @@ def append_failure(self, report):
             fail = Junit.failure(message=message)
             fail.append(bin_xml_escape(report.longrepr))
             self.append(fail)
-        self._write_captured_output(report)
 
     def append_collect_error(self, report):
         # msg = str(report.longrepr.reprtraceback.extraline)
@@ -165,7 +163,6 @@ def append_error(self, report):
             msg = "test setup failure"
         self._add_simple(
             Junit.error, msg, report.longrepr)
-        self._write_captured_output(report)
 
     def append_skipped(self, report):
         if hasattr(report, "wasxfail"):
@@ -180,7 +177,7 @@ def append_skipped(self, report):
                 Junit.skipped("%s:%s: %s" % (filename, lineno, skipreason),
                               type="pytest.skip",
                               message=skipreason))
-        self._write_captured_output(report)
+        self.write_captured_output(report)
 
     def finalize(self):
         data = self.to_xml().unicode(indent=0)
@@ -345,6 +342,8 @@ def pytest_runtest_logreport(self, report):
             reporter.append_skipped(report)
         self.update_testcase_duration(report)
         if report.when == "teardown":
+            reporter = self._opentestcase(report)
+            reporter.write_captured_output(report)
             self.finalize(report)
 
     def update_testcase_duration(self, report):

testing/test_junitxml.py

@@ -557,6 +557,25 @@ def test_function(arg):
         systemout = pnode.find_first_by_tag("system-err")
         assert "hello-stderr" in systemout.toxml()
 
+    def test_avoid_double_stdout(self, testdir):
+        testdir.makepyfile("""
+            import sys
+            import pytest
+
+            @pytest.fixture
+            def arg(request):
+                yield
+                sys.stdout.write('hello-stdout teardown')
+                raise ValueError()
+            def test_function(arg):
+                sys.stdout.write('hello-stdout call')
+        """)
+        result, dom = runandparse(testdir)
+        node = dom.find_first_by_tag("testsuite")
+        pnode = node.find_first_by_tag("testcase")
+        systemout = pnode.find_first_by_tag("system-out")
+        assert "hello-stdout call" in systemout.toxml()
+        assert "hello-stdout teardown" in systemout.toxml()
 
 def test_mangle_test_address():
     from _pytest.junitxml import mangle_test_address