AttributeError: 'ExceptionChainRepr' object has no attribute 'replace'

[sandruczyk]

MacOS 12.4
Python 3.9.12 (system Python)
pytest 7.1.2
pytest-nunit 1.0.0

When executing code with a failing fixture, and a test with 'xfail' mark:

import pytest

@pytest.fixture(scope="class")
def failing_fixture():
    raise Exception("SomeException")

@pytest.mark.usefixtures("failing_fixture")
class TestOne:
    def test_one(self):
        pass

    @pytest.mark.xfail(reason="No reason")
    def test_two(self):
        pytest.fail()

I'm getting an exception:
AttributeError: 'ExceptionChainRepr' object has no attribute 'replace'
nunit_exception.log

But only when executing with '--nunit-xml' option

[polkapolka]

I have re-created the error in a test case.

Traceback (most recent call last):
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/_pytest/pytester.py", line 881, in runpytest_inprocess
    reprec = self.inline_run(*args, **kwargs)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/_pytest/pytester.py", line 847, in inline_run
    ret = pytest.main(list(args), plugins=plugins)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/_pytest/config/__init__.py", line 84, in main
    return config.hook.pytest_cmdline_main(config=config)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/hooks.py", line 286, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/manager.py", line 93, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/manager.py", line 87, in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 208, in _multicall
    return outcome.get_result()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/_pytest/main.py", line 243, in pytest_cmdline_main
    return wrap_session(config, _main)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/_pytest/main.py", line 236, in wrap_session
    session=session, exitstatus=session.exitstatus
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/hooks.py", line 286, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/manager.py", line 93, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/manager.py", line 337, in traced_hookexec
    return outcome.get_result()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 52, in from_call
    result = func()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/manager.py", line 335, in <lambda>
    outcome = _Result.from_call(lambda: oldcall(hook, hook_impls, kwargs))
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/manager.py", line 87, in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 203, in _multicall
    gen.send(outcome)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/_pytest/terminal.py", line 669, in pytest_sessionfinish
    outcome.get_result()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/Users/ppolk/Projects/open_source/pytest-nunit/.tox/py36-pytest46/lib/python3.6/site-packages/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/plugin.py", line 412, in pytest_sessionfinish
    result = NunitTestRun(self).generate_xml()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/nunit.py", line 263, in generate_xml
    tr = self.as_test_run()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/nunit.py", line 257, in as_test_run
    test_suite=self.test_suites,
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/nunit.py", line 237, in test_suites
    for nodeid, module in self.nunitxml.modules.items()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/nunit.py", line 237, in <listcomp>
    for nodeid, module in self.nunitxml.modules.items()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/nunit.py", line 196, in test_cases
    for nodeid, case in self.nunitxml.modules[module].cases.items()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/nunit.py", line 196, in <listcomp>
    for nodeid, case in self.nunitxml.modules[module].cases.items()
  File "/Users/ppolk/Projects/open_source/pytest-nunit/pytest_nunit/attrs2xml.py", line 9, in __init__
    self.text = escape(text, {\'\\x1b\': "&#x1b;"})
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/xml/sax/saxutils.py", line 27, in escape
    data = data.replace("&", "&amp;")',
 "AttributeError: 'ExceptionChainRepr' object has no attribute 'replace'"

[polkapolka]

Understanding this issue.

On these lines, a FailureType is initialized.

pytest-nunit/pytest_nunit/nunit.py

Lines 173 to 176 in 3833c56

	failure=FailureType(
	message=CdataComment(text=case["error"]),
	stack_trace=CdataComment(text=case["stack-trace"]),
	),

The result from case["error"] is expected to be a string value that gets assigned to the text attribute on the CDataComment object.

pytest-nunit/pytest_nunit/attrs2xml.py

Lines 6 to 9 in 3833c56

	class CdataComment(ET.Element):
	def __init__(self, text):
	super(CdataComment, self).__init__("CDATA!")
	self.text = escape(text, {"\x1b": ""})

This testcase instead of returning a string, returns an instance of the object ExceptionChainRepr.

https://github.com/pytest-dev/pytest/blob/3dac833a520cc299c20b7270db87d62412b4119a/src/_pytest/_code/code.py#L1018-L1034

Compare this output from the test_fail testcase with the output from the test_fixture_error testcase.

test_fail testcase

	{'attachments': {'fail.pth': 'desc'},
	 'call-report': <TestReport 'test_attachment_attach_on_any.py::test_fail' when='call' outcome='failed'>,
	 'duration': 0.008849,
	 'error': 'add_nunit_attachment = <bound method '
	          '_NunitNodeReporter.add_attachment of '
	          '<pytest_nunit.plugin._NunitNodeReporter object at 0x7f9a88608320>>\n'
	          '\n'
	          '    def test_fail(add_nunit_attachment):\n'
	          '        add_nunit_attachment("fail.pth", "desc")\n'
	          '>       assert 1 == 0\n'
	          'E       assert 1 == 0\n'
	          'E         -1\n'
	          'E         +0\n'
	          '\n'
	          'test_attachment_attach_on_any.py:6: AssertionError',
	 'idref': 101,
	 'name': 'test_attachment_attach_on_any.py::test_fail',
	 'outcome': 'failed',
	 'path': 'test_attachment_attach_on_any.py',
	 'properties': {'fspath': 'test_attachment_attach_on_any.py',
	                'python-version': '3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, '
	                                  '05:52:31) \n'
	                                  '[GCC 4.2.1 Compatible Apple LLVM 6.0 '
	                                  '(clang-600.0.57)]'},
	 'reason': '',
	 'setup-report': <TestReport 'test_attachment_attach_on_any.py::test_fail' when='setup' outcome='passed'>,
	 'stack-trace': '/private/var/folders/d4/ry1gfxvx6l78_jp31gz9fjk40000gq/T/pytest-of-ppolk/pytest-202/test_attachment_attach_on_any0/test_attachment_attach_on_any.py:6: '
	                'assert 1 == 0',
	 'start': datetime.datetime(2022, 10, 16, 7, 52, 23, 989521),
	 'stderr': '',
	 'stdout': '',
	 'stop': datetime.datetime(2022, 10, 16, 7, 52, 23, 998370),
	 'teardown-report': <TestReport 'test_attachment_attach_on_any.py::test_fail' when='teardown' outcome='passed'>}

test_fixture_error testcase

	{'attachments': None,
	 'call-report': None,
	 'duration': 0,
	 'error': <<class '_pytest._code.code.ExceptionChainRepr'> instance at 7fddf06e5208>,
	 'idref': 101,
	 'name': 'test_failing_fixture.py::TestOne::test_two',
	 'outcome': 'skipped',
	 'path': 'test_failing_fixture.py',
	 'properties': {'fspath': 'test_failing_fixture.py',
	                'python-version': '3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, '
	                                  '05:52:31) \n'
	                                  '[GCC 4.2.1 Compatible Apple LLVM 6.0 '
	                                  '(clang-600.0.57)]'},
	 'reason': '',
	 'setup-report': <TestReport 'test_failing_fixture.py::TestOne::test_two' when='setup' outcome='skipped'>,
	 'stack-trace': '',
	 'start': datetime.datetime(2022, 10, 16, 8, 2, 32, 562000),
	 'stderr': '',
	 'stdout': '',
	 'stop': datetime.datetime(2022, 10, 16, 8, 2, 32, 563996),
	 'teardown-report': <TestReport 'test_failing_fixture.py::TestOne::test_two' when='teardown' outcome='passed'>}

One potential solution, is to coerce the ReprObject into a string by str(case["error"]).

That would set the 'error' value to this.

     '@pytest.fixture(scope="class")\n    def failing_fixture():\n>       raise Exception("SomeException")\nE       Exception: SomeException\n\ntest_failing_fixture.py:5: Exception'

The only concern I have is whether all the other case values for this testcase are captured correctly.
@tonybaloney How would you suggest I solve this issue?

[tonybaloney]

I think it should do the following:

1. if isinstance matches the ExceptionChainRepr type then do special formatting to str if required (does it have a sensible __str__?)
2. else use str() and force the type into string

[polkapolka]

Ok, looked into it some more.

• The ExceptionChainRepr has a sensible __str__.
• The ExceptionChainRepr object also contains the stack trace value. This value is not passed into case["stack-trace"], so I added that.
• Finally, I changed the assertions. The described tests fail due to an exception during the test node setup. This is a return code of 1, see description, and not return code 0 or 3. So the results in stdout from test_one should be Error, and the result in stdout from test_two should be XFail, and the stderr should be empty. These assertions catch the original error.

And are resolved by the latest commit.