pytest-qt is not printing the cause of exceptions on python 3

[fabioz]

Consider the code below: The line Error 1 should appear in the stderr, but only Error 2 appears.

This happens because exceptions.format_captured_exceptions is a custom exception printer that doesn't take into account the exception cause.

from pytestqt.qt_compat import qt_api

class MyWidget(qt_api.QWidget):

    def method(self):
        raise RuntimeError('Error 1')

    def event(self, ev):
        called.append(1)
        try:
            self.method()
        finally:
            raise RuntimeError('Error 2')


weak_ref = None
called = []


def test_1(qapp):
    global weak_ref
    w = MyWidget()
    qapp.postEvent(w, qt_api.QEvent(qt_api.QEvent.User))
    qapp.processEvents()
    assert len(called) > 0
    w.deleteLater()

[fabioz]

Changing format_captured_exceptions to the code below seems to fix it for me.

def format_captured_exceptions(exceptions):
    """
    Formats exceptions given as (type, value, traceback) into a string
    suitable to display as a test failure.
    """
    if sys.version_info[0] <= 2:
        message = 'Qt exceptions in virtual methods:\n'
        message += '_' * 80 + '\n'
        for (exc_type, value, tback) in exceptions:
            message += ''.join(traceback.format_tb(tback)) + '\n'
            message += '%s: %s\n' % (exc_type.__name__, value)
            message += '_' * 80 + '\n'
        return message
    else:
        from io import StringIO
        message = StringIO()
        message.write('Qt exceptions in virtual methods:\n')
        message.write('_' * 80 + '\n')
        for (exc_type, value, tback) in exceptions:
            traceback.print_exception(exc_type, value, tback, file=message)
            message.write('_' * 80 + '\n')
        return message.getvalue()

[nicoddemus]

Thanks for the report and sample code @fabioz! I plan to tackle this soon.