# Source code for pytestqt.exceptions

    from contextlib import contextmanager
    import sys
    import traceback
    import pytest

    @contextmanager
    def capture_exceptions():
        """
        Context manager that captures exceptions that happen insides its context,
        and returns them as a list of (type, value, traceback) after the
        context ends.
        """
        manager = _QtExceptionCaptureManager()
        manager.start()
        try:
            yield manager.exceptions
        finally:
            manager.finish()

    class _QtExceptionCaptureManager(object):
        """
        Manages exception capture context.
        """

        def __init__(self):
            self.old_hook = None
            self.exceptions = []

        def start(self):
            """Start exception capturing by installing a hook into sys.excepthook
            that records exceptions received into ``self.exceptions``.
            """
            def hook(type_, value, tback):
                self.exceptions.append((type_, value, tback))
                sys.stderr.write(format_captured_exceptions([(type_, value, tback)]))

            self.old_hook = sys.excepthook
            sys.excepthook = hook

        def finish(self):
            """Stop exception capturing, restoring the original hook.

            Can be called multiple times.
            """
            if self.old_hook is not None:
                sys.excepthook = self.old_hook
                self.old_hook = None

        def fail_if_exceptions_occurred(self, when):
            """calls pytest.fail() with an informative message if exceptions
            have been captured so far. Before pytest.fail() is called, also
            finish capturing.
            """
            if self.exceptions:
                self.finish()
                exceptions = self.exceptions
                self.exceptions = []
                prefix = '%s ERROR: ' % when
                pytest.fail(prefix + format_captured_exceptions(exceptions),
                            pytrace=False)

    def format_captured_exceptions(exceptions):
        """
        Formats exceptions given as (type, value, traceback) into a string
        suitable to display as a test failure.
        """
        message = 'Qt exceptions in virtual methods:\n'
        message += '_' * 80 + '\n'
        for (exc_type, value, tback) in exceptions:
            message += ''.join(traceback.format_exception(exc_type, value, tback)) + '\n'
            message += '_' * 80 + '\n'
        return message

    def _is_exception_capture_enabled(item):
        """returns if exception capture is disabled for the given test item.
        """
        disabled = item.get_marker('qt_no_exception_capture') or \
                   item.config.getini('qt_no_exception_capture')
        return not disabled

    class TimeoutError(Exception):
        """
        .. versionadded:: 2.1

        Exception thrown by :class:`pytestqt.qtbot.QtBot` methods.

        .. note::
            In versions prior to ``2.1``, this exception was called ``SignalTimeoutError``.
            An alias is kept for backward compatibility.
        """
        pass

    # backward compatibility alias
    SignalTimeoutError = TimeoutError