from os import getcwd
import traceback

from nose.plugins import Plugin


class NoseGNUErrorformatOutput(Plugin):
    """Output tracebacks in GNU errorformat-compatible way.
    """
    name = 'gnuerrorformat'

    def __init__(self):
        super(NoseGNUErrorformatOutput, self).__init__()
        self.cwd = getcwd()

    def formatFailure(self, test, err):
        return self.formatError(test, err)

    def formatError(self, _, err):
        ec, ev, tb = err
        if not isinstance(ev, str):
            ev = traceback.format_exception_only(ec, ev)[0]
        evs = [ev, "-----BEGIN GNU errorformat-----"]
        for (filen, linen, funcn, txt) in traceback.extract_tb(tb):
            if not filen.startswith(self.cwd):
                continue
            filen = filen[len(self.cwd) + 1:]
            evs.append("{}:{:d}:0: {}: {}".format(filen, linen, funcn, txt))
        evs.append("-----END GNU errorformat-----")
        return ec, "\n".join(evs), tb