environment/lib/python2.7/site-packages/nose/selector.py
def wantFile(self, file):
        """Is the file a wanted test file?

        The file must be a python source file and match testMatch or
        include, and not match exclude. Files that match ignore are *never*
        wanted, regardless of plugin, testMatch, include or exclude settings.
        """
        # never, ever load files that match anything in ignore
        # (.* _* and *setup*.py by default)
        base = op_basename(file)
        ignore_matches = [ ignore_this for ignore_this in self.ignoreFiles
                           if ignore_this.search(base) ]
        if ignore_matches:
            log.debug('%s matches ignoreFiles pattern; skipped',
                      base) 
            return False
        if not self.config.includeExe and os.access(file, os.X_OK):
            log.info('%s is executable; skipped', file)
            return False
        dummy, ext = op_splitext(base)
        pysrc = ext == '.py'

        wanted = pysrc and self.matches(base) 
        plug_wants = self.plugins.wantFile(file)
        if plug_wants is not None:
            log.debug("plugin setting want %s to %s", file, plug_wants)
            wanted = plug_wants
        log.debug("wantFile %s? %s", file, wanted)
        return wanted
def wantFile(self, file):
        """Is the file a wanted test file?

        The file must be a python source file and match testMatch or
        include, and not match exclude. Files that match ignore are *never*
        wanted, regardless of plugin, testMatch, include or exclude settings.
        """
        # never, ever load files that match anything in ignore
        # (.* _* and *setup*.py by default)
        base = op_basename(file)
        ignore_matches = [ ignore_this for ignore_this in self.ignoreFiles
                           if ignore_this.search(base) ]
        if ignore_matches:
            log.debug('%s matches ignoreFiles pattern; skipped',
                      base) 
            return False
        if not self.config.includeExe and os.access(file, os.X_OK):
            log.info('%s is executable; skipped', file)
            return False
        dummy, ext = op_splitext(base)
        pysrc = ext == '.py'

        wanted = pysrc and self.matches(base) 
        plug_wants = self.plugins.wantFile(file)
        if plug_wants is not None:
            log.debug("plugin setting want %s to %s", file, plug_wants)
            wanted = plug_wants
        log.debug("wantFile %s? %s", file, wanted)
        return wanted
Is the file a wanted test file?

        The file must be a python source file and match testMatch or
        include, and not match exclude. Files that match ignore are *never*
        wanted, regardless of plugin, testMatch, include or exclude settings.