'Returns the list of test_*.py (default) files at or below directory
``dir`` relative to the sympy home directory.'

def get_test_files(self, dir, pat='test_*.py'):

    dir = os.path.join(self._root_dir, convert_to_native_paths([dir])[0])
    g = []
    for (path, folders, files) in os.walk(dir):
        g.extend([os.path.join(path, f) for f in files if fnmatch(f, pat)])
    return sorted([sys_normcase(gi) for gi in g])
