version(unittest) string testFilename(string file = __FILE__, size_t line = __LINE__)
{
    import std.conv : text;
    import std.path : baseName;

    // Non-ASCII characters can't be used because of snn.lib @@@BUG8643@@@
    version(DIGITAL_MARS_STDIO)
        return text("deleteme-.", baseName(file), ".", line);
    else

        // filename intentionally contains non-ASCII (Russian) characters
        return text("deleteme-детка.", baseName(file), ".", line);
}