    @Test
    public void configString() {

        assertEquals("foo", MetricName.valueOf("foo").configString().toString());
        assertEquals("'99'", MetricName.valueOf("99").configString().toString());
        assertEquals("'\\r'", MetricName.valueOf("\r").configString().toString());
        assertEquals("'3'.'14159'", MetricName.valueOf("3", "14159").configString().toString());
        assertEquals("''", MetricName.valueOf("").configString().toString());
    }