@Test
public void testFormatBackTraceUnknown() {

    Exception e = new IOException("Fake I/O");
    e.setStackTrace(new StackTraceElement[]{
        new StackTraceElement(CompactFormatterTest.class.getName(),
        "testFormatBackTrace", null, -2)});
    assertNotNull(e.getMessage(), e.getMessage());
    CompactFormatter cf = new CompactFormatter();
    LogRecord record = new LogRecord(Level.SEVERE, "");
    record.setThrown(e);
    String result = cf.formatBackTrace(record);
    assertTrue(result, result.startsWith("CompactFormatterTest"));
    assertTrue(result, result.contains("testFormatBackTrace"));
}