public String[] getCoderNames(String codecName) {
    String[] coderNames = coderNameMap.get(codecName);
    return coderNames;
  }
@Test
  public void testGetCoderNames() {
    String[] coderNames = CodecRegistry.getInstance().
        getCoderNames(ErasureCodeConstants.RS_CODEC_NAME);
    assertEquals(2, coderNames.length);
    assertEquals(NativeRSRawErasureCoderFactory.CODER_NAME, coderNames[0]);
    assertEquals(RSRawErasureCoderFactory.CODER_NAME, coderNames[1]);

    coderNames = CodecRegistry.getInstance().
        getCoderNames(ErasureCodeConstants.RS_LEGACY_CODEC_NAME);
    assertEquals(1, coderNames.length);
    assertEquals(RSLegacyRawErasureCoderFactory.CODER_NAME,
        coderNames[0]);

    coderNames = CodecRegistry.getInstance().
        getCoderNames(ErasureCodeConstants.XOR_CODEC_NAME);
    assertEquals(2, coderNames.length);
    assertEquals(NativeXORRawErasureCoderFactory.CODER_NAME,
        coderNames[0]);
    assertEquals(XORRawErasureCoderFactory.CODER_NAME, coderNames[1]);
  }