### Question:
BackendMessageDecoder { public AbstractBackendMessage decode(DecoderInputStream input, boolean block) throws IOException { if (!input.markSupported() && !block) { throw new IllegalArgumentException("Non-blocking decoding requires an InputStream that supports marking"); } input.mark(Integer.MAX_VALUE); AbstractBackendMessage message = null; try { message = doDecode(input, block); } finally { if (message == null) { input.reset(); } } return message; } BackendMessageDecoder(ConnectionState connectionState); AbstractBackendMessage decode(DecoderInputStream input, boolean block);  }### Answer:
@Test public void testDecodeAuthenticationRequest() throws Exception { AuthenticationMessage message = decode(AUTHENTICATION_REQUEST); Assert.assertEquals(message.getType(), BackendMessageType.AUTHENTICATION); Assert.assertEquals(message.getAuthenticaitonType(), AuthenticationType.MD5_PASSWORD); Assert.assertEquals(message.getData(), decodeHex("81368E2A")); }
@Test public void testDecodeAthenticationSuccess() throws Exception { AuthenticationMessage message = decode(AUTHENTICATION_SUCCESS); Assert.assertEquals(message.getType(), BackendMessageType.AUTHENTICATION); Assert.assertEquals(message.getAuthenticaitonType(), AuthenticationType.OK); }
@Test public void testParameterStatus() throws Exception { ParameterMessage message = decode(PARAMETER_CLIENT_ENCODING); Assert.assertEquals(message.getType(), BackendMessageType.PARAMETER_STATUS); Assert.assertEquals(message.getVariable(), ConfigurationVariable.CLIENT_ENCODING); Assert.assertEquals(message.getValue(), "UNICODE"); }
@Test public void testBackendKey() throws Exception { KeyMessage message = decode(KEY); Assert.assertEquals(message.getType(), BackendMessageType.KEY); Assert.assertEquals(message.getPid(), 22008); Assert.assertEquals(message.getKey(), 1679401028); }
@Test public void testReadyForQuery() throws Exception { ReadyMessage message = decode(READY_FOR_QUERY); Assert.assertEquals(message.getType(), BackendMessageType.READY_FOR_QUERY); Assert.assertEquals(message.getStatus(), Status.IDLE); }
@Test public void rowDescription() throws Exception { RowDescriptionMessage message = decode(ROW_DESCRIPTION); Assert.assertEquals(message.getType(), BackendMessageType.ROW_DESCRIPTION); Assert.assertEquals(message.getFields().length, 1); PgField field = message.getFields()[0]; Assert.assertEquals(field.getColumnLabel(), "id"); Assert.assertEquals(field.getColumnType(), Type.INTEGER); }