### Question:
DataSourceTransactionManagerHandler extends AbstractTransactionManagerHandler { @Override public void unbindResource() { ConnectionHolder holder = (ConnectionHolder) TransactionSynchronizationManager.unbindResource(transactionManager.getDataSource()); DataSourceUtils.releaseConnection(holder.getConnection(), transactionManager.getDataSource()); } DataSourceTransactionManagerHandler(final PlatformTransactionManager transactionManager); @Override void unbindResource();  }### Answer:
@Test public void assertUnbindResource() { ConnectionHolder holder = mock(ConnectionHolder.class); Connection connection = mock(Connection.class); when(holder.getConnection()).thenReturn(connection); TransactionSynchronizationManager.bindResource(dataSource, holder); dataSourceTransactionManagerHandler.unbindResource(); assertNull(TransactionSynchronizationManager.getResource(dataSource)); }