### Question:
RawBackupWriter implements BackupWriter { @Override public void flush() throws IOException { outputStream.flush(); } RawBackupWriter(OutputStream outputStream); @Override void writeBytes(byte[] bytes); @Override void writeChunk(long start, int length); @Override long getBytesWritten(); @Override void flush();  }### Answer:
@Test public void flush_flushesOutputStream() throws Exception { mOutput = mock(ByteArrayOutputStream.class); mWriter = new RawBackupWriter(mOutput); mWriter.flush(); verify(mOutput).flush(); }