code: @Test public void gunzipExhaustsSource() throws Exception {
    OkBuffer gzippedSource=new OkBuffer().write(ByteString.decodeHex("1f8b08000000000000004b4c4a0600c241243503000000"));
    ExhaustableSource exhaustableSource=new ExhaustableSource(gzippedSource);
    BufferedSource gunzippedSource=Okio.buffer(new GzipSource(exhaustableSource));
    assertEquals('a',gunzippedSource.readByte());
    assertEquals('b',gunzippedSource.readByte());
    assertEquals('c',gunzippedSource.readByte());
    assertFalse(exhaustableSource.exhausted);
    assertEquals(-1,gunzippedSource.read(new OkBuffer(),1));
    assertTrue(exhaustableSource.exhausted);
  }
  