code: @Test public void shouldGzipWhenGzipSupported() throws Exception {
    markGzipAsAllowed();
    final String content="sampleContent";
    final InputStream sourceStream=new ByteArrayInputStream(content.getBytes());
    final ByteArrayOutputStream targetStream=new ByteArrayOutputStream();
    when(mockRequest.getInputStream()).thenReturn(new DelegatingServletInputStream(sourceStream));
    when(mockResponse.getOutputStream()).thenReturn(new DelegatingServletOutputStream(targetStream));
    victim.doFilter(mockRequest,mockResponse,mockFilterChain);
    verify(mockFilterChain,Mockito.never()).doFilter(mockRequest,mockResponse);
    verify(mockFilterChain,Mockito.times(1)).doFilter(Mockito.eq(mockRequest),Mockito.any(HttpServletResponse.class));
    final InputStream ungzippedStream=new GZIPInputStream(new ByteArrayInputStream(targetStream.toByteArray()));
    assertEquals(content,IOUtils.toString(ungzippedStream));
  }
  