code: @Test public void should_throw_error_wrapping_catched_IOException() throws IOException {
    IOException cause=new IOException();
    when(diff.diff(path.toFile(),expected,charset)).thenThrow(cause);
    when(nioFilesWrapper.exists(path)).thenReturn(true);
    when(nioFilesWrapper.isReadable(path)).thenReturn(true);
    try {
      paths.assertHasContent(someInfo(),path,expected,charset);
      failBecauseExceptionWasNotThrown(FilesException.class);
    }
   catch (  FilesException e) {
      assertThat(e.getCause()).isSameAs(cause);
    }
  }
  