@Test
public void abbreviate() throws IOException {

    File in = FileUtil.makeFileGz("time,sensor,x,y,z\n,gps,1,2,3\n,alt,4,5,6\n,grv,7,8,9");
    File out = File.createTempFile("abbrv-out", ".csv");
    TrackAbbrv.abbreviate(in, out);
    assertEquals(40, out.length());
}