message: Add extra intersection test
diff: @@ -394,6 +394,13 @@ mod tests {
  assert_eq!(intersection.doc(), 9);
  assert!(!intersection.advance());
  }
  + {
  + let a = VecPostings::from(vec![1, 3]);
  + let b = VecPostings::from(vec![1, 4]);
  + let c = VecPostings::from(vec![3, 9]);
  + let mut intersection = IntersectionDocSet::from(vec![a, b, c]);
  + assert!(!intersection.advance());
  + }
  }
  