message: Be more specific about how panics should occur in counter tests
diff: @@ -96,7 +96,7 @@ mod tests {
  }
  #[test]
  - #[should_panic]
  + #[should_panic(expected = "tried to decrease in-flight to negative value")]
  fn panics_on_underflow() {
  let mut kc = KeyedCounter::new();
  assert_eq!(kc.inc(&'a'), 1);
  @@ -105,7 +105,7 @@ mod tests {
  }
  #[test]
  - #[should_panic]
  + #[should_panic(expected = "tried to decrease in-flight to negative value")]
  fn panics_on_immediate_underflow() {
  let mut kc = KeyedCounter::new();
  kc.dec(&'a');
  