message: Test PartialEq for StdError
diff: @@ -353,6 +353,21 @@ mod test {
  assert_eq!(embedded, "Display message: Cannot subtract 5 from 3");
  }
  + #[test]
  + fn implements_partial_eq() {
  + let u1 = StdError::underflow(3, 5);
  + let u2 = StdError::underflow(3, 5);
  + let u3 = StdError::underflow(3, 7);
  + let s1 = StdError::serialize_err("Book", "Content too long");
  + let s2 = StdError::serialize_err("Book", "Content too long");
  + let s3 = StdError::serialize_err("Book", "Title too long");
  + assert_eq!(u1, u2);
  + assert_ne!(u1, u3);
  + assert_ne!(u1, s1);
  + assert_eq!(s1, s2);
  + assert_ne!(s1, s3);
  + }
  +
  #[test]
  fn from_std_str_utf8error_works() {
  let error: StdError = str::from_utf8(b"Hello \xF0\x90\x80World")
  