Code review comment for lp:~zorba-coders/zorba/bug-867376

As for the error condition, I've been thinking about it more, and I'm pretty sure that uri:serialize() needs to enforce at least the following rules:

1. You can specify opaque-part, OR some subset of host/port/path/user-info/query. Not both. (Put another way: If opaque-part is specified, then only scheme and fragment may be additionally be specified.)

2. If you specify opaque-part, scheme is required.

3. If you specify a scheme and a path, then the path MUST start with a / character.

I would suggest introducing a zerr:ZURI0001 "malformed URI components" error message for uri:serialize() which is thrown if any of the above rules are broken, as well as some new test cases for each of them. It might be nice to have separate errors for each, I guess - ZURI0001 "cannot specify opaque-part in conjunction with host/port/path/user-info/query", ZURI0002 "scheme required when specifying opaque-part", and ZURI0003 "path component of absolute URI (ie, one with a scheme) must begin with /".