add tests

[iwakeh]

It's important to add test immediately or even before coding.

[tomlurge]

this could be a major undertaking. can you give more specific advice?

[iwakeh]

For a start I would suggest creating tests for the normal import of valid descriptors of each type.
And, tests that verify the behavior of an import of the bridge descriptor the not yet implemented tunnel-field and maybe other 'troublesome' input.
In addition, tests for what is supposed to happen for multiple imports of the same descriptor(s), and tests for the decisions made on other issues that came up so far.

All these will be very useful right now, i.e., for the current development process.

You could also use tests for debugging and investigating #7.