tests: more general testing #58
Description
This from @vincefn in the comments to #13.
- regarding identity testing, a few years back I added an int_ptr() method precisely to start addressing this
- I did not go all the way and add the equality operator because I did not have the time to test it for all classes (and possible corner cases), but it should now be easy to add. Feel free to add it
for equality that's more complicated, and it probably needs implementation upstream. One cheap (programming-wise) implementation would be to test for the equality of the XMLOutput for all important classes, but that would not be efficient, and may fail for some corner cases (e.g. ordering of atoms and components..)
The issue is to implement this.