I have been writing lots of software for the OpenStreetMap project and there is always one problem: How to test it? There is a huge variety of data in OSM, every conceivable way of tagging, every way of getting the data slightly (or not so slightly) wrong, will sooner or later appear. We need to test file formats, OSM objects syntax and semantic, changing data, cases with failing referential integrity or invalid geometries and much much more. But just coming up with all those test cases is a huge task and implementing those tests is even more work.

In October 2010 I introduced taginfo. Since then I have updated it occasionally and added new functions. And over time it has become part of the “OSM landscape”.