We should create a set of test cases for 19107 geometry implementations which depend only on GeoAPI interfaces. These test cases can be used for our initial implementation as well as any future implementation. THese tests do not deal with the implementation details of any particular implementation, they just perform function tests on a backing implementation. These tests may have to be abstract, as the means to create geometry objects is by no means defined in 19107. However, a concrete test suite should be made by implementing a single factory interface (perhaps based on CommonFactory) and passing this factory to the suite.