Develop approach to run PROJ.4 unit tests

[dr-jts]

It would be great to be able to run all or most of the PROJ.4 unit tests against Proj4J.

It appears that the current testing framework for PROJ.4 uses a custom utility called GIE. This reads a custom format originating in a test utility called GIGS. There are a LOT of unit tests.

Possible approaches:

1. Port the unit tests to a format which Proj4J can run. This should be a declarative format, for maximum usabliy and ease of maintenance. The current MetaCRS CSV format is too hard to work with IMHO - a better format should be devised. This will also require a transpiler from the GIE format to the Proj4J format.

2. Develop a test runner that can handle the GIGS/GIE format directly. Hopefully this won't be too hard. The advantage here is that it will be easier to keep the tests in synch with PROJ.4

Note that it is very likely that not all PROJ4 tests will run in Proj4J, due to differences in supported functionality. There will need to be a way to indicate which tests should not be run (or transpiled)

[scaddenp]

Would be improvement if could just a run a version of proj4js tests.

[barthanssens]

So basically a port of https://github.com/OSGeo/PROJ/blob/master/src/apps/gie.cpp , or rather a (pre)processor that converts the GIE test files into JUnit tests ?