[giac] adding more test-cases

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30160 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
corrected JUnit test errors

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30161 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e