I figured out that two things were wrong: 1. the points for the preciseGeometry should be converted to the coordinates system of the preciseGeometry. 2. The comparePlanarFigure method was testing if the class names are equal and would return false if not. If the NAMES are equal, the other conditions were required to be equal for a successful test. But a PlanarCross with a preciseGeometry is obviously not equal to a PlanarCross with a planeGeometry.

In conclusion, the test was wrong and never anything in the IO at all ... I added various planarFigures to the test which also use the preciseGeometry to have a better test coverage.