This happens specifically for 3D tests when run on virtual machine or on a system which does not have a graphics card.

Tests under these classes list as "passed" although stderr states otherwise.
test.robot.test3d.TriangleMeshPNTValidationTest
test.robot.test3d.TriangleMeshValidationTest

There are many more which fall under this category. The reason could be that after checking the conditional feature , there is a return which conveniently marks the testcase as passed. Changes to be made to instead ignore the test on missing feature support.