restored some unit tests for serializer
restored some unit tests for serializer


Former-commit-id: 5eb7a2f6200905cb72bf919a1c0dc06365c08bb1 [formerly 5eb7a2f6200905cb72bf919a1c0dc06365c08bb1 [formerly 3e01fff405e18e1d227dee47a9df3c4d45ead2ae]]
Former-commit-id: df30da8fb6f15b0c97bf6ae2718aefb4d16615c5
Former-commit-id: bcf268143e14c3d2599f24d1bbf463122f770cb8
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine