added unit test for testing merging of incoming API entities
added unit test for testing merging of incoming API entities

rienafairefr/nYNABapi,rienafairefr/nYNABapi,rienafairefr/pynYNAB,rienafairefr/pynYNAB,rienafairefr/pynYNAB,rienafairefr/pynYNAB,rienafairefr/nYNABapi