Some DM files are critical to VE operation and should be easy to get to 100% code coverage:
https://doc.wikimedia.org/cover/visualeditor/src/dm/index.html
- ve.dm.Converter (95%)
- ve.dm.ElementLinearData (98%)
- ve.dm.Transaction (80%)
- ve.dm.TransactionBuilder (97%)
- ve.dm.TransactionProcessor (85%)
- ve.dm.ModelRegistry (92%)