Improve test coverage and integration tests
Child issues (updated 2020-12-16):
- #27361
- #28774
- #29358
- #29727
- #30902
- #33166
- #33167
Integration tests with chutney (NL O2.1):
- #33150
- #40008
- #40031
Coverage (NL O2.2):
- #40030
Unit tests (NL O2.2):
- #40032
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