With a quick skim through the names of the test files, I didn't spot and group / off_by tests.
GIVEN one `<region>`s with the same `off_by=` value
AND a second `<region>` with a `group=` value that matches the first region's `off_by=` value
AND the second `<region>` region is triggered by a different note number
AND the first region has been triggered and is still playing
WHEN the second region is triggered
THEN the first region should stop, using the `off_mode=` value
GIVEN one `<region>`s with the same `off_by=` value
AND a second `<region>` with a `group=` value that matches the first region's `off_by=` value
AND the second `<region>` region is triggered by the same note number
AND the first region has been triggered and is still playing
WHEN the second region is triggered
THEN the first region should not be affected
GIVEN one `<region>`s with the same `off_by=` value
AND a second `<region>` with a `group=` value that matches the first region's `off_by=` value
AND the second `<region>` region is triggered by a different note number
AND the first region has been triggered and is still playing
WHEN the second region is triggered
THEN the first region should stop, using the `off_mode=` value
GIVEN one `<region>`s with the same `off_by=` value
AND a second `<region>` with a `group=` value that matches the first region's `off_by=` value
AND the second `<region>` region is triggered by the same note number
AND the first region has been triggered and is still playing
WHEN the second region is triggered
THEN the first region should stop, using the `off_mode=` value