Closes #106: improve test coverage #336

Job	Run time
Get R version	3s
Check / windows-latest (release)	2m 30s
Links / Validate Links	5s
Check / ubuntu-latest (release)	4m 21s
Check / macos-latest (release)	2m 23s
Version Bump	0s
Documentation	0s
Spelling / Spellcheck	5m 7s
Lint / Lint	4m 33s
Code Style / Code Style	4m 40s
Validation	0s
Man Pages / Roxygen	4m 17s
Code Coverage / Test Coverage	4m 23s
Check Templates / Verify	4m 24s
Code Coverage / Generate badge for coverage	-1s
	36m 45s

Provide feedback