Closes #302 Adding Snapshot testing guidance to unit testing vignette #634

Job	Run time
Render README	0s
Validation	0s
Documentation	0s
Spelling / Get R version	1s
Code Style / Get R version	1s
Check / (4.1)	2m 0s
Check / (4.2)	2m 32s
Check / (4.3)	2m 0s
Lint / Get R version	2s
Code Coverage / Get R version	1s
Links / Validate Links	5s
Man Pages / Get R version	1s
Spelling / Spellcheck	2m 17s
Man Pages / Roxygen	1m 44s
Code Style / Code Style	1m 42s
Code Coverage / Test Coverage	2m 48s
Lint / Lint	2m 44s
Code Coverage / Generate badge for coverage	7s
	18m 5s

Provide feedback