Increase test coverage

[stitam]

webchem's test coverage has fallen lately. The rOpenSci policy is 75% so let's bring it up to at least 75%.

https://devguide.ropensci.org/building.html#testing

[Aariq]

What is the coverage when tests are run locally (i.e. ChemSpider is not skipped)? Might not be an issue, or might be a (somewhat) easy fix by adding a ChemSpider API token as a GitHub secret, then un-skipping those tests on CI.

[stitam]

I might ask for some help there, if I run covr::package_coverage() from the dev directory, I get 0% for everything, I am clearly missing something. On the other hand, ChemSpider is skipped because of the missing token and Flavornet seems to be down.

[Aariq]

I can give it a try later this week.

[Aariq]

Local test coverage (with chemspider) is ~ 80%. But utils.R has lowest coverage, so boosting is probably a better idea than having chemspider tests run on CI.