Provide locations of zero coverage — zero

When examining the test coverage of a package, it is useful to know if there are any locations where there is 0 test coverage.

zero_coverage(x, ...)

Arguments

x	a coverage object returned `package_coverage()`
...	additional arguments passed to `tally_coverage()`

A data.frame with coverage data where the coverage is 0.

if used within RStudio this function outputs the results using the Marker API.