I've found that the commas_linter does not recognize lints when the line to be linted is preceded by a blank line or a commented line. Below is a minimal working example:

file: Test.r

#random comment

a <- c(4,5)
b = 7

Then, I run the following:

lintr::lint("./Test.r", linters = list(spacesAfterCommas = commas_linter, 
                                       useArrowForAssignments = assignment_linter))

The only error I get is the following:

./Test.r:4:3: style: Use <-, not =, for assignment.
b = 7
  ^

Why is the commas_linter not catching my error? If I remove the blank line, commas_linter catches the lint.