Detect Unmatched nocov Markers

Check whether the nocov start and nocov end comment markers in R source files are consistent.

Every marker is first located on its own line and column, and the markers are then checked against the rules below.

Detection is purely textual: every line is scanned for a marker comment, so a marker that hides inside a string literal or inside a documentation comment (a roxygen #' line) is reported as well. This is intentional – such a marker has no effect on coverage, which usually means it is a leftover that should be removed by hand.

Usage

package_unmatched_nocov_marker(path = NULL, dirs = "R", verbose = TRUE)

detect_unmatched_nocov_marker(path = NULL, verbose = TRUE, ...)

Arguments

path

For detect_unmatched_nocov_marker(): path to an R file. If NULL and RStudio is available, the active document path is used.

For package_unmatched_nocov_marker(): path to the root directory of an R package. Defaults to the current directory.

dirs

Character vector of package-relative directories scanned by package_unmatched_nocov_marker(). Defaults to "R".

verbose

Whether to emit detection results to the console.

...

Unused.

Value

Invisibly returns TRUE when the markers of the file follow the rules above, and FALSE otherwise. Each problem is printed with its line and column, the source line and a caret marker pointing at the offending comment, so that the fix is left to the user.

Marker rules

A file may contain at most one nocov start and at most one nocov end marker, so the two counts must be equal: either both are present or neither is.

Second and later nocov start

Reported as a problem: only the first start is meaningful, so every further start is echoed with its line and column.

Second and later nocov end

Reported as a problem for the same reason.

nocov start without nocov end

Reported as a problem: covr::package_coverage() aborts with a "range start but only range ends" error when a start is never closed, so a lone start must be fixed.

nocov end without nocov start

Reported as a problem: the block it closes does not exist.

nocov end before nocov start

Reported as a problem: the end must come after the start. Markers are compared by line first and then by column, so an end placed later on the same line is accepted.

Single file vs package scope

detect_unmatched_nocov_marker()

Operates on one R file. When path is NULL and RStudio is available, the currently active document path is used.

package_unmatched_nocov_marker()

Scans the .R files under the configured package-relative directories, by default R/, and reports every problem together with its file name and line number.

Examples

# \donttest{
file <- tempfile(fileext = ".R")
writeLines(c("f <- function() 1", paste0("# nocov", " end")), file)
detect_unmatched_nocov_marker(file)
#> ✖ `nocov end` at line 2, column 1 has no matching `nocov start`.
#> # nocov end
#> ^^^^^^^^^^^
#> ✖ Found 1 mismatched `nocov` marker on line 2.
# }