Correctly include ext in coverage

Author: MilesCranmer

coverage.jl

@@ -1,14 +1,15 @@
 using Coverage
 # process '*.cov' files
 coverage = process_folder() # defaults to src/; alternatively, supply the folder name as argument
+coverage = cat(coverage, process_folder("ext"); dims=1) # add coverage from ext/
 
 LCOV.writefile("lcov.info", coverage)
 
 # process '*.info' files
 coverage = merge_coverage_counts(
     coverage,
     filter!(
-        let prefixes = (joinpath(pwd(), "src", ""),)
+        let prefixes = (joinpath(pwd(), "src", ""), joinpath(pwd(), "ext", ""))
             c -> any(p -> startswith(c.filename, p), prefixes)
         end,
         LCOV.readfolder("test"),