CI coverage: add missing Lua files to the report

Luacov does not know about files which were not loaded at all.
Script luacov_gen_empty.sh generates empty luacov stats for all files
which forces luacov to show all files.

Makefile

@@ -14,12 +14,15 @@ coverage-c:
 	@echo "# C coverage in $(COVERAGE_STAGE).c.info"
 	@$(LCOV) --no-external --capture -d lib -d daemon -d modules -o $(COVERAGE_STAGE).c.info > /dev/null
 coverage-lua: $(shell find -type f -name 'luacov.stats.out')
-	# map install paths to source paths
+	@# map install paths to source paths
 	@$(MAKE) PREFIX=$(PREFIX) install --dry-run --always-make | scripts/map_install_src.lua --sed > .luacov_path_map
 	@find -type f -name 'luacov.stats.out' | xargs sed -i -f .luacov_path_map
 	@rm .luacov_path_map
+	@# add missing Lua files
+	@$(MAKE) PREFIX=$(PREFIX) install --dry-run --always-make | scripts/map_install_src.lua | cut -f 2 | grep '\.lua$$' | scripts/luacov_gen_empty.sh > luacov.empty_stats.out
 	@echo "# Lua coverage in $(COVERAGE_STAGE).lua.info"
-	@scripts/luacov_to_info.lua $^ > $(COVERAGE_STAGE).lua.info
+	@scripts/luacov_to_info.lua luacov.empty_stats.out $^ > $(COVERAGE_STAGE).lua.info
+	@rm luacov.empty_stats.out
 coverage:
 	@$(LCOV) $(addprefix --add-tracefile ,$(wildcard $(COVERAGE_STAGE)*.info)) --output-file coverage.info
 	@$(GENHTML) --no-function-coverage --no-branch-coverage -q -o coverage -p $(realpath $(CURDIR)) -t "Knot DNS Resolver $(VERSION)-$(PLATFORM) coverage report" --legend coverage.info

scripts/luacov_gen_empty.sh

+#!/bin/bash
+# Generate stats file in luacov format indicating that files named on stdin
+# were not processed.
+#
+# Normally luacov does not know about files which were not loaded so
+# without this manual addition the files are missing in coverage report.
+
+# Usage:
+# $ luacov_gen_empty.sh < list_of_lua_files > luacov.empty_stats.out
+
+set -o errexit -o nounset
+IFS=$'\n'
+
+while read FILENAME
+do
+	echo -e "0:${FILENAME}\n "
+done