test: Add tools to generate test coverage information

This patch adds some tooling and scripts to generate test coverage
information.

Unfortunately, this involves some hacks as Go does not have support for
generating coverage-enabled binaries, or merging coverage reports; but
overall it's not very intrusive.

test/util/lib.sh

@@ -29,6 +29,11 @@ function generate_cert() {
 }
 
 function chasquid() {
+	if [ "${COVER_DIR}" != "" ]; then
+		chasquid_cover "$@"
+		return
+	fi
+
 	# HOSTALIASES: so we "fake" hostnames.
 	# PATH: so chasquid can call test-mda without path issues.
 	# MDA_DIR: so our test-mda knows where to deliver emails.
@@ -38,6 +43,24 @@ function chasquid() {
 		go run ${RACE} ${TBASE}/../../chasquid.go "$@"
 }
 
+function chasquid_cover() {
+	# Build the coverage-enabled binary.
+	# See coverage_test.go for more details.
+	( cd ${TBASE}/../../;
+	  go test -covermode=count -coverpkg=./... -c -tags coveragebin )
+
+	# Run the coverage-enabled binary, named "chasquid.test" for hacky
+	# reasons.  See the chasquid function above for details on the
+	# environment variables.
+	HOSTALIASES=${TBASE}/hosts \
+	PATH=${UTILDIR}:${PATH} \
+	MDA_DIR=${TBASE}/.mail \
+		${TBASE}/../../chasquid.test \
+			-test.run "^TestRunMain$" \
+			-test.coverprofile="$COVER_DIR/test-`date +%s.%N`.out" \
+			"$@"
+}
+
 function add_user() {
 	CONFDIR="${CONFDIR:-config}"
 	DOMAIN=$(echo $1 | cut -d @ -f 2)