Use `go test -i` to install all prerequisite packages (#954)

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

Makefile

@@ -44,7 +44,8 @@ endif
 ifeq ($(TEST_TYPE),coverage)
 	for d in `go list ./... | grep -v vendor`; do \
 		t=$$(date +%s); \
-		go test -v  -tags 'etcd k8s' -coverprofile=cover.out -covermode=atomic $$d || exit 1; \
+		go test -i -tags 'etcd k8s' -coverprofile=cover.out -covermode=atomic $$d || exit 1; \
+		go test -v -tags 'etcd k8s' -coverprofile=cover.out -covermode=atomic $$d || exit 1; \
 		echo "Coverage test $$d took $$(($$(date +%s)-t)) seconds"; \
 		if [ -f cover.out ]; then \
 			cat cover.out >> coverage.txt; \