make node tests pass on macos
diff --git a/tools/run_tests/pre_build_node.sh b/tools/run_tests/pre_build_node.sh
index 28ce354..40213b8 100755
--- a/tools/run_tests/pre_build_node.sh
+++ b/tools/run_tests/pre_build_node.sh
@@ -29,8 +29,12 @@
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+NODE_VERSION=$1
+source ~/.nvm/nvm.sh
set -ex
+nvm use $NODE_VERSION
+
export GRPC_CONFIG=${CONFIG:-opt}
# Expire cache after 1 week