make node tests pass on macos
diff --git a/tools/run_tests/run_node.sh b/tools/run_tests/run_node.sh
index f93c9c3..40f61d7 100755
--- a/tools/run_tests/run_node.sh
+++ b/tools/run_tests/run_node.sh
@@ -28,8 +28,12 @@
 # (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 $NODE_VERSION
+
 CONFIG=${CONFIG:-opt}
 
 # change to grpc repo root