fix test script

tonic-interop/test.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+
+
 set -eu
 set -o pipefail
 
@@ -9,10 +11,11 @@ case "$OSTYPE" in
   *)        exit 2 ;;
 esac
 
+ARG="${1:-""}"
 SERVER="tonic-interop/bin/server_${OS}_amd64"
 
 # run the test server
-./"${SERVER}" $1 &
+./"${SERVER}" $ARG &
 SERVER_PID=$!
 echo ":; started grpc-go test server."
 
@@ -23,4 +26,4 @@ trap 'echo ":; killing test server"; kill ${SERVER_PID};' EXIT
  cargo run -p tonic-interop --bin client -- \
  --test_case=empty_unary,large_unary,client_streaming,server_streaming,ping_pong,\
 empty_stream,status_code_and_message,special_status_message,unimplemented_method,\
-unimplemented_service,custom_metadata $1
+unimplemented_service,custom_metadata $ARG