Make interop client fail if the test never finishes

package.json

@@ -60,7 +60,11 @@
       "packages/grpc-native-core/src/*.js",
       "packages/grpc-protobufjs/build/src/*"
     ],
-    "cache": true
+    "cache": true,
+    "all": true,
+    "require": [
+      "ts-node/register"
+    ]
   },
   "scripts": {
     "test": "nyc gulp test",

test/api/interop_sanity_test.js

@@ -68,7 +68,7 @@ describe('Interop tests', function() {
 	  throw new Error(`Server exited with signal ${signal}`);
 	}
       }
-    })
+    });
   });
   after(function() {
     serverProcess.send({});

test/interop/interop_client.js

@@ -616,8 +616,12 @@ if (require.main === module) {
   };
   runTest(argv.server_host + ':' + argv.server_port, argv.server_host_override,
           argv.test_case, argv.use_tls === 'true', argv.use_test_ca === 'true',
-          function () {
+          function (err) {
+            if (err) {
+              throw err;
+            } else {
               console.log('OK:', argv.test_case);
+            }
           }, extra_args);
 }