chore: block auth during public system tests (#438)

package.json

@@ -112,6 +112,7 @@
     "@types/mime": "^2.0.0",
     "@types/mime-types": "^2.1.0",
     "@types/mocha": "^5.2.3",
+    "@types/nock": "^9.3.0",
     "@types/once": "^1.4.0",
     "@types/proxyquire": "^1.3.28",
     "@types/pumpify": "^1.4.1",
@@ -129,6 +130,7 @@
     "intelli-espower-loader": "^1.0.1",
     "jsdoc": "^3.5.4",
     "mocha": "^5.0.0",
+    "nock": "^10.0.1",
     "node-fetch": "^2.2.0",
     "normalize-newline": "^3.0.0",
     "nyc": "^13.0.0",

system-test/storage.ts

@@ -31,6 +31,13 @@ import * as uuid from 'uuid';
 import {util, ApiError, InstanceResponseCallback, BodyResponseCallback} from '@google-cloud/common';
 import {Storage, Bucket} from '../src';
 import {DeleteBucketCallback} from '../src/bucket';
+import * as nock from 'nock';
+
+// block all attempts to chat with the metadata server (kokoro runs on GCE)
+nock('http://metadata.google.internal')
+    .get(url => true)
+    .replyWithError({code: 'ENOTFOUND'})
+    .persist();
 
 // tslint:disable-next-line:variable-name
 const PubSub = require('@google-cloud/pubsub');
@@ -113,7 +120,6 @@ describe('storage', () => {
 
         const {Storage} = require('../src');
         storageWithoutAuth = new Storage();
-
         done();
       });
     });