Add support for setting gcp endpoint for easier testing

lib/cli/cli.js

@@ -1655,6 +1655,10 @@ export async function parseCommandLine() {
       describe: 'Name of the Google Cloud storage bucket',
       group: 'GoogleCloudStorage'
     })
+    .option('gcs.apiEndpoint', {
+      describe: 'The URL to the API endpoint, good for using fake-gcs-server',
+      group: 'GoogleCloudStorage'
+    })
     .option('gcs.public', {
       describe:
         'Make uploaded results to Google Cloud storage publicly readable.',

lib/plugins/gcs/index.js

@@ -15,10 +15,18 @@
 }
 
 async function uploadLatestFiles(dir, gcsOptions, prefix) {
-  const storage = new Storage({
+
+  const config = {
     projectId: gcsOptions.projectId,
     keyFilename: gcsOptions.key
-  });
+  }
+
+  if (gcsOptions.apiEndpoint) {
+    config.apiEndpoint = gcsOptions.apiEndpoint;
+  }
+
+
+  const storage = new Storage(config);
   const bucket = storage.bucket(gcsOptions.bucketname);
 
   const files = await readdir(dir, [ignoreDirectories]);