chore: use composite builds for tests (#8522)

.mocharc.cjs

@@ -0,0 +1,27 @@
+/**
+ * Copyright 2020 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+module.exports = {
+  reporter: 'dot',
+  logLevel: 'debug',
+  require: ['./test/build/mocha-utils.js', 'source-map-support/register'],
+  spec: 'test/build/*.spec.js',
+  exit: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  parallel: !!process.env.PARALLEL,
+  timeout: 25 * 1000,
+  reporter: process.env.CI ? 'spec' : 'dot',
+};