something is working

node_modules/mongoose/lib/helpers/printJestWarning.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const utils = require('../utils');
+
+if (typeof jest !== 'undefined' && typeof window !== 'undefined') {
+  utils.warn('Mongoose: looks like you\'re trying to test a Mongoose app ' +
+    'with Jest\'s default jsdom test environment. Please make sure you read ' +
+    'Mongoose\'s docs on configuring Jest to test Node.js apps: ' +
+    'https://mongoosejs.com/docs/jest.html');
+}
+
+if (typeof jest !== 'undefined' && process.nextTick.toString().indexOf('nextTick') === -1) {
+  utils.warn('Mongoose: looks like you\'re trying to test a Mongoose app ' +
+    'with Jest\'s mock timers enabled. Please make sure you read ' +
+    'Mongoose\'s docs on configuring Jest to test Node.js apps: ' +
+    'https://mongoosejs.com/docs/jest.html');
+}