mirage.config.js

  // vget: like `get` but ensures the response body matches the schema for an endpoint. e.g. `validated get`
  this.vget = (path, callback) => {
    this.get(path, (schema, request) => {
      request.__validationPath__ = `/${path}`;
      return Promise.resolve().then(async () => {
        await ensureSchemaLoaded(request.requestHeaders.Accept);
        return callback.call(this, schema, request);
      });
    });
  };

  const _handledRequest = this.pretender.handledRequest;
  this.pretender.handledRequest = (verb, path, request) => {
    _handledRequest.call(this.pretender, verb, path, request);
    if (request.__validationPath__) {
      try {
        validateRequest(request.__validationPath__, request.requestHeaders.Accept, JSON.parse(request.responseText));
      } catch(e) {
        mocha.throwError(e);
      }
    }
  };
  // dashboard.heroku.com itself (or whatever origin your app is on)
  this.get('/latest-version', () => config.APP_VERSION);