chai-contained
使用範例
var chai = require('chai')
, expect = chai.expect
, chaiContained = require('chai-contained');
expect('foo').to.be.containedIn(['foo', 'bar']); // will pass
expect('foo').to.be.containedIn(['noFoo', 'baz']); // will fail
稍後會失敗並顯示訊息:AssertionError: expected 'foo' to be one of the [ 'noFoo', 'baz' ]