Chai:如何使用'should'语法测试undefined

Question

在本教程中使用chai测试angularjs应用程序时,我想使用"should"样式为未定义的值添加测试.这失败了:

it ('cannot play outside the board', function() {
  scope.play(10).should.be.undefined;
});

错误"TypeError:无法读取属性'应该'未定义",但测试通过了"expect"样式:

it ('cannot play outside the board', function() {
  chai.expect(scope.play(10)).to.be.undefined;
});

如何让它与"应该"一起工作？

Answer 1

这是should语法的缺点之一.它的工作原理是将should属性添加到所有对象,但如果返回值或变量值未定义,则没有对象来保存该属性.

该文档提供了一些解决方法,例如:

var should = require('chai').should();
db.get(1234, function (err, doc) {
  should.not.exist(err);
  should.exist(doc);
  doc.should.be.an('object');
});

Answer 2

should.equal(testedValue, undefined);

正如柴文献中所述

Answer 3

测试未定义

var should = require('should');
...
should(scope.play(10)).be.undefined;

测试null

var should = require('should');
...
should(scope.play(10)).be.null;

测试假,即在条件下视为假

var should = require('should');
...
should(scope.play(10)).not.be.ok;

Answer 4

(typeof scope.play(10)).should.equal('undefined');

Answer 5

我努力为未定义的测试编写should语句.以下不起作用.

target.should.be.undefined();

我找到了以下解决方案.

(target === undefined).should.be.true()

如果还可以将其写为类型检查

(typeof target).should.be.equal('undefined');

不确定上述是否正确,但确实有效.

根据Github中鬼的帖子

Answer 6

试试这个:

it ('cannot play outside the board', function() {
   expect(scope.play(10)).to.be.undefined; // undefined
   expect(scope.play(10)).to.not.be.undefined; // or not
});