npm install mocha -g

const assert = require('assert');

// 测试Array类型的方法
suite('Array', function() {
 // 测试 indexOf方法
 suite('#indexOf()', function() {
  // 测试用例
  test('should return -1 when not present', function() {
   assert.equal(-1, [1, 2, 3].indexOf(4));
  });
 });
});

const should = require('should');

const user = {
 name: 'tj'
 , pets: ['tobi', 'loki', 'jane', 'bandit']
};

user.should.have.property('name', 'tj');
user.should.have.property('pets').with.lengthOf(4);

// If the object was created with Object.create(null)
// then it doesn't inherit `Object.prototype`, so it will not have `.should` getter
// so you can do:
should(user).have.property('name', 'tj');

// also you can test in that way for null's
should(null).not.be.ok();

someAsyncTask(foo, function(err, result){
 should.not.exist(err);
 should.exist(result);
 result.bar.should.equal(foo);
});

user.should.be.an.instanceOf(Object).and.have.property('name', 'tj');
user.pets.should.be.instanceof(Array).and.have.lengthOf(4);

// bool类型判断
(true).should.be.true();
false.should.not.be.true();

// 数组是否包含
[ 1, 2, 3].should.containDeep([2, 1]);
[ 1, 2, [ 1, 2, 3 ]].should.containDeep([ 1, [ 3, 1 ]]);

// 数字比较
(10).should.not.be.NaN();
NaN.should.be.NaN();
(0).should.be.belowOrEqual(10);
(0).should.be.belowOrEqual(0);
(10).should.be.aboveOrEqual(0);
(10).should.be.aboveOrEqual(10);

// Promise状态判断
// don't forget to handle async nature
(new Promise(function(resolve, reject) { resolve(10); })).should.be.fulfilled();

// test example with mocha it is possible to return promise
it('is async', () => {
 return new Promise(resolve => resolve(10))
  .should.be.fulfilled();
});

// 对象的属性判断
({ a: 10 }).should.have.property('a');
({ a: 10, b: 20 }).should.have.properties({ b: 20 });
[1, 2].should.have.length(2);
({}).should.be.empty();

// 类型检查
[1, 2, 3].should.is.Array();
({}).should.is.Object();

describe('Array', function() {
 before(function() {
  // ...
 });

 describe('#indexOf()', function() {
  context('when not present', function() {
   it('should not throw an error', function() {
    (function() {
     [1, 2, 3].indexOf(4);
    }.should.not.throw());
   });
   it('should return -1', function() {
    [1, 2, 3].indexOf(4).should.equal(-1);
   });
  });
  context('when present', function() {
   it('should return the index where the element first appears in the array', function() {
    [1, 2, 3].indexOf(3).should.equal(2);
   });
  });
 });
});

suite('Array', function() {
 setup(function() {
  // ...
 });

 suite('#indexOf()', function() {
  test('should return -1 when not present', function() {
   assert.equal(-1, [1, 2, 3].indexOf(4));
  });
 });
});

function ok(expr, msg) {
 if (!expr) throw new Error(msg);
}

suite('Array');

test('#length', function() {
 var arr = [1, 2, 3];
 ok(arr.length == 3);
});

test('#indexOf()', function() {
 var arr = [1, 2, 3];
 ok(arr.indexOf(1) == 0);
 ok(arr.indexOf(2) == 1);
 ok(arr.indexOf(3) == 2);
});

suite('String');

test('#length', function() {
 ok('foo'.length == 3);
});