$ npm install -g mocha
$ mkdir test
$ $EDITOR test/test.js

var assert = require('assert');
describe('Array', function() {
 describe('#indexOf()', function () {
  it('should return -1 when the value is not present', function () {
   assert.equal(-1, [1,2,3].indexOf(5));
   assert.equal(-1, [1,2,3].indexOf(0));
  });
 });
});

$ mocha

 .

 ✔ 1 test complete (1ms)

describe('User', function() {
 describe('#save()', function() {
  it('should save without error', function(done) {
   var user = new User('Luna');
   user.saveAsync(function(err) {
    if (err) throw err;
    done(); // 只有执行完此函数后，该测试用例算是完成。
   });
  });
 });
});

  /**
   * Describe a "suite" with the given `title`
   * and callback `fn` containing nested suites
   * and/or tests.
   */
  context.describe = context.context = function(title, fn) {
   var suite = Suite.create(suites[0], title);
   suite.file = file;
   suites.unshift(suite);
   fn.call(suite);
   suites.shift();
   return suite;
  };

   /**
   * Describe a specification or test-case
   * with the given `title` and callback `fn`
   * acting as a thunk.
   */

  context.it = context.specify = function(title, fn) {
   var suite = suites[0];
   if (suite.pending) {
    fn = null;
   }
   var test = new Test(title, fn);
   test.file = file;
   suite.addTest(test);
   return test;
  };

describe('hooks', function() {
 before(function() {
  // runs before all tests in this block
  // 在执行所有的测试用例前 函数会被调用一次
 });

 after(function() {
  // runs after all tests in this block
  // 在执行完所有的测试用例后 函数会被调用一次
 });

 beforeEach(function() {
  // runs before each test in this block
   // 在执行每个测试用例前 函数会被调用一次
 });

 afterEach(function() {
  // runs after each test in this block
  // 在执行每个测试用例后 函数会被调用一次
 });

 // test cases
});

 beforeEach(function(done) {
  // 异步函数
  db.clear(function(err) {
   if (err) return done(err);
   db.save([tobi, loki, jane], done);
  });
 });

describe('Array', function() {
 describe('#indexOf()', function() {
  // pending test below 暂时不写回调函数
  it('should return -1 when the value is not present');
 });
});

describe('Array', function() {
 describe.only('#indexOf()', function() {
  // ...
 });
   // 测试集合不会被执行
  describe('#ingored()', function() {
  // ...
 });
});

describe('Array', function() {
 describe('#indexOf()', function() {
  it.only('should return -1 unless present', function() {
   // ...
  });
   // 测试用例不会执行
  it('should return the index when present', function() {
   // ...
  });
 });
});

describe('Array', function() {
  //该测试用例会被ingore掉 
 describe.skip('#indexOf()', function() {
  // ...
 });
  // 该测试会被执行
  describe('#indexOf()', function() {
  // ...
 });
});

describe('Array', function() {
 describe('#indexOf()', function() {
   // 测试用例会被ingore掉
  it.skip('should return -1 unless present', function() {
   // ...
  });
   // 测试用例会被执行
  it('should return the index when present', function() {
   // ...
  });
 });
});

var assert = require('assert');

function add() {
 return Array.prototype.slice.call(arguments).reduce(function(prev, curr) {
  return prev + curr;
 }, 0);
}

describe('add()', function() {
 var tests = [
  {args: [1, 2],    expected: 3},
  {args: [1, 2, 3],  expected: 6},
  {args: [1, 2, 3, 4], expected: 10}
 ];
 // 下面就会生成三个不同的测试用例，相当于写了三个it函数的测试用例。
 tests.forEach(function(test) {
  it('correctly adds ' + test.args.length + ' args', function() {
   var res = add.apply(null, test.args);
   assert.equal(res, test.expected);
  });
 });
});

 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));
  });
 });
});

module.exports = {
 before: function() {
  // ...
 },

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

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);
});

var testCase = require('mocha').describe;
var pre = require('mocha').before;
var assertions = require('mocha').it;
var assert = require('assert');

testCase('Array', function() {
 pre(function() {
  // ...
 });

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