Detailed introduction to the installation and use of NodeJs testing framework Mocha

$ npm install -g mocha
$ mk
dir
 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);
    });
  });
});
上述默认的接口是BDD, 如果想