jasmine官方api参考

最新推荐文章于 2025-08-19 15:52:54 发布

转载最新推荐文章于 2025-08-19 15:52:54 发布 · 82 阅读

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#测试 #驱动开发

Jasmine 是一个用于 JavaScript 的行为驱动开发(BDD)测试框架，支持多种匹配器及测试组织方式。本文介绍 Jasmine 的基本概念、核心语法、常用 API 和测试组织技巧。

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jasmine

简介

jasmine 是一个行为驱动开发(TDD)测试框架，一个js测试框架，它不依赖于浏览器、dom或其他js框架

jasmine有十分简介的语法

使用

从这里下载 stantd-alone安装包，并解压，双击打开里面的 specRunner.html，即可看到测试示例，我们只要将自己的js源文件和测试文件分别放到 src 和 spec 文件夹中。

specRunner.html 到底是长什么样子的呢？ f12 我们发现先后加载了 jasmine.css， jasmine.js ，jasmine-html.js， boot.jsjasmine框架相关文件和我们的 js源文件 jasmine测试文件

语法

分组 describe()

describe的作用的群组相关的测试, describe是可以嵌套的从外到内 walkdown describe层级的 beforeEach, 由内到外walkup describe层级的 afterEach

describe('a suite', function(){ //这是一个测试分组
    it('with an expactation',function(){
        expect(true).toBe(true);
    });
});

测试it()

describe 和 it 都是函数，所以它们可以包含任何js代码，在 describe 中声明的变量和方法，能在 it中被访问。

it 代表的是具体的测试，当其中所有的断言都为true时，则该测试通过；否则测试失败

describe('a suit is just a function', function(){
    var a = 10;
    it('and here is a test', function(){
        var a = true;
        expect(a).toBe(true);
    });
});

期望expect()

desribe('the "toBe" matcher compares with "===" ', function(){
    it('positive expect', function(){
        expect(true).toBe(true);
    });

    it('negative expect', function(){
        expect(false).not.toBe(true);
    });
});

匹配 to*() ####
每个匹配方法在期望值和实际值之间执行逻辑比较，它负责告诉jasmine断言的真假，从而决定测试的成功或失败。

肯定断言 expect(true).toBe(true);
否定断言 expect(false).not.toBe(true);

jasmine有很丰富的匹配方法，而且可以自定义匹配方法。内置的匹配方法有：

toBe()
toEqual()
toMatch()
toBeUndefined()
toBeNull()
toBeTruthy()
toContain()
toBeLessThan()
toBeCloseTo()

toThrowError()

  describe("included matchers", function(){
      it('"toBe" matcher compares width === ', function(){
          var a = 12;
          var b = a;
          expect(a).toBe(b);
          expect(a).not.toBe(null);
      });

      describe('"toEqual" matcher', function(){
          it('work for simple literals and variable', function(){
              var a = 12;
              expect(a).toEqual(12);
          });

          it('should work for objects', function(){
              var foo = {
                  a: 12,
                  b: 23
              };
              var bar = {
                  a: 12,
                  b: 23
              };

              expect(foo).toEqual(bar); //true?
          });
      });

      it('"toMatch" matcher is for regular expression', function(){
          var message = "foo bar baz";
          expect(message).toMatch(/bar/);
          expect(message).toMatch("bar");
          expect(message).not.toMatch(/quue/);
      });

      it('"toBeUndefined" matcher compares against "undefined"', function(){
          var a = {
              foo: "foo"
          };

          expect(a.foo).not.toBeUndefined();
          expect(a.bar).toBeUndefined();
      });

      it(' "toBeNull" matcher compares against "null"', function(){
          var a = null;
          var foo = 'foo';

          expect(null).toBeNull();
          expect(a).toBeNull();
          expect(foo).not.toBeNull();
      });

      it('"toBeTruthy" matcher is for boolean casting testing' , function(){
          var a, foo = 'foo';
          expect(foo).toBeTruthy();
          expect(a).not.toBeTruthy();
      });

      it('"toContain" matcher is for finding an item in an array', function(){
          var a = ['foo', 'bar', 'baz'];
          expect(a).toContain('bar');
          expect(a).not.toContain('quu');
      });

      it('"toBeLessThan" matcher is for math comparisons', function(){
          var n = 2.23, e = 1.33;
          expect(e).toBeLessThan(n);
          expect(n).not.toBeLessThan(e);
      });

      it('"toBeCloseTo" matcher is for precision match comparison', function(){
          var n = 1.99, e = 2.35;
          expect(e).not.toBeCloseTo(n, 2);
          expect(e).toBeCloseTo(n, 0);
      });


      it('"toThrowError" matcher is for testing a specific thrown exception', function(){
          var foo = function(){
              throw new TypeError('foo bar baz');
          };
          expect(foo).toThrowError('foo bar baz');
          expect(foo).toThrowError(/bar/);
          expect(foo).toThrowError(TypeError);
          expect(foo).toThrowError(TypeError, 'foo bar baz');
      });
  });

设置和清理 beforeEach(), afterEach()

beforeEach() 在它所属的 describe 块中的每条测试执行前，先执行的js代码，作用就是设置和初始化一些东西。
afterEach() 和 beforeEach 相反，在 describe 块的每条测试执行后执行，做一些清理的工作。

describe('tests with "setup" and "tear-down"', function(){
    var foo;
    beforeEach(function(){
        foo = 0;
        foo += 1; //每次测试前都初始化 foo == 1
    });

    afterEach(function(){
        foo = 0; //每次测试完都重置 foo = 0;
    });

    it('it is just a function , so can contain any code', function(){
        expect(foo).toEqual(1);

    });

    it('can have more than one expectation', function(){
        expect(foo).toEqual(1);
        expect(true).toEqual(true);
    });
});

this对象

另一种在 beforeEach afterEach it 之间共享变量的方法： this对象, 每次执行完1条测试之后，this 都会被重置为空对象

describe('a suite', function(){
    beforeEach(function(){
        this.foo = 0;
    });

    it('can use "this" to share initial data', function(){
        expect(this.foo).toEqual(0);
        this.bar = "test pollution?";
    });

    it('prevents test pollution by having an empty "this" created for next test', function(){
        expect(this.foo).toEqual(0);
        expect(this.bar).toBe(undefined);
    });
});

describe嵌套 beforeEach串行

describe('a suite', function(){
    var foo;
    beforeEach(function(){
        foo = 0;
        foo += 1;
    });
    afterEach(function(){
        foo = 0;
    });

    it('a spec', function(){
        expect(foo).toEqual(1);
    });
    it('a spec too', function(){
        expect(foo).toEqual(1);
        expect(true).toEqual(true);
    });

    describe('nested inside describe', function(){
        var bar; 

        beforeEach(function(){
            bar = 1;
        });

        // exec outer's describe beforeEach > this describe's beforeEach
        it('可以访问外部describe的beforeEach的变量', function(){
            expect(foo).toEqual(bar);
        });
    });
});

禁用describe或it

xdescribe(), xit() 和 pending()

xdescribe('a suite',function(){
    //will not execute
});

describe('a suite too', function(){
    xit('this test be canceled', function(){
        expect(true).toBe(false);
    });

    it('can be desclared with "it" but without a function');

    if('can be declared by calling "pending()" in spec body', function(){
        expect(true).toBe(false);
        pending(); //禁用该测试
    });
});

函数调用监听 spy

spyOn() , toHaveBeenCalled() , toHaveBeenCalledWith()

describe('a spy', function(){
    var foo, bar = null;
    beforeEach(function(){
        foo = {
            setBar = function(value){
                bar = value;
            };
        };

        spyOn(foo, 'setBar');

        foo.setBar(123);
        foo.setBar(456, 'another param');
    });

    it('tracks that the spy was called', function(){
        expect(foo.setBar).toHaveBeenCalled();
    });

    it('tracks all the arguments of its calls', function(){
        expect(foo.setBar).toHaveBeenCalledWith(123);
        expect(foo.setBar).toHaveBeenCalledWith(456, 'another param');
    });

    it('stops all execution on a function', function(){
        expect(bar).toBeNull(); //setBar函数的执行 被spy监听器暂停了。
    });
});

describe('a spy, when configured to call through', function(){
    var foo , bar, fetchedBar;

    beforeEach(function(){
        foo = {
            setBar: function(value){
                bar = value;
            },
            getBar: function(){
                return bar;
            }
        };

        spyOn(foo, 'getBar').and.callThrough();

        foo.setBar(123);
        fetchedBar = foo.getBar();
    });

    it('tracks that the spy was called', function(){
        expect(foo.getBar).toHaveBeenCalled();
    });
    
    it('should not effect other function', function(){
        expect(bar).toEqual(123);
    });

    it('when called returns the requested value' , function(){
        expect(fetchedBar).toEqual(123);
    })
});