jasmine note-白红宇

jasmine note

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发布时间：2019-06-21

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jasmine

简介

jasmine 是一个测试驱动开发(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有十分简洁的语法

使用

从下载 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的作用是群组相关的测试, 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);    })});

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