单元测试依赖项注入

Question

我想模拟类中的依赖关系，但我找不到正确的方法来实现这一点。使用sinon进行单元测试。例如：

const { classB } = require("./classes/classB");
const { classC } = require("./classes/classC");
const sinon = require("sinon");
class classA {
constructor() {
this.classB = new classB();
this.classC = new classC();
}

doSomething() {
const data = this.classB.getInfo();
const processed = processInfo(data);
this.classC.processedData(processed);

}

processInfo(data) {
// doesSomeProcessing
}
}
module.exports = {
classA
};
describe("classA", () => {
describe("when instantiated", () => {
it("calls classB's getInfo once, classC's processedData data once.", () => {
sinon.stub(classB);
let clsA = new classA();
sinon.assert.calledOnce(classB.getInfo);
sinon.assert.calledOnce(classC.processedData);
// Also can we do something like this?
// when classB.getinfo.then(provideMockData) 
// so that we can mock the calls being made to avoid actual calls?
});
});
});

我试着对此进行研究，但找不到可行的解决方案。任何见解都会非常有帮助！提前表示感谢，并对由此造成的任何麻烦表示歉意！

Answer 1

您应该使用链接接缝来截断依赖关系。

例如

classA.js:

const { ClassB } = require('./classB');
const { ClassC } = require('./classC');
class ClassA {
constructor() {
this.classB = new ClassB();
this.classC = new ClassC();
}
doSomething() {
const data = this.classB.getInfo();
this.classC.processedData(data);
}
}
module.exports = { ClassA };

classB.js:

class ClassB {
getInfo() {
return 'real data';
}
}
module.exports = { ClassB };

classC.js:

class ClassC {
processedData(data) {
return 'real process data';
}
}
module.exports = { ClassC };

classA.test.js:

const sinon = require('sinon');
const proxyquire = require('proxyquire');
describe('66751571', () => {
it('should pass', () => {
const classBInstanceStub = {
getInfo: sinon.stub().returns('teresa teng'),
};
const classCInstanceStub = {
processedData: sinon.stub(),
};
const ClassBStub = sinon.stub().returns(classBInstanceStub);
const ClassCStub = sinon.stub().returns(classCInstanceStub);
const { ClassA } = proxyquire('./classA', {
'./classB': { ClassB: ClassBStub },
'./classC': { ClassC: ClassCStub },
});
const clsA = new ClassA();
clsA.doSomething();
sinon.assert.calledOnce(classBInstanceStub.getInfo);
sinon.assert.calledWithExactly(classCInstanceStub.processedData, 'teresa teng');
});
});

单元测试结果：

66751571
✓ should pass (2326ms)

1 passing (2s)
-----------|---------|----------|---------|---------|-------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
-----------|---------|----------|---------|---------|-------------------
All files  |   81.82 |      100 |      50 |   81.82 |                   
classA.js |     100 |      100 |     100 |     100 |                   
classB.js |      50 |      100 |       0 |      50 | 3                 
classC.js |      50 |      100 |       0 |      50 | 3                 
-----------|---------|----------|---------|---------|-------------------