如何模拟sinon中的文件I/O ?

Question

我有一个从目录解压缩文件的函数。

index.js

const unZip = async (zipFilePath, destDir) => {
await util.promisify(fs.mkdir)(destDir);
return new Promise((resolve, reject) => {
fs.createReadStream(zipFilePath)
.pipe(unzipper.Extract({ path: destDir }))
.on("close", () => resolve(destDir))
.on("error", (err) => {
console.log("Error inside unzip", err);
reject(err);
});
});
};

但对于单元测试，我使用sinon和ava，在那里我无法通过测试用例下面是代码

index.test.js

ava.beforeEach(() => {
// mockFs({
//   'fakeDir/fakeFile': mockFs.load('test/helpers/file/testFile.txt'),
//   fakeFileContent: 'content here',
// });
sinon.stub(mockFs, 'createReadStream').returns({
pipe: sinon.stub().returns({
on: sinon.stub().returns({
on: sinon.stub().returns(),
}),
}),
});
});
ava.serial('unZip test', async (t) => {
const unzip = proxyquire('../../../src/helpers/file/unZip', {
fs: mockFs,
util: {},
unzipper: { Extract: () => Buffer.from([8, 6, 7, 5, 3, 0, 9]) },
});
const result = await unzip('fakeFileContent', 'fakeFileContent');
t.is(result, true);
});

它给出了这样的错误

unZip test
Rejected promise returned by test. Reason:
Error {
code: 'EEXIST',
errno: -17,
path: 'fakeFileContent',
syscall: 'mkdir',
message: 'EEXIST: file already exists, mkdir 'fakeFileContent'',
}

Answer 1

试试这个

index.test.js

const mockFs = {
createReadStream: function () {
return this;
},
mkdir: function (p, cb) {
cb(null, this);
},
pipe: function () {
return this;
},
on: function (param, cb) {
if (param === 'close') {
return cb();
}
if (param === 'error') {
return this;
}
},
};
ava.serial('unZip success', async (t) => {
const unzip = proxyquire('../../../src/helpers/file/unZip', {
fs: mockFs,
util: {},
unzipper: { Extract: () => Buffer.from([8, 6, 7, 5, 3, 0, 9]) },
});
const mockZipFilePath = '../file/testFile.txt';
const destinationFilePath = '../file';
const result = await unzip(mockZipFilePath, destinationFilePath);
t.is(result, destinationFilePath);
});

Answer 2

您不需要使用proxyquire包，使用sinon.stub(obj, 'method')来stub对象的方法。您可以存根fs.mkdir,unzipper.Extract和fs.createReadStream方法。

您使用util.promisify将fs.mkdir转换为承诺形式并调用它，但底层仍然是正在调用的回调，因此您需要使用.callsFake()方法来模拟fs.mkdir的实现，并在测试用例中手动调用回调。

下面的例子使用mocha作为测试框架，但ava也应该可以。

index.js:

const fs = require('fs');
const util = require('util');
const unzipper = require('unzipper');
const unZip = async (zipFilePath, destDir) => {
await util.promisify(fs.mkdir)(destDir);
return new Promise((resolve, reject) => {
fs.createReadStream(zipFilePath)
.pipe(unzipper.Extract({ path: destDir }))
.on('close', () => resolve(destDir))
.on('error', (err) => {
console.log('Error inside unzip', err);
reject(err);
});
});
};
module.exports = unZip;

index.test.js:

const unZip = require('./');
const fs = require('fs');
const sinon = require('sinon');
const unzipper = require('unzipper');
describe('69616649', () => {
afterEach(() => {
sinon.restore();
});
it('should pass', async () => {
sinon.stub(fs, 'mkdir').callsFake((path, callback) => {
callback();
});
const rs = {
pipe: sinon.stub().returnsThis(),
on: sinon.stub().callsFake(function (event, callback) {
if (event === 'close') {
callback();
}
}),
};
sinon.stub(fs, 'createReadStream').returns(rs);
sinon.stub(unzipper, 'Extract');
const actual = await unZip('fakeFileContent', 'fakeFileContent');
sinon.assert.match(actual, 'fakeFileContent');
sinon.assert.calledWithExactly(fs.mkdir, 'fakeFileContent', sinon.match.func);
sinon.assert.calledWithExactly(fs.createReadStream, 'fakeFileContent');
sinon.assert.calledWithExactly(unzipper.Extract, { path: 'fakeFileContent' });
sinon.assert.calledOnce(rs.pipe);
sinon.assert.calledWithExactly(rs.on, 'close', sinon.match.func);
});
});

测试结果:

69616649
✓ should pass

1 passing (7ms)
----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |   81.82 |      100 |      75 |   81.82 |                   
index.js |   81.82 |      100 |      75 |   81.82 | 13-14             
----------|---------|----------|---------|---------|-------------------

Answer 3

我是ava的新手，所以可能是错误的

proxyquire('../../../src/helpers/file/unZip')// actual function file
ava('69616649', () => {
ava.afterEach(() => {
sinon.restore();
});
ava.serial('should pass', async () => {
sinon.stub(fs, 'mkdir').callsFake((path, callback) => {
callback();
});
const rs = {
pipe: sinon.stub().returnsThis(),
on: sinon.stub().callsFake(function (event, callback) {
if (event === 'close') {
callback();
}
}),
};
sinon.stub(fs, 'createReadStream').returns(rs);
sinon.stub(unzipper, 'Extract');
const actual = await unZip('fakeFileContent', 'fakeFileContent');
sinon.assert.match(actual, 'fakeFileContent');
sinon.assert.calledWithExactly(
fs.mkdir,
'fakeFileContent',
sinon.match.func
);
sinon.assert.calledWithExactly(fs.createReadStream, 'fakeFileContent');
sinon.assert.calledWithExactly(unzipper.Extract, {
path: 'fakeFileContent',
});
sinon.assert.calledOnce(rs.pipe);
sinon.assert.calledWithExactly(rs.on, 'close', sinon.match.func);
});
});