# mm, mock mate [![NPM version][npm-image]][npm-url] [![Node.js CI](https://github.com/node-modules/mm/actions/workflows/nodejs.yml/badge.svg)](https://github.com/node-modules/mm/actions/workflows/nodejs.yml) [![Test coverage][codecov-image]][codecov-url] [![npm download][download-image]][download-url] [npm-image]: https://img.shields.io/npm/v/mm.svg?style=flat-square [npm-url]: https://npmjs.org/package/mm [codecov-image]: https://codecov.io/github/node-modules/mm/coverage.svg?branch=master [codecov-url]: https://codecov.io/github/node-modules/mm?branch=master [download-image]: https://img.shields.io/npm/dm/mm.svg?style=flat-square [download-url]: https://npmjs.org/package/mm An simple but flexible **mock(or say stub)** package, mock mate. ## Install ```bash npm install mm --save-dev ``` ## Usage ```js var mm = require('mm'); var fs = require('fs'); mm(fs, 'readFileSync', function(filename) { return filename + ' content'; }); console.log(fs.readFileSync('《九评 Java》')); // => 《九评 Java》 content mm.restore(); console.log(fs.readFileSync('《九评 Java》')); // => throw `Error: ENOENT, no such file or directory '《九评 Java》` ``` ### Support spy If mocked property is a function, it will be spied, every time it called, mm will modify `.called`, `.calledArguments` and `.lastCalledArguments`. For example: ```js const target = { async add(a, b) { return a + b; }, }; mm.data(target, 'add', 3); assert.equal(await target.add(1, 1), 3); assert.equal(target.add.called, 1); assert.deepEqual(target.add.calledArguments, [[ 1, 1 ]]); assert.deepEqual(target.add.lastCalledArguments, [ 1, 1 ]); assert.equal(await target.add(2, 2), 3); assert.equal(target.add.called, 2); assert.deepEqual(target.add.calledArguments, [[ 1, 1 ], [ 2, 2 ]]); assert.deepEqual(target.add.lastCalledArguments, [ 2, 2 ]); ``` If you only need spy and don't need mock, you can use `mm.spy` method directly: ```js const target = { async add(a, b) { await this.foo(); return a + b; }, async foo() { /* */ }, }; mm.spy(target, 'add'); assert.equal(await target.add(1, 1), 2); assert.equal(target.add.called, 1); assert.deepEqual(target.add.calledArguments, [[ 1, 1 ]]); assert.deepEqual(target.add.lastCalledArguments, [ 1, 1 ]); assert.equal(await target.add(2, 2), 4); assert.equal(target.add.called, 2); assert.deepEqual(target.add.calledArguments, [[ 1, 1 ], [ 2, 2 ]]); assert.deepEqual(target.add.lastCalledArguments, [ 2, 2 ]); ``` ## API ### .error(module, propertyName, errerMessage, errorProperties) ```js var mm = require('mm'); var fs = require('fs'); mm.error(fs, 'readFile', 'mock fs.readFile return error'); fs.readFile('/etc/hosts', 'utf8', function (err, content) { // err.name === 'MockError' // err.message === 'mock fs.readFile return error' console.log(err); mm.restore(); // remove all mock effects. fs.readFile('/etc/hosts', 'utf8', function (err, content) { console.log(err); // => null console.log(content); // => your hosts }); }); ``` ### .errorOnce(module, propertyName, errerMessage, errorProperties) Just like `mm.error()`, but only mock error once. ```js const mm = require('mm'); const fs = require('fs'); mm.errorOnce(fs, 'readFile', 'mock fs.readFile return error'); fs.readFile('/etc/hosts', 'utf8', function (err, content) { // err.name === 'MockError' // err.message === 'mock fs.readFile return error' console.log(err); fs.readFile('/etc/hosts', 'utf8', function (err, content) { console.log(err); // => null console.log(content); // => your hosts }); }); ``` ### .data(module, propertyName, secondCallbackArg) ```js mm.data(fs, 'readFile', new Buffer('some content')); // equals fs.readFile = function (...args, callback) { callback(null, new Buffer('some content')) }; ``` ### .dataWithAsyncDispose(module, propertyName, promiseResolveArg) Support [Symbol.asyncDispose](https://www.totaltypescript.com/typescript-5-2-new-keyword-using) ```js mm.dataWithAsyncDispose(locker, 'tryLock', { locked: true, }); // equals locker.tryLock = async () => { return { locked: true, [Symbol.asyncDispose](): async () => { // do nothing }, }; } ``` Run test with `await using` should work: ```js mm.dataWithAsyncDispose(locker, 'tryLock', { locked: true, }); await using lock = await locker.tryLock('foo-key'); assert.equal(lock.locked, true); ``` ### .empty(module, propertyName) ```js mm.empty(mysql, 'query'); // equals mysql.query = function (...args, callback) { callback(); } ``` ### .datas(module, propertyName, argsArray) ```js mm.datas(urllib, 'request', [new Buffer('data'), {headers: { foo: 'bar' }}]); // equals urllib.request = function (...args, callback) { callback(null, new Buffer('data'), {headers: { foo: 'bar' }}); } ``` ### .syncError(module, propertyName, errerMessage, errorProperties) ```js var mm = require('mm'); var fs = require('fs'); mm.syncError(fs, 'readFileSync', 'mock fs.readFile return error', {code: 'ENOENT'}); // equals fs.readFileSync = function (...args) { var err = new Error('mock fs.readFile return error'); err.code = 'ENOENT'; throw err; }; ``` ### .syncData(module, propertyName, value) ```js mm.syncData(fs, 'readFileSync', new Buffer('some content')); // equals fs.readFileSync = function (...args) { return new Buffer('some content'); }; ``` ### .syncEmpty ```js mm.syncEmpty(fs, 'readFileSync'); // equals fs.readFileSync = function (...args) { return; } ``` ### .restore() ```js // restore all mock properties mm.restore(); ``` ### .http.request(mockUrl, mockResData, mockResHeaders) and .https.request(mockUrl, mockResData, mockResHeaders) ```js var mm = require('mm'); var http = require('http'); var mockURL = '/foo'; var mockResData = 'mock data'; var mockResHeaders = { server: 'mock server' }; mm.http.request(mockURL, mockResData, mockResHeaders); mm.https.request(mockURL, mockResData, mockResHeaders); // http http.get({ path: '/foo' }, function (res) { console.log(res.headers); // should be mock headers var body = ''; res.on('data', function (chunk) { body += chunk.toString(); }); res.on('end', function () { console.log(body); // should equal 'mock data' }); }); // https https.get({ path: '/foo' }, function (res) { console.log(res.headers); // should be mock headers var body = ''; res.on('data', function (chunk) { body += chunk.toString(); }); res.on('end', function () { console.log(body); // should equal 'mock data' }); }); ``` ### .http.requestError(mockUrl, reqError, resError) and .https.requestError(mockUrl, reqError, resError) ```js var mm = require('mm'); var http = require('http'); var mockURL = '/foo'; var reqError = null; var resError = 'mock res error'; mm.http.requestError(mockURL, reqError, resError); var req = http.get({ path: '/foo' }, function (res) { console.log(res.statusCode, res.headers); // 200 but never emit `end` event res.on('end', fucntion () { console.log('never show this message'); }); }); req.on('error', function (err) { console.log(err); // should return mock err: err.name === 'MockHttpResponseError' }); ``` ### .classMethod(instance, method, mockMethod) ```js class Foo { async fetch() { return 1; } } const foo = new Foo(); const foo1 = new Foo(); mm.classMethod(foo, 'fetch', async () => { return 3; }); assert(await foo.fetch() === 3); assert(await foo1.fetch() === 3); ``` ## License [MIT](LICENSE) ## Contributors |[

_fengmk2](https://github.com/fengmk2)
|[

_dead-horse](https://github.com/dead-horse)
|[

_alsotang](https://github.com/alsotang)
|[

_popomore](https://github.com/popomore)
|[

_{semantic-release-bot}](https://github.com/semantic-release-bot)
|[

_gemwuu](https://github.com/gemwuu)
| | :---: | :---: | :---: | :---: | :---: | :---: | |[

_paranoidjk](https://github.com/paranoidjk)
|[

_nightink](https://github.com/nightink)
|[

_killagu](https://github.com/killagu)
|[

_gxkl](https://github.com/gxkl)
|[

_iyuq](https://github.com/iyuq)
|[

_atian25](https://github.com/atian25)
| [

_xavierchow](https://github.com/xavierchow)
|[

_whxaxes](https://github.com/whxaxes)
This project follows the git-contributor [spec](https://github.com/xudafeng/git-contributor), auto updated at `Sat Dec 09 2023 11:34:46 GMT+0800`.

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