Proxyquire:无法存储fs.readFileSync

Question

我似乎无法将readFileSync从NodeJS核心存根到fs上。下面的代码隔离了这个问题。通过Mocha运行测试结果如下：

> mocha tests/test.js

      Some description
        1) "before all" hook


      0 passing (15ms)
      1 failing

      1) Some description "before all" hook:
         TypeError: Cannot read property 'charCodeAt' of undefined
          at Object.stripBOM (internal/module.js:48:14)
          at Object.require.extensions.(anonymous function) (node_modules/proxyquire/lib/proxyquire.js:276:43)
          at Proxyquire._withoutCache (node_modules/proxyquire/lib/proxyquire.js:179:12)
          at Proxyquire.load (node_modules/proxyquire/lib/proxyquire.js:136:15)
          at Context.<anonymous> (tests/test.js:12:15)

下面是测试/test.js

var proxyquire = require('proxyquire'),
    sinon = require('sinon'),
    fs = require('fs'),
    sut;

describe('Some description', function () {
    var readFileSyncStub;

    before(function () {
        readFileSyncStub = sinon.stub(fs, 'readFileSync');
        readFileSyncStub.withArgs('someFile.js', { encoding: 'utf8' }).returns('some text');
        sut = proxyquire('../sut', { fs: { readFileSync: readFileSyncStub } }); // Exception encountered somewhere in here ...
    });

    after(function () {
        fs.readFileSync.restore(); // This is executed ...
    });

    it('Some it', function () {
        // This never happens ...
    });
});

下面是sut.js，这是正在测试的模块：

var fs = require('fs'); // The code in this file is never executed ...

module.exports = function () {
    return fs.readFileSync('someFile.js', { encoding: 'utf8' });
};

该项目的文件夹结构是：

./sut.js
./package.json
./tests/test.js

test.js可以通过从提示符执行mocha tests/test.js来运行。

我注意到，几年前，有一篇文章报道了一个类似的问题，但我不知道是同一个问题，还是另一个问题。下面是链接：

https://github.com/thlorenz/proxyquire/issues/12

如果有帮助，这些是我的package.json文件中的依赖项。我尝试使用类似于proxyquire的依赖项的版本：

{
  ...
  "devDependencies": {
    "jshint": "^2.9.5",
    "jslint": "^0.11.0",
    "mocha": "~3.1",
    "proxyquire": "^1.8.0",
    "sinon": "~1.9"
  },
  "dependencies": {}
  ...
}

任何帮助都是非常感谢的！

Answer 1

如果您也使用fs.readFileSync()来替换它，则不需要使用存根proxyquire (实际上，顽固的fs.readFileSync()会导致您的问题，因为它破坏了require()和proxyquire)。

试试这个：

describe('Some description', function () {
  var readFileSyncStub;

  before(function() {
    readFileSyncStub = sinon.stub()
                            .withArgs('someFile.js', { encoding: 'utf8' })
                            .returns('some text');
    sut = proxyquire('../sut', { fs : { readFileSync : readFileSyncStub } });                         
  });

  it('Some it', function () {
    let value = sut();
    assert.equal(value, 'some text');
  });

});