Proxyquire：不能存根fs.readFileSync

Question

我似乎無法在fj上從NodeJS核心上存取readFileSync。下面的代碼隔離了這個問題。通過運行結果摩卡測試在以下幾點：

> 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) 

這裏的測試/ 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 ... 
    }); 
}); 

而這裏的sut.js，這是該模塊進行測試：

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

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

該項目的文件夾結構爲：

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

test.js可以通過從提示中執行mocha tests/test.js來運行。

我注意到幾年前在Github上發佈了一個關於看起來類似的問題，但是我不知道它是相同的問題還是不同的問題。這裏的鏈接：

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

萬一有幫助，這些都是我的package.json文件的依賴關係。我嘗試使用類似版本的依賴關係爲代理：

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

任何幫助非常感謝！

Answer 1

您不需要存根fs.readFileSync()如果使用proxyquire來取代它是也（事實上，磕碰fs.readFileSync()導致您的問題，因爲它打破雙方require()和proxyquire）。 @robertklep

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'); 
    }); 

});