Sinon Stub is not throwing an error when fs.readFileSynch also throws an error

Question

After going through all related issues regarding stubbing readFile/Sync with Sinon /Chai/ Mocha, the test is failing.

There's a basic getFile function that retrieves a file:

function getFile(path) {
const file = fs.readFileSync(path, "utf8)
return file;
}

module.exports = {getFile}

and I want to create a test where getFile should throw an error if fs.readFileSync also throws an error:

it('should throw an error if fs.readFileSync throws an error', () => {

I tried:

it('should throw an error if fs.readFileSync throws an error', () => {
  const error = new Error('some error message')
  const myStub = sinon.stub(fs, "readFileSync")
    myStub.throws(error)
  const filePath = "/Project/test.js" 
  const gFile = index.getFile(filePath)

  try {
    if(myStub.error === true) {
          gFile(error)       
  } catch (error) {
    expect(myStub).to.throw(error)

What I got was:

1 failing Error: some error message at Context. at process.processImmediate

Answer 1

Try putting your error function in the Sinon throw method as below.

myStub.throws(new Error('some error message'));