How to stub isFile from fs.statSync

Question

I am writing a unit test for file and path manipulations, but I cannot stub isFile in fs.statSync(filePath).isFile() .

I am getting the following error:

ReferenceError: isFile is not defined

My code is :

const readFiles = fs.readdirSync(directoryPath);
      readFiles.map(file => {
        filePath = path.resolve(process.cwd(), `${directoryPath}/${file}`);
        const isFile = fs.statSync(filePath).isFile();
        if (!isFile) {
          const filesList = fs.readdirSync(filePath).map(fileName => file + '/' + fileName);
          files = [
            ...files,
            ...filesList,
          ];
        } else {
          files = fs.readdirSync(directoryPath);
        }
      });

here is my before test code, to create the stubs and assign to rewired :

beforeEach(() => {
    helpers.__set__({
      'fs.statSync': sinon.stub().returns(true),
      isFile: sinon.stub().returns(true),
      'path.resolve': sinon.stub().returns('/a/b/c'),
    });
  });

please advise

Answer 1

If your stub for fs.statSync works as intended, it provides true. So you can't call isFile on it.

So I suppose you can simply mock a function isFile in the object provided by statSync that would return true:

'fs.statSync': sinon.stub().returns({ isFile: () => true})