In this activity, you will write code to mock and spy on the fs module to ensure that it’s called when expected with the correct arguments.
Open the starter/fileIO.js file and take a moment to examine its contents.
This file exports a FileIO constructor function with methods for reading and writing to the file system.
The read and write methods use the synchronous versions of fs.readFile and fs.writeFile, so no callback function is required.
Open starter/tests/fileIO/test.js and add code to mock the fs module its readFileSync and writeFileSync methods so that they don’t read from and write to the file system.
Make sure that the readFileSync and writeFileSync methods are called with the correct arguments when the FileIO.prototype.read and FileIO.prototype.write methods are called.
FileIO.prototype.append method that should append to a given file. Then update the starter/fileIO.js file to include this method using the fs.appendFileSync method.