Release 0.1

I have written a test for fs.rename() when oldPath=newPath.

1. I started by looking at the list of fs methods in Node.js Documentation and found one (rename) that is clear to me.
2. After forking filer to my account, I looked at the existing tests and found out that there is no tests for the case when oldPath=newPath.
3. I wrote a test expecting that a path will be overwritten (as it is stated in Linux Programmer's Manual). By the way, Node.js Docs also state "in the case that newPath already exists, it will be overwritten.
4. Unfortunately, my test failed. But after numerous experiments and attempts to fix the test, I came to the conclusion that this method might actually work differently.
5. This is why I rewrote my test in a way that it expects failure in method execution. And it passed.

I still am not sure how rename() should work when oldPath=newPath, but it fails in this case. On the other hand, I learned how to create and run tests for Node.js modules.

Here is a final version of my test:

it('should fail to overwrite an existing file to itself', function (done) {

var fs = util.fs();

fs.open('/myfile', 'w+', function (error, fd) {

if (error) throw error;

fs.close(fd, function (error) {

if (error) throw error;

fs.rename('/myfile', '/myfile', function (error) {

expect(error).to.exist;

expect(error.code).to.equal('EEXIST');

done();

});

});

});

});

I created an issue stating that this test was missing: https://github.com/filerjs/filer/issues/493 and pull request with a test: https://github.com/filerjs/filer/pull/502

I also reveiwed peer's pull request: https://github.com/filerjs/filer/pull/539

describe('fsPromises.Write', function () {

it('should write, read a utf8 file without specifying utf8 in writeFile', function () {

//var fs = util.fs();

//var contents = 'This is a file.';

var fsPromises = util.fs().promises;

return fsPromises.writeFile('/myfile', { encoding: 'utf8' })

.then(() => {

return fsPromises.readFile('/myfile', 'utf8')

.catch((error) => {

expect(error).not.to.exist;

//expect(data).to.equal(contents);

//done();

});

});

});

});

After looking at this test, I went to existing tests and found out that this test already exists. Also, in return fsPromises.writeFile('/myfile' , { encoding: 'utf8' }) data parameter is missing.
I let pull request creator know about my comments.

fs.readFile() and fs.readFileSync()

Today I would like to discuss fs.readFile() and fs.readFileSync().

fs.readFile(path[, options], callback)

fs.readFile() is used to asynchronously read files. It takes up to 3 parameters:
path - can be string, Buffer, URL or integer. It specifies filename or file descriptor.
options - can be encoding string or null (example: 'utf8')
               or flag string (examples: 'a', 'as', 'w+'). Full list you can see here.
callback function takes 2 parameters:
Error err
and string or Buffer data that stores the contents of the file.

When you use this function, remember the following rules:

• If you don't specify the encoding, the raw buffer is returned.
• If you specify file descriptor, it has to include reading possibility.
• This function buffers the entire file. If you care about memory, you might want to use another way of reading files.

Here is a sample code:

fs.readFile('demofile1.html', function(err, data) {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write(data);
    res.end();
}

fs.readFileSync(path[, options])

fs.readFileSync() is used to synchronously read files. It takes up to 2 parameters:

path - can be string, Buffer, URL or integer. It specifies filename or file descriptor.
options - can be encoding string or null (example: 'utf8')
                           or flag string (examples: 'a', 'as', 'w+'). Full list you can see here.

Rules mentioned about fs.readFile() also apply to fs.readFileSync().

Here is a sample code:

fs.readFile('demofile1.html');

Sources:
https://nodejs.org/api/fs.html#fs_fs_readfile_path_options_callback
https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options
https://www.w3schools.com/nodejs/nodejs_filesystem.asp