Writing a test function for function inside a function with callback in javascript

I have a function fulltest as follows in abc.js file.

fullTest: function (fileList, callback) {
async.eachOfLimit(fileList, 200, function (file, key, cb) {
            var path = utils.files.relativePath(file);
            file.relativePath = path;
            var values = utils.type.getPathValues(file.relativePath);

            // checks if sub/ses-id in filename matches with ses/sub directory file is saved

            var pathValues = values[0];
            var fileValues = values[1];

            if (fileValues.sub !== null || fileValues.ses !== null){
              if (fileValues.sub !== pathValues.sub){
                self.issues.push(new Issue({
                    code: 57,
                    evidence: "File: " + file.relativePath + " is saved in incorrect subject directory as per sub-id in filename.",
                    file: file
                }));
              }

              if (fileValues.ses !== pathValues.ses){
                self.issues.push(new Issue({
                    code: 58,
                    evidence: "File: " + file.relativePath + " is saved in incorrect session directory as per ses-id in filename.",
                    file: file
                }));
              }
            }
}

Now in another file testabc.js i want to test the functionality of above function i.e when sub and ses id mismatch in the filename.

hence the code is as follows:

var issues = [{code: 57}, {code: 58}];
    var code57_seen = false;
    var code58_seen = false;
    it('should return if sub and ses doesnt match', function () {
        var files = ['/sub-22/ses-1/func/sub-22_ses-1_task-rest_acq-prefrontal_physio.tsv.gz',
            '/sub-22/ses-1/func/sub-23_ses-1_task-rest_acq-prefrontal_physio.tsv.gz', '/sub-22/ses-1/func/sub-22_ses-2_task-rest_acq-prefrontal_physio.tsv.gz', '/sub-25/ses-2/func/sub-22_ses-1_task-rest_acq-prefrontal_physio.tsv.gz'];
        var callback = function (issues, summary) {
            for (var i in issues) {
                if (issues[i]['code'] === 57) {
                    code57_seen = true;
                }
                else if (issues[i]['code'] === 58) {
                    code58_seen = false;
                }
            }
            assert(code57_seen);
            assert(code58_seen);
            console.log(issues[i]['code'] === 58);
        };
        // assert(validatorss.bids.fullTest(files, callback));
        abc.fullTest(files, callback);
        }); 

The github link to this file is http://ift.tt/2uwHd7w. I am not sure how this test should be written to test a function from another file. Can someone point what is the mistake i am doing or how i should approach at this problem ..?