Confused about HTTPs request regarding supertest and mocha

So I'm a bit confused about supertest. I'm currently attempting to write a test suite for the back end of a web portal using Mocha and Supertest, and I'm very much still learning the ropes. I've been testing off of a simple HTTPS server that I initiate with javascript and node.js, then running mocha tests with supertest assertions.

All my GET tests work well- if I attempt to get a file that I know is there, it completes the 200 expect assertion. If I attempt to get a file that I know is invalid, it completes the 404 expect assertion. However, when I run PUT, POST or DEL as functions of my supertest object, it doesn't seem to do anything. For example:

it('should delete json', function(done){
request
  .del('/files/package.json')
  .end(function(err, res){
    if (err) return done(err);
    done();
  });
});

does not actually delete the file, yet passes the test. If I run a 404 expect assertion after the DEL, the test then fails.

I am confused whether I'm just completely missing something from my code or if the commands don't do what I think they do, or if I've just misunderstood how this testing framework works. Sorry if it's a stupid question, very new at this.

via user3817846