How to test one function of a class and how to avoid some code when test a function?

Question

How to test one function of a class and how to avoid some code when test a function?

Sample code:

function TestClass() {
  var this.name = 'test';
  var this.host = '...';
  var this.port = '...';
  //...
  this.connection = this.createConnection(....);
}

TestClass.prototype.testFunc = function(data) {
  if(data == this.name) {
     return true;
  } else {
     return false;
  }
}

Testclass.prototype.createConnection = function (...) {
   //some code
  //a real HTTP connection will be created
  //some code
}

Now I want to test testFunc, it has a class variable this.name, so I have to create a TestClass instance. But if I create TestClass instance, a real HTTP connection will be created. How can I avoid this real HTTP connection when testing?

In situation like this, how can I write the test code?

node.js
testing
mocha

Answer 1

Try to simply re-define createConnection in your test, before you instantiate TestClass.

TestClass.prototype.createConnection = function() {
    console.log("Called redefined createConnection");
}

Answer 2

You should mock the dependency that make the request not your class you wanna test. Take a look at this nock, a HTTP mocking and expectations library