Test if input is Alphanumeric or not with JasmineJS

Question

My last question for today is not really a question, I would like to have your opinion about this JasmineJS test code I created to test if user entered alphanumeric or not.

I have an HTML input box called username:

Username: <input type="text" name="username" id="username" class="input" value="testinput" />

I created a Javascript function to filter user input if the input is alphanumeric or not.

function acceptOnlyAlphanumeric() {
  var usernameInput = document.register.username.value;

  if(!/^[a-zA-Z0-9]+$/.test(usernameInput)) {
    console.log("Please enter only numbers and letters. No special character!")
    return true;
  }
    return false;
}

Inside my JasmineJS folder I created a service file to test the filter user input feature. My service goes like this:

Services = {
  userFilter : function () {
    var usernameInput = 'ThisIsAnAlphanumeric112233';

    if(!/^[a-zA-Z0-9]+$/.test(usernameInput)) {
      console.log("Please enter only numbers and letters. No special character!")
      return true;
    }
      return false;
  }
};

Then my jasmine script goes like this:

describe("Test if user enters an acceptable user input which is alphanumeric", function () {
    it("Should test if user enters alphanumeric or not", function () {
      expect(Services.userFilter()).toEqual(false);
    });
  });

Everythings works just fine, but I am concerned about the validity of the test. Bottom question is, is this the correct way to test the javascript function with JasmineJS? Thanks

Answer 1

A good test, as well as good code is modular. You are just testing if your code returns false. To check if your code is correctly testing if a string is alphanumeric you would want to test it against strings that are alphanumeric as well as strings that aren't alphanumeric. I would pass the string into the function you are testing.

Services = {
  userFilter : function (userInput) {
  //var usernameInput = 'ThisIsAnAlphanumeric112233';
  if(!/^[a-zA-Z0-9]+$/.test(userInput)) {
    console.log("Please enter only numbers and letters. No special character!")
  return true;
  }
  return false;
  }
};




   describe("Test if user enters an acceptable user input which is alphanumeric", function () {
    it("Should test if user enters alphanumeric or not", function () {
      expect(Services.userFilter('ThisIsAnAlphanumeric112233')).toEqual(true);
    });
  });
describe("Test if user enters an acceptable user input which is alphanumeric", function () {
    it("Should test if user enters alphanumeric or not", function () {
      expect(Services.userFilter('ThisIsAnAlphanumeric#$$@@')).toEqual(false);
    });
  });