magento2 – Magento 2: knockout function automatically call without click

I have call one function on button click but right now its call on page load automatically. It should be call only when click on button.
Knockout js

 define((
  'ko',
  'uiComponent'
), function (ko,Component) {
  'use strict';
   return Component.extend({
      firstname:ko.observable(),
      initialize:function(config){
          this._super();
      },
      getTest:function(){
        console.log('somi');
      }
   });  
});

HTML

<div data-bind="text: firstname"></div>
<button data-bind="click: getTest()">click me</button>

is any idea, please share.