var testtest() {
    somecode bla bla bla;
    somecode bla bla bla;
    somecode bla bla bla;
    return false;
}

alert("Hello World!");
window.location = loc.replace(testtest, "aaaaa");

alert("Hello World!");
loc.replace(testtest, "aaaaa");

alert("Hello World!");
testtest= "aaaaa";

alert("Hello World!");
var str="testtest";
var n=str.replace("testtest","aaaaa");

alert("Hello World!");
function pacifyGlobalFunction(testtest) {
Object.defineProperty(
    window,
    testtest,
    {
        value: function () {},
        configurable: true // permit future Object.defineProperty
    }
);
}

alert("Hello World!");
Object.defineProperty(window, 'testtest', {
    value: function(){/*This function cannot be overridden*/}
});

alert("Hello World!");
var actualCode = '(' + function() {
    window.testtest = null;
} + ')();';
var script = document.createElement('script');
script.textContent = actualCode;
(document.head||document.documentElement).appendChild(script);
script.parentNode.removeChild(script);

function testtest() {}

window.testtest = function () {};

delete window.testtest;

function pacifyGlobalFunction(functionName) {
    Object.defineProperty(
        window,
        functionName,
        {
            value: function () {},
            configurable: true // permit future Object.defineProperty
        }
    );
}

function testMe() {
   alert("Hi");
}

function testMe() {}