Want to asser text present in Page Source Code or not

//Only way you can read a variable is using javascript//with <code>executeScript</code> method as shown bellow.private void test(){    String script = "return rlSerial;";    String value = (String) ((JavascriptExecutor)driver).executeScript(script);    System.out.println(value);    //Use assert here}

You can just loop through all the SCRIPT tags and search for the desired text.

List<WebElement> scriptTags = driver.findElements(By.tagName("script"));for (WebElement scriptTag : scriptTags){    if (scriptTag.getAttribute("innerHTML").contains("var rlSerial = '1058358';"))    {        // assertTrue()        break;    }}

EDIT:I just ran the code below and it worked fine for me... must be something on your end.

driver.get("http://www.google.com");String searchText = "document.body.style.visibility";List<WebElement> scriptTags = driver.findElements(By.tagName("script"));for (WebElement scriptTag : scriptTags){    String text = scriptTag.getAttribute("outerHTML");    if (text.contains(searchText))    {        System.out.println("Found it: " + text);        // your assertTrue(...) goes here        break;    }}

Console:

Found it: <script>if(google.j.b)document.body.style.visibility='hidden';</script>