HtmlUnitDriver driver = new HtmlUnitDriver(false);
Otherwise you'll find this exception
org.openqa.selenium.ElementNotVisibleException: You may only interact with visible elements
(I'm using HtmlUnit 2.12)
There may be a way around this to do with jQuery versions, I've read.
Otherwise, PhantomJs seems to be another solution.
java bootstrap java-testing selenium
Page 1 of 1