app.js

// Common JavaScript code across your application goes here.

$("p").click(function() {
  $(this).replaceWith("<input type='text' name='testing' />")
});

test.js

jspec.describe("visiting '/router'", function() {
  it("should return text", function() {
    var resp = merb.visit("/testage");
    $("p").click();
    expect($("p").length).to("==", 0);
    expect($("input").attr("name")).to("==", "testing")
  });
});