Things to notice when testing form on Wicket

Wicket, a Java-based web application framework, provides powerful tester to test the application. The tester can simulate activities of users on the web application. The form tester is a component of the tester, which use to test form behavior on the page. However, there are something one need to notice when using the form tester.

Let's look at this example.
We test a form in the Checkout page, which looks like this

Name
Street
Zip code
City
State	Alabama Nebraska

The test code is

FormTester formTester = tester.newFormTester("form");
formTester.setValue("name", "Philip");
formTester.setValue("street", "Main Street");
formTester.setValue("zipcode", "96822");
formTester.setValue("city", "Anchorage");
formTester.setValue("state-wmc:state", "Alaska");
formTester.submit();
tester.assertRenderedPage(Index.class);

But when run the test, the last assertion indicate that it still in the Checkout page. Did you find anything wrong? The problem lies in

formTester.setValue("state-wmc:state", "Alaska");

And the fix is

formTester.select("state-wmc:state", 1);

The reason is that, FormTester.setValue() method cannot be used to set the value of selection field, thus the "state-wmc:state" field is not filled, so when the form is submitted, an error of invalid value occurs. This is an usual mistake when using FormTester.

Additionally, in order to find out what goes wrong when the test fail, we can use the Tester.assertErrorMessages(String[]) to see the error message.