Wicket provides utility class FormTester that is expressly designed to test Wicket forms. A new FormTester is returned by WicketTester’s method newFormTester(String, boolean) which takes in input the page-relative path of the form we want to test and a boolean flag indicating if its form components must be filled with a blank string:

//...
//create a new form tester without filling its form components with a blank string
FormTester formTester = tester.newFormTester("form", false);
//...

FormTester can simulate form submission with method submit which takes in input as optional parameter the submitting component to use instead of the default one:

//...
//create a new form tester without filling its form components with a blank string
FormTester formTester = tester.newFormTester("form", false);
//submit form with default submitter
formTester.submit();
//...
//submit form using inner component 'button' as alternate button
formTester.submit("button");

If we want to submit a form with an external link component we can use method submitLink(String path, boolean pageRelative) specifying the path to the link.

In the next paragraphs we will see how to use WicketTester and FormTester to interact with a form and with its children components.

Setting form components input

The purpose of a HTML form is to collect user input. FormTester comes with the following set of methods that simulate input insertion into form’s fields:

• setValue(String path, String value): inserts the given textual value into the specified component. It can be used with components TextField and TextArea. A version of this method that accepts a component instance instead of its path is also available.

• setValue(String checkboxId, boolean value): sets the value of a given CheckBox component.

• setFile(String formComponentId, File file, String contentType): sets a File object on a FileUploadField component.

• select(String formComponentId, int index): selects an option among a list of possible options owned by a component. It supports components that are subclasses of AbstractChoice along with RadioGroup and CheckGroup.

• selectMultiple(String formComponentId, int[] indexes): selects all the options corresponding to the given array of indexes. It can be used with multiple-choice components like CheckGroup or ListMultipleChoice.

setValue is used inside method insertUsernamePassword to set the username and password fields of the form used in project StatelessLoginForm:

protected void insertUsernamePassword(String username, String password) {
    //start and render the test page
    tester.startPage(HomePage.class);
    FormTester formTester = tester.newFormTester("form");
    //set credentials
    formTester.setValue("username", username);
    formTester.setValue("password", password);      
    //submit form
    formTester.submit();
}

Testing feedback messages

To check if a page contains one or more expected feedback messages we can use the following methods provided by WicketTester:

• assertFeedback(String path, String… messages): asserts that a given panel contains the specified messages

• assertInfoMessages(String… expectedInfoMessages): asserts that the expected info messages are rendered in the page.

• assertErrorMessages(String… expectedErrorMessages): asserts that the expected error messages are rendered in the page.

assertInfoMessages and assertErrorMessages are used in the test case from project StatelessLoginForm to check that form generates a feedback message in accordance with the login result:

@Test
void testMessageForSuccessfulLogin(){
    inserUsernamePassword("user", "user");  
    tester.assertInfoMessages("Username and password are correct!");
}   
    
@Test
void testMessageForFailedLogin (){
    inserUsernamePassword("wrongCredential", "wrongCredential");        
    tester.assertErrorMessages("Wrong username or password");
}

Testing models

Component model can be tested as well. With method assertModelValue we can test if a specific component has the expected data object inside its model.

This method has been used in the test case of project ModelChainingExample to check if the form and the drop-down menu share the same data object:

@Test
void testFormSelectSameModelObject(){
    PersonListDetails personListDetails = new PersonListDetails();
    DropDownChoice dropDownChoice = (DropDownChoice) personListDetails.get("persons");
    List choices = dropDownChoice.getChoices();
    //select the second option of the drop-down menu
    dropDownChoice.setModelObject(choices.get(1));
    
    //start and render the test page
    tester.startPage(personListDetails);        
    //assert that form has the same data object used by drop-down menu
    tester.assertModelValue("form", dropDownChoice.getModelObject());
}