Question

In Vaadin as you may know overrided generateCell method is only called when Table needs to build its visible content. So When I write a JUnit Test for this class i couldnt trigger the generateCell method and test it. How can I test this any ideas? Or do I have to use a GUI test tool forthis (which I dont want to because it has quite expensive license)

public class AttributeColumnGenerator implements Table.ColumnGenerator {    
@Override
public Object generateCell(Table source, Object itemId, Object columnId) {
    //lots of code here to be tested
}
}

Answer 1

From my understanding of the question, I don’t think you need to have a GUI test tool here.

There’s my idea for simple testing :

1. Create an instance AttributeColumnGenerator.
2. Create an table.
3. Add an Item to the table
4. call generateCell with an columnId and itemId.
5. Do the appropriate assert on the Component returned by the method.

Here’s a snippet of my idea

First my ColumnGenerator who only create a Label with the value of the cell.

public class AttributeColumnGenerator implements Table.ColumnGenerator {

public Object generateCell(Table source, Object itemId, Object columnId) {

    String textToDisplay  = (String)source.getItem(itemId).getItemProperty(columnId).getValue();
    return new Label(textToDisplay);
}    

}

And the test method

    @Test
    public void attributeColumnGenratortest()
    {

        AttributeColumnGenerator columnGenerator = new AttributeColumnGenerator();

        Table table = new Table();
        String columnId = "test";
        table.addContainerProperty(columnId, String.class, "");

        String itemId = "item1";
        Item item = table.addItem(itemId);
        item.getItemProperty(columnId).setValue("Value of item1");


        Label generateObject = (Label)columnGenerator.generateCell(table, itemId, columnId);

        // Assert any properties of the returned Component.
        // In this snippet, I only printOut the boolean comparaison.
        System.out.println( "Value of item 1".equals(generateObject.getValue()));
    }

Maybe it’s not the best solution, but it’s works.

Hope it’s help!

Regards.