GWTTestCase: Testing a Private Method

Question

I am new to GWT / Java and need some ideas on how to solve this (seems like it should be) simple problem.

I have a GWT object and I am trying to test a private method:

public class BarChart extends FlowPanel {

    public BarChart() {
        super();
        privateMethod();
    }

    privateMethod() { 
        //want to test this 
    }
}

I've tried JUnit but it needs to be a GWTTestCase since this object needs GWT.create(), and I've tried reflection but GWTTestCase doesn't support it.

Answer 1

In GWT client (included GWTTestCase), you can call private or protected methods using JSNI, this is known as the violator pattern

Given a class with a private method

package com.example;
public class MyClass {
  private MyObjectReturn myMethod(MyObjectParam param) {
     return null
  }
}

Create a jsni method and access it

native MyObjectReturn myViolatorMethod(MyClass instance, MyObjectParam param) /*-{
  return instance.@com.example.MyClass::myMethod(*)(param);
}-*/;