To test static methods in Salesforce, we have to call the method along with the controller name, not with the object of the controller.

Example:


Apex Class:


public class example
{
    public static integer add(integer a, integer b)
    {
        return (a+b);  
    }


    static testMethod void testforExample()
    {
        example.add(8,9);
    }
}