When writing unit tests for controller extension and custom controller classes, you can set query parameters that can then be used in the tests. For example, the following custom controller and markup is based on the example from Controller Methods, but has been extended to expect the following query parameter in the URL for the page: ?qp=yyyy. A test method class follows, which exercises the functionality of this page:

Custom Controller

 
public class thecontroller {
            private String firstName;
            private String lastName;
            private String company;
            private String email;
            private String qp;

            public thecontroller() {
                this.qp = ApexPages.currentPage().getParameters().get('qp');
            }

            public String getFirstName() {
                  return this.firstName;
            }

            public void setFirstName(String firstName) {
                  this.firstName = firstName;
            }

            public String getLastName() {
                  return this.lastName;
            }

            public void setLastName(String lastName) {
                  this.lastName = lastName;
            }

            public String getCompany() {
                  return this.company;
            }

            public void setCompany(String company) {
                  this.company = company;
            }

            public String getEmail() {
                  return this.email;
            }

            public void setEmail(String email) {
                  this.email = email;
            }

            public PageReference save() {
                PageReference p = null;
                
                if (this.qp == null || !'yyyy'.equals(this.qp)) {
                    p = Page.failure;
                    p.getParameters().put('error', 'noParam');
                } else {
                    try {
                        Lead newlead = new Lead(LastName=this.lastName, 
                                                FirstName=this.firstName, 
                                                Company=this.company, 
                                                Email=this.email);
                        insert newlead;
                    } catch (Exception e) {
                        p = Page.failure;
                        p.getParameters().put('error', 'noInsert');
                    }
                }
                
                if (p == null) {
                    p = Page.success;
                }
                
                p.setRedirect(true);
                return p;
            }
 }

The controller calls two additional pages: a success page and a failure page. The text of those pages is not important for this example. They merely have to exist.

Vf page

The following markup uses the controller above:

 

   
      
         
Test page for adding leads

         
This is a test page for adding leads.

         
First name: 

         
Last name: 

         
Company: 

         
Email address: 

         
      
   

Test Class

The following class tests the controller:

 
@isTest
public class thecontrollerTests {

    public static testMethod void testMyController() {
        PageReference pageRef = Page.success;
        Test.setCurrentPage(pageRef);
      
        thecontroller controller = new thecontroller();
        String nextPage = controller.save().getUrl();

        // Verify that page fails without parameters
        System.assertEquals('/apex/failure?error=noParam', nextPage);

        // Add parameters to page URL
        ApexPages.currentPage().getParameters().put('qp', 'yyyy');
      
        // Instantiate a new controller with all parameters in the page
        controller = new thecontroller(); 
        controller.setLastName('lastname');
        controller.setFirstName('firstname');
        controller.setCompany('acme');
        controller.setEmail('firstlast@acme.com');
        nextPage = controller.save().getUrl();

        // Verify that the success page displays
        System.assertEquals('/apex/success', nextPage);
        Lead[] leads = [select id, email from lead where Company = 'acme'];
        System.assertEquals('firstlast@acme.com', leads[0].email);
    }
}