ApexPages.AddMessage low coverage in Test Class and Failed insert

Question

I am having 2 issues with my Test Class. Coverage of 3 lines which I have comented on in the code below. And the insert is failing saying that the account a.id is null. The controller is used in a Visualforce page.
Do I need to create another test Account in the Save?

public with sharing class MerchandisingController {

public Merchandising__c merch{get;set;}
public string message {get;set;} <u><b> ----no coverage</b></u>

public MerchandisingController (ApexPages.StandardController controller) 
{
    merch = new Merchandising__c();
    merch.Account__c= ApexPages.CurrentPage().getparameters().get('someId');
}

  public void save() {
  insert merch; 
  message = 'Record Created Successfully.Please add pictures of the disply to the Account. Thank you!'; ----no coverage
  ApexPages.AddMessage(new ApexPages.Message(ApexPages.Severity.CONFIRM,message )); ----no coverage
}  
}

Test Class

@isTest
private class TestMerchandiseController {
static testmethod void testM(){

Test.StartTest(); 

    Account a = new Account();
    a.Name  = 'Test Account';
    insert a;

    ApexPages.StandardController sc = new ApexPages.StandardController(a);
    MerchandisingController testMerch = new MerchandisingController (sc);

   PageReference pageRef = Page.Merchandising_V2; 
   pageRef.getParameters().put('id',a.Id);
   Test.setCurrentPage(pageRef);

   testMerch.save();
   Merchandising__c m = new Merchandising__c();
   m.Account__c= a.Id;
   m.Merchandise__c= 'Trex Rod Rail Display';
   m.Merchandise_Category__c= 'Full Size(6ft)';
   m.Merchandise_SubCategory__c = 'Black/Black';
   insert m ; 

   System.assert(ApexPages.hasMessages(ApexPages.SEVERITY.CONFIRM));
   Test.StopTest();

}   
}

Answer 1

You main controller is already instantiating Mechandising__C , you dont have to do that in you test class. Your test class would be clean.

@isTest
private class TestMerchandiseController {
    static testmethod void testM(){



        Account a = new Account();
        a.Name  = 'Test Account';
        insert a;

        ApexPages.StandardController sc = new ApexPages.StandardController(a);
        MerchandisingController testMerch = new MerchandisingController (sc);

        PageReference pageRef = Page.Merchandising_V2; 
        pageRef.getParameters().put('id',a.Id);
        Test.setCurrentPage(pageRef);


        testMerch.merch.Merchandise__c= 'Trex Rod Rail Display';
        testMerch.merch.Merchandise_Category__c= 'Full Size(6ft)';
        testMerch.merch.Merchandise_SubCategory__c = 'Black/Black';

        Test.StartTest(); 
        testMerch.save(); //Doing DML
        Test.StopTest();


       System.assert(testMerch.merch.ID!=null,'Mechandise was not inserted');
       System.assert(testMerch.merch.Account__c!=a.Id,'Mechandise account does not match with what provided as ID to the controller');


    }   
}

Unit tests are written to test the behaviour, Not the error messages.

That being said, your line insert merch; is giving an error, because you might not have provided a mandatory field or there is an Apex trigger validation or validation which is breaking. Check the test execution debug logs. They will indicate the proper error.

Answer 2

Some reordering need to be done

@isTest
private class TestMerchandiseController {
static testmethod void testM(){

Test.StartTest(); 

    Account a = new Account();
    a.Name  = 'Test Account';
   insert a;
   PageReference pageRef = Page.Merchandising_V2; 
   pageRef.getParameters().put('someId',a.Id);
   Test.setCurrentPage(pageRef);
   ApexPages.StandardController sc = new ApexPages.StandardController(a);
   MerchandisingController testMerch = new MerchandisingController (sc);
   testMerch.save();
   System.assert(ApexPages.hasMessages(ApexPages.SEVERITY.CONFIRM));
   Test.StopTest();

}   
}

public with sharing class MerchandisingController {

public Merchandising__c merch{get;set;}
public string message {get;set;} 

public MerchandisingController (ApexPages.StandardController controller) 
{
    merch = new Merchandising__c();
    merch.Account__c= ApexPages.CurrentPage().getparameters().get('someId');
}

  public void save() {
  insert merch; 
  message = 'Record Created Successfully.Please add pictures of the disply to the Account. Thank you!'; 
  ApexPages.AddMessage(new ApexPages.Message(ApexPages.Severity.CONFIRM,message )); 
}  
}