Value of field not getting updated in test class

Question

trigger OpportunityTrigger on Opportunity (before insert) {

     for(Opportunity thisOpportunity : Trigger.New) {

     thisOpportunity.New_Value__c ='Actual Trigger Value';
    }

}

This is my test class

@isTest private class OpportunityTriggerHandler_Test {

    @isTest static void test_OpportunityTriggerHandler() {

        Contact ordwayContact =  New Contact();
        ordwayContact.LastName = 'abjsb';
        ordwayContact.MailingStreet = 'Indore';
        insert ordwayContact;
        Test.startTest();
          Opportunity testOpportunity = new Opportunity(
            StageName = 'Prospecting',
            CloseDate = system.today(),
            BillingContact__c   = ordwayContact.Id,
            Name = 'Test Opportunity Triggers'
        );
        insert testOpportunity;

        system.debug('ordwayOpportunity'+testOpportunity.New_Value__c);
       Test.stopTest();

    }

I am not getting the thisOpportunity.New_Value__c in my test class. When I insert the record through UI I am avail to see this value but when I do this through test class not getting the value in the test class

Answer 1

You have to query back the opportunity in order to see the value of the field. Since the value you are showing on the debug shows the value contained in the variable testOpportunity and not the value of the opportunity stored in memory(which was modified by the trigger).

add a line after the update to update the value of the variable with the value stored in memory.

testOpportunity = [SELECT id , New_Value__c FROM Opportunity WHERE id =: testOpportunity.id];

And it should show the correct value.

Bonus1: Anyway I suggest you aswell to change your System.debug to a System.assert since now your test is not making any testing. By using assert you make sure that the test is accomplishing what you intent to.

Something like

System.assertEquals('Actual Trigger Value',testOpportunity.New_value__c);

Bonus 2:

Since hardcoding that string is not the most clean option i would suggest aswell to move that value to a constant on your trigger and either make it public or private with @testvisible. And then reference it on the assert.