title: FIELD_CUSTOM_VALIDATION_EXCEPTION
body: <p>I am writing a test class for a trigger. But i am not able to run it properly it only contain 68%. 
  The error is</p>
  
  <pre><code>System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, This part is not forecastable. 
  
  @isTest
  private class TestTriggers
  {
     static testMethod void testService()
     {        
     //Insert part    
      list&lt;Opportunity&gt; Opportunity = new list&lt;Opportunity&gt;();
      Opportunity = [Select id from Opportunity];
      list&lt;Product2&gt; Product = new list&lt;Product2&gt;();
      Product = [Select id from Product2];
      Part__c p = new Part__c(Stage__c = 'idea',Product__c=Product[0].id,Opportunity__c=Opportunity[0].id);
      insert p;
  
     //Update part
      list&lt;part__c&gt; partlist = new list&lt;part__c&gt;();
      partlist =  [Select Stage__c from part__c where Stage__c = 'idea'];
      partlist[0].Stage__c = 'update';
      update partlist;/* */
     }
  }
  </code></pre>
  
  <p>thanks
  Anuraj</p>