I am getting some strange results with test methods. I have a class that contains several test methods. If I run the test for that class only, some of my System.Assert statements fail. All the failures have to do with a custom picklist field. However if I take just one of the test methods and run it in its own class then the same statements that failed before now pass the System.Assert. I was under the impression that each test method in a class runs independently of all other test methods. My results don't seem to agree with this?

Upon further investigation the problem only happens when I set a custom picklist field to a value not in the picklist. The field is not a restricted picklist. I can see from the debug log that the value I have set in the field (Owner_Assigned__c = Hardware1) is present immediately before the validation rules fire (last line of the insert trigger is a system.debug statement). One of the validation rules references this field and the log shows that this has been set to another value (Owner_Assigned__c=12). This value of 12 is not a real value because in the code that follows the case insert in the test method the system.Assert that fails shows the value as null. Also if I create a validation rule to fire when the value of this field is 12 it never fails.

If I add the test value for this field that I am using to the picklist, all the tests run fine. Note that the test methods are never returning any DML or other exception errors. It is only the system.assert statements that are catching something.

Is there something I am doing incorrectly in my testing that would explain all of this?

Thanks

Dave