i have a trigger that im trying to create a test for and not sure why the coverage is always 0%.

my trigger is

trigger InvalidEmailContactTrigger on Contact (before update)
{
    private String emailissue {get; set;}
    if(Trigger.isBefore)
    {
        emailissue = null;
        for(Contact contact : trigger.old)
        { 
            emailissue = contact.itracmedia__Email_Issue__c;
        }
        
        for(Contact contact : trigger.new)
        {            
            if(contact.itracmedia__Email_Issue__c == null && emailissue != null)
            {             
                EmailIssueRemover.removeEmailIssue(contact.id, emailissue);
            } 
        }
    }
}

 and my test code is

@isTest
private class TestInvalidEmailContactTrigger
{
    public static testmethod void testInvalidEmailContactTrigger()
    {                       
        //Insert a new instance of Contact Object with test values 
        Contact c = new Contact(LastName = 'Test');
        c.itracmedia__Email_Issue__c = 'TestIssue';
        insert c;
        c.itracmedia__Email_Issue__c = null;
        update c;
    }
}

 Can someone help me with getting this test to run successfully.

thanks,

NR