import com.atlassian.jira.component.ComponentAccessor
def issueManager = ComponentAccessor.getIssueManager()
def issueService = ComponentAccessor.getIssueService()
def userManager = ComponentAccessor.getUserManager()
def user = userManager.getUserByName("tbas")
def issue = issueManager.getIssueObject("HW_TEST-64")
def validateAssignResult = issueService.validateAssign(user,
issue.id, issue.reporterId)
issueService.assign(user, validateAssignResult)