Here is a design pattern for unit tests that I have implemented in Eclipse as a template. The testSetupData() method validates that your @testsetup data is working correctly, and helps to mitigate the risk of changes to workflow, process, and validation in your Org

myUnitTestTemplate.cls

/**
 * This class contains unit tests for validating the behavior of Apex classes
 * and triggers.
 *
 * Unit tests are class methods that verify whether a particular piece
 * of code is working properly. Unit test methods take no arguments,
 * commit no data to the database, and are flagged with the testMethod
 * keyword in the method definition.
 *
 * All test methods in an organization are executed whenever Apex code is deployed
 * to a production organization to confirm correctness, ensure code
 * coverage, and prevent regressions. All Apex classes are
 * required to have at least 75% code coverage in order to be deployed
 * to a production organization. In addition, all triggers must have some code coverage.
 * 
 * The @isTest class annotation indicates this class only contains test
 * methods. Classes defined with the @isTest annotation do not count against
 * the organization size limit for all Apex scripts.
 *
 * See the Apex Language Reference for more information about Testing and Code Coverage.
 */
@isTest
private class ${class_name} {
//setup testClass variables here. For example:
//RecordType Ids
/*private static final Id Customer_RECORD_TYPE_ID = Schema.SObjectType.Account.getRecordTypeInfosByName().get('Customer').getRecordTypeId();*/
//A common Loop Counter for bulikification purposes
/*private static final integer MAX_LOOP_COUNTER = 200;*/
	
	@testSetup static void setupTestData(){
		//setup common test data here
		${cursor}
	}
	
	static testMethod void testSetupData(){
		//use this method to validate that you have test data setup correctly
		//this will protect you from changes to workflow, process, and validation that break your test code!
	}
	
	static testMethod void myUnitTest() {
		// TO DO: implement unit test AFTER you have your test data all setup and verified as OK
	}
}