Sample Code: public static User createTestempUser(Id roleId, Id profID, String fName, String lName) { String orgId = UserInfo.getOrganizationId(); String dateString = String.valueof(Datetime.now()).replace(' ','').replace(':','').replace('-',''); Integer randomInt = Integer.valueOf(math.rint(math.random()*1000000)); String uniqueName = orgId + dateString + randomInt; User tempUser = new User( FirstName = fName, LastName = lName, email = uniqueName + '@test' + orgId + '.org', Username = uniqueName + '@test' + orgId + '.org', EmailEncodingKey = 'ISO-8859-1', Alias = uniqueName.substring(18, 23), TimeZoneSidKey = 'America/Los_Angeles', LocaleSidKey = 'en_US', LanguageLocaleKey = 'en_US', ProfileId = profId, UserRoleId = roleId ); insert tempUser; return tempUser; }