Notes
- Do not put (seeAllData = true) in test class otherwise, use it for exceptional cases.
- Use @isTest at the Top for all the test classes.
- Test in bulk: Test to see if your code can run on 200 records at once.
Test class must start with @isTest annotation. Focus 90+ : To deploy to production at least 75% code coverage is required. But always try to focus on 90%+. We should not focus on the percentage of code coverage, We should make sure that every use case should covered including positive, negative,bulk and single record.