small details during development: Incomplete logic Effect on other components DB becomes locked for a long period Cannot think about what will bring great value to the user Testing is an effective approach for various concerns, big and small
Doesn’t know testing other than acceptance testing “Unit test? What is that? Can you eat it?” Misunderstanding of refactoring Starts off prioritizing implementation without any automated testing “We can just refactor it later, right? :D”
error if a required field is empty 2. Display an error if the email address does not contain “@” 3. [Submit] button cannot be clicked if there is an error 4. Email addresses that are already registered cannot be registered 5. Registration is complete when the user clicks the link in the new registration email
targeted concern by effectively using the existing interface and mock. Remake applications protected by the test so that they are even easier to test. Maximize the product’s appeal by testing products high in internal quality.