Let's say that I have a project where most of the codebase is already covered with Unit Tests (using mocks). How many Integration Tests should I write then? The entire codebase is already covered with unit tests, so how much of the codebase should I cover again with integration tests? 5%? 100%?
I know that numbers always depend on a situation, so here is the stack that I use: I work on the web app using React, Node.js, Typescript + React Native for mobile. The product is not related to anything life-important (it's not a military, health-related project).