Delete tests

One of the most important things you can do is move your tests up the abstraction layers and away from unit tests. For lack of a better term, to move to integration tests. End-to-end tests are often too far from the system to easily understand what's wrong when they break, and can overwhelm a development org. Integration tests (or whatever you want to call them) are often the sweet spot: not tied to a particular implementation, able to survive fairly significant system changes, but also easy enough to debug when they break.

https://grugbrain.dev/#grug-on-testing

Integration tests and Unit tests are different tools; and each has their place and purpose. Using one "instead" of the other is a mistake.

Integration tests make unit tests absolutely redundant.

Integration tests are as old as unit tests, and both predate their names. When exactly were unit tests made redundant? I don't see the point of your quip without a trace of actual argument.

I feel like I don't write enough tests, and when I do they're usually integration tests, but some things - algorithms, complex but pure functions, data structures - absolutely deserve their unit tests that can't be reasonably replaced by integration/e2e tests.

Here's the argument backing up my claim.

Unit tests don't matter when you have other types of testing like functional or integration testing that will tell you whether your code has the intended behavior and effect when run.

In the above statement unit tests is also considered as code.

That's where the redundancy comes from.