Not sure how I hadn't encountered this before, I LOVE this pattern.
I find integration tests that exercise actual databases/Elasticsearch/Redis/Varnish etc to be massively more valuable than traditional unit tests. In the past I've gone to pretty deep lengths to do things like spin up a new Elasticsearch index for the duration of a test suite and spin it down again at the end.
It looks like Testcontainers does all of that work for me.
My testing strategy is to have as much of my application's functionality covered by proper end-to-end integration-style tests as possible - think tests that simulate an incoming HTTP request and then run assertions against the response (and increasingly Playwright-powered browser automation tests for anything with heavy JavaScript).
I'll use unit tests sparingly, just for the bits of my code that have very clear input/output pairs that afford unit testing.
I only use mocks for things that I don't have any chance of controlling - calls to external APIs for example, where I can't control if the API provider will be flaky or not.
I find integration tests that exercise actual databases/Elasticsearch/Redis/Varnish etc to be massively more valuable than traditional unit tests. In the past I've gone to pretty deep lengths to do things like spin up a new Elasticsearch index for the duration of a test suite and spin it down again at the end.
It looks like Testcontainers does all of that work for me.
My testing strategy is to have as much of my application's functionality covered by proper end-to-end integration-style tests as possible - think tests that simulate an incoming HTTP request and then run assertions against the response (and increasingly Playwright-powered browser automation tests for anything with heavy JavaScript).
I'll use unit tests sparingly, just for the bits of my code that have very clear input/output pairs that afford unit testing.
I only use mocks for things that I don't have any chance of controlling - calls to external APIs for example, where I can't control if the API provider will be flaky or not.