Testing large vue apps?

Question

Software testing

How many articles I read everywhere talking about the need for tests, but I could not find a single article describing how to test large applications?
That is, we have an application that consists of a dozen different components, vuex, a bunch of API requests. How do I understand what exactly I need to cover with tests? After all, according to the logic, it is necessary to cover each piece in order to be 100% sure in this code?
Can anyone suggest articles on this topic and in general on the topic of testing vue applications?

Answer 1

But how to test large applications?

Yes, exactly the same.

How do I understand what exactly I need to cover with tests?

This question is solved by the test analysis.
How to learn as much as possible about the state of the application in the minimum number of runs, and so that it brings as much benefit as possible.

After all, logically, it is necessary to cover each piece in order to be 100% sure of this code?

Yes, but full coverage is very expensive and often not justified.
By the fact, if the application is large, but there are no tests:
1. We cover the most critical and important, without which you simply cannot live if it breaks.
2. Covers where a lot of changes happen and there is a chance of accidental breakage.
3. We cover everything new as part of the feature implementation.
4. Unit tests still make sense to cover all sorts of common components that are used stupidly everywhere.
Everything is old, stable, isolated, it is believed that there is not much point in testing, because it has been tested by users for a long time up and down.
But over time, it is better to increase the percentage of coverage - for example, when there are no particularly other tasks or there is extra time.
And vue has nothing to do with it.