No mutation, so please create a new array `newSecureItems` and then `newSecureItems.push({ key: .... value: ....})`

Why did you need to override this method?

Could you abstract this away and make `shim.loadSecureItems` return an array of `{ key: 'foo', value: 'bar' }`?

Please make async

Can be removed.

As this is only used by your code, please remove it from the shim and keep as a private helper method.

Please make these methods async. Keytar might be synchronous, but it's likely that for example a React Native lib would be async, so it needs to work with both.

Should be `await shim.saveSecureItem(....`

The logic is not right here because the `load()` function will exit before your code here has run, which could cause race conditions. I think you should change this to `return shim.loadSecureItems(...` although ideally all this method should be refactored with async/await.

If you refactor the functions as described above you won't need all this duplicated code.

Same comment as above. That function should save a secure item and that's it.

loadSecureItems should only do the absolute minimum related to keychain - it should return an array with the relevant credentials and that's it. There's shouldn't be Setting related code, let alone dispatching actions, in here. That also means refactoring the call in Setting.js

I don't think this tests anything related to this feature, because the test env may or may not have a keychain.

setValue is not async

should be in beforeEach

That's not specific to the keychain feature

`keytar` is installed and always available so no need for a try/catch block

Again no device check in Setting.js. Use the shim

Please don't check for app type here. Instead use lib/shim.js to abstract away differences between platforms. For example create a function in the shim that returns all the secure credentials. On Node/Electron, make it use keytar. On React Native, since it's not implemented, make it return an empty array. Make sure that the logic means that it works both on RN and Node.