Do you have any prefer ways to test a function that use many promises? about ama

[gaearon]

It depends on what behavior you would like to test.

[chentsulin]

When I implement a module something like api middleware in redux real world example, I found I don't really know how to well test it. Then I split it into middleware, api utils, schemas three files and try to follow single responsibility principle.

Maybe I Just want to avoid introducing some stupid bugs when I modified some code. I usually mock third party libraries in unit tests and then test they have been called correctly, but it seems cumbersome when a lot of .then call. Hope to hear some your advice or your past experience here.

[gaearon]

I'd just mock fetch and verify that different API responses handled in different order produce a state that makes sense. If I needed to test something more specific, I'd split the function and test its parts separately.