Actions mapped to namespaced modules pass unexpected explicit undefined payload to store.dispatch

[markrian]

Version

3.1.1

Reproduction link

https://codepen.io/markrian/pen/vqeGZZ?editors=0010

Steps to reproduce

1. Open https://codepen.io/markrian/pen/vqeGZZ?editors=0010
2. Open the browser's console
3. Observe the differing logged arguments passed to store.dispatch depending on whether it's a root-mapped action or a namespace-mapped action ([ "foo" ] and [ "childModule/foo", undefined ] respectively - note the extra undefined argument in the second case; the different action name is of course expected)

Note that this only really applies in a testing scenario, where the test spies on store.dispatch to ensure the component dispatches the expected actions.

What is expected?

store.dispatch receives exactly the same arguments regardless of whether the actions are namespace-mapped or not.

What is actually happening?

store.dispatch receives a payload argument of undefined for namespace-mapped actions.

---

I encountered this when refactoring a store into a namespaced module, and found that my expectations needed to change: that store.dispatch received an extra undefined argument.

I'm not sure if this should be considered a bug in Vuex, or in my testing approach of spying on store.dispatch 🤷‍♂️

[ghost]

This is happening because of https://github.com/vuejs/vuex/blob/v3.1.1/src/store.js#L360 (explicitly passing payload to dispatch even if undefined). A simple (but admittedly not elegant) fix would be

-  return store.dispatch(type, payload)
+  return payload ? store.dispatch(type, payload) : store.dispatch(type)

[ant1m4tt3r]

I can work on this issue. Seems preety simple to implement @gitlab-winnie solution.

[kiaking]

Closing due to it might already fixed. See comment #1676 (comment). Please feel free to open another issue if this is something that we should solve.