How can I unit-test a pinia store getters and actions?

[roshmani]

I am new to pinia and vitest , I tried a few things based on the document, i am not sure if it is the right way.

I am trying to test an action in pinia eg:-

loadSettings(){
 return return new Promise((resolve) => {
          getSettings()
         .then((response)=>{
            this.settings=response.data;
             resolve(response.data);
        }).catch((error) => {
              appStore.showError({
                response: error,
                customErrorMessage: "Error!",
              });
            reject(error);
            });
}

// getter

getSettings(){
 /* return this.settings after some manipulations*/
....
 return this.settings;
}

which calls an open-api function (axios call) as follows :

let myStore = null;

  beforeEach(() => {
    setActivePinia(createPinia());
    // create an instance of the data store
    myStore = useMyStore();
    appStore= useAppStore();
  });

  afterEach(() => {
    vi.restoreAllMocks();
  });

test("load settings", async () => {
    const loadSettingsSpy = vi.spyOn(myStore, "loadSettings");

    loadSettingsSpy.mockImplementationOnce(() => settings);

    await myStore.loadSettings();
    expect(loadSettingsSpy).toHaveBeenCalledTimes(1);
  });

This test seems to work. I would like to assert the value in the state (this.settings ) somehow . How can i do that?

I also tried to mock the error for the same action which goes to the catch block.

For that I tried :

test("load settings- error on loading", async () => {
     const loadSettingsSpy = vi.spyOn(myStore, "loadSettings");
     const errorSpy=vi.spyOn(appStore, "showError");

    loadSettingsSpy.mockImplementation(() => new Error("Error"));

    await myStore.loadSettings();
    expect(loadSettingsSpy).toHaveBeenCalledTimes(1);
    expect(errorSpy).toHaveBeenCalledTimes(1);
}

It fails, is there any way i can mock an error from the api call ? and also what is the right way to test the getters and actions ?

TIA