Move store test file to /store folder

store/mutations.spec.js

@@ -0,0 +1,9 @@
+import { state, mutations } from "@/store";
+import mockFilms from "@/test/fake-films.json";
+
+describe("Vuex mutations.", () => {
+  it("tests setFilms mutation.", () => {
+    mutations.setFilms(state, mockFilms);
+    expect(state.films[0].id).toBe(mockFilms[0].id);
+  });
+});