Add jest coverage + Test setFruits mutation

src/store/index.js

@@ -4,8 +4,10 @@ import Vuex from "vuex";
 Vue.use(Vuex);
 
 export default new Vuex.Store({
-  state: {},
-  mutations: {},
+  state: {
+    fruits: []
+  },
+  mutations: import("./mutations.js"),
   actions: {},
   modules: {}
 });