Mastering Vuex: A Step-by-Step Guide to Building and Testing a Vuex Module
As your Vue application grows in complexity, managing state across multiple components becomes a daunting task. This is where Vuex comes in – a state management pattern and library that helps you maintain a centralized state management system. In this article, we’ll explore the world of Vuex by building and testing a Vuex module using TypeScript and Jest.
What is Vuex?
Vuex is a state management library for Vue applications that allows you to manage state in a centralized manner. It consists of four core concepts:
- State: The central hub of your application’s data.
- Getters: Derived state based on the store state.
- Mutations: The only way to change the state.
- Actions: Perform asynchronous operations and commit mutations.
Building a Vuex Module
To demonstrate the power of Vuex, let’s create a simple to-do list application. We’ll create a new module for to-do operations, which will be responsible for fetching and updating the state.
Our module will consist of three files:
mutation-types.ts: Contains all the function names.actions.ts: Responsible for asynchronous operations.index.ts: The module implementation.
Initializing Tests
We’ll use Jest as our testing framework. To initialize the tests, we’ll create a store, attach Vuex to Vue, and register the store.
Testing Actions
In our to-do module, we created a fetchTodos action that fetches data from a REST API and fills the state using mutations. We can mock the REST API using a Jest function and validate whether it’s being called and the state is being updated.
Testing Getters
Getter functions simply return the state object. In our example, we have a completedTodos getter that returns the completed to-do items.
Testing Mutations
Mutations are the only way to change the state. We can test the ON_FETCH_TODOS_SUCCESS mutation by sending mock to-do tasks and validating whether the state is modified.
By following these steps, you’ll be well on your way to mastering Vuex and building robust, scalable Vue applications. With Vuex’s centralized state management, you can simplify your application and take advantage of Flux-like architecture.
Happy coding!