Mastering State Management with Angular and NgRx/

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Testing Reducers

Testing Reducers

Learn how to unit test the NgRx reducers.

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Introduction

In the products module of our application, we have defined three actions. We handled those actions in the src/app/products/state/products.reducers.ts file with the productsReducer.

  import { createAction, props } from "@ngrx/store";
  import { Product } from "src/app/app.interfaces";
  
  export const getProductsAction = createAction(
    '[Products] Get Products',
    props<{ products: Product[] }>()
  )
  
  export const loadProductsAction = createAction(
    '[Products] Load Products'
  )
  
  export const getErrorAction = createAction(
    '[Products] Load Products Error'
  )
Actions defined in the products module

In this lesson, let’s write a test case to verify if our productsReducer is properly handling the getProductsAction().

Unit testing the NgRx reducers

We can unit test the NgRx reducers by following the steps below.

Creating a spec file

Inside the src/app/products/state folder, let’s create a new file named the products.reducers.spec.ts file. Angular will not run this test file unless we add the spec extension.

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Snapshot of the folder structure of our project
Snapshot of the folder structure of our project

Defining the test suite

Let’s define a ...

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