Testing Redux Logic

Learn to test reducers, selectors, and thunks effectively.

25 min

3 sections

testing

vitest

quality

01. Testing Reducers

Section 1 of 3

Reducers are pure functions and easy to test. Call them with initial state and actions, assert on result.

typescript

import todosReducer from './slice';
import { addTodo } from './slice';

describe('todos reducer', () => {
  it('handles addTodo', () => {
    const initialState = { items: [] };
    const action = addTodo({ text: 'Test' });
    const state = todosReducer(initialState, action);

    expect(state.items).toHaveLength(1);
    expect(state.items[0].text).toBe('Test');
  });
});

Exercise

Test a Reducer

Practice

Write a test for a counter reducer's increment action.

TypeScript Integration

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