Reapply "Accident counter"

This reverts commit 9d5615cb9d.

examples/accident-counter/src/counter.test.jsx

@@ -1,34 +1,82 @@
-import { render, screen } from '@testing-library/react';
+import { render, screen, act } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 
 import { Counter } from './counter';
 
 import '@testing-library/jest-dom/vitest';
 
-describe.todo('Counter ', () => {
-  beforeEach(() => {
+describe('Counter ', () => {
+  it('renders with an initial count of 0', () => {
     render(<Counter />);
+    const counter = screen.getByTestId('counter-count');
+    expect(counter).toHaveTextContent('0');
   });
 
-  it('renders with an initial count of 0');
+  it('disables the "Decrement" and "Reset" buttons when the count is 0', () => {
+    render(<Counter />);
+    const decrementButton = screen.getByRole('button', { name: /decrement/i });
+    const resetButton = screen.getByRole('button', { name: /reset/i });
 
-  it('disables the "Decrement" and "Reset" buttons when the count is 0');
+    expect(decrementButton).toBeDisabled();
+    expect(resetButton).toBeDisabled();
+  });
 
-  it.todo('displays "days" when the count is 0', () => {});
+  it('displays "days" when the count is 0', () => {
+    render(<Counter />);
+    const unit = screen.getByTestId('counter-unit');
+    expect(unit).toHaveTextContent('days');
+  });
 
-  it.todo(
-    'increments the count when the "Increment" button is clicked',
-    async () => {},
-  );
+  it('increments the count when the "Increment" button is clicked', async () => {
+    render(<Counter />);
+    const incrementButton = screen.getByRole('button', { name: /increment/i });
+    const counter = screen.getByTestId('counter-count');
 
-  it.todo('displays "day" when the count is 1', async () => {});
+    await act(async () => {
+      await userEvent.click(incrementButton);
+    });
 
-  it.todo(
-    'decrements the count when the "Decrement" button is clicked',
-    async () => {},
-  );
+    expect(counter).toHaveTextContent('1');
+  });
 
-  it.todo('does not allow decrementing below 0', async () => {});
+  it('displays "day" when the count is 1', async () => {
+    render(<Counter />);
+    const incrementButton = screen.getByRole('button', { name: /increment/i });
+    const unit = screen.getByTestId('counter-unit');
+
+    await act(async () => {
+      await userEvent.click(incrementButton);
+    });
+
+    expect(unit).toHaveTextContent('day');
+  });
+
+  it('decrements the count when the "Decrement" button is clicked', async () => {
+    render(<Counter initialCount={1} />);
+    const decrementButton = screen.getByRole('button', { name: /decrement/i });
+    const count = screen.getByTestId('counter-count');
+
+    expect(decrementButton).not.toBeDisabled();
+
+    await act(async () => {
+      await userEvent.click(decrementButton);
+    });
+
+    expect(count).toHaveTextContent('0');
+    expect(decrementButton).toBeDisabled();
+  });
+
+  it('does not allow decrementing below 0', async () => {
+    render(<Counter />);
+    const decrementButton = screen.getByRole('button', { name: /decrement/i });
+    const count = screen.getByTestId('counter-count');
+
+    await act(async () => {
+      await userEvent.click(decrementButton);
+    });
+
+    expect(count).toHaveTextContent('0');
+  });
 
   it.todo(
     'resets the count when the "Reset" button is clicked',
@@ -40,5 +88,14 @@ describe.todo('Counter ', () => {
     () => {},
   );
 
-  it.todo('updates the document title based on the count', async () => {});
+  it('updates the document title based on the count', async () => {
+    const { getByRole } = render(<Counter />);
+    const incrementButton = getByRole('button', { name: /increment/i });
+
+    await act(async () => {
+      await userEvent.click(incrementButton);
+    });
+
+    expect(document.title).toEqual(expect.stringContaining('1 day'));
+  });
 });

examples/accident-counter/src/counter.tsx

@@ -2,8 +2,8 @@ import React from 'react';
 import { useReducer, useEffect } from 'react';
 import { reducer } from './reducer';
 
-export const Counter = () => {
-  const [state, dispatch] = useReducer(reducer, { count: 0 });
+export const Counter = ({ initialCount = 0 }) => {
+  const [state, dispatch] = useReducer(reducer, { count: initialCount });
   const unit = state.count === 1 ? 'day' : 'days';
 
   useEffect(() => {

examples/accident-counter/tests/counter.spec.js

@@ -1,2 +0,0 @@
-import { test, expect } from '@playwright/test';
-import { createServer } from 'vite';