So this isn't a real example, it's just something I slapped together now as an example of how I generally use ChatGPT 4.0. In a more realistic scenario, I'd be asking more detailed questions, pasting in my existing code, and asking the AI to write smaller sections (maybe 10 lines of code at a time).

A single chat might run for five or six hours, continuously discussing an individual task I'm working on, and I won't just be asking it to write a bunch code. For example in this case I might spend 10 minutes hashing out the exact contents of the 'Activity' record (or, maybe I already did that a month ago, and I might just paste in an example). I'd also be testing the code as I go and writing some of it myself, occasionally asking questions like 'how do I format a date as 4 Feb 2016' in JavaScript?' or 'this line of code fails with X. Why?'

In those five or six hours, I estimate I'm able to get two or three days of work done (at my level of productivity before I started paying $20/month for ChatGPT+).

I'm also only pasting the code - ChatGPT also explains the code it outputs, and often those explanations are more useful than the actual code.

In JavaScript write a "reserveSeat('A42', 'Adult')" function that sends an ActivityStreams 2.0 activity to (this.apiUrl)/reserve and inform the user if it failed to be reserved

class SeatReservationService {
  constructor(apiUrl) {
    this.apiUrl = apiUrl;
  }

  async reserveSeat(seatNumber, seatType) {
    // Construct an ActivityStreams 2.0 compliant JSON object
    const activity = {
      '@context': 'https://www.w3.org/ns/activitystreams',
      'type': 'Reserve',
      'actor': {
        'type': 'Person',
        'name': 'User'
      },
      'object': {
        'type': 'Seat',
        'id': seatNumber,
        'category': seatType
      }
    };

    try {
      // Send the activity object to the specified API endpoint using an HTTP POST request
      const response = await fetch(`${this.apiUrl}/reserve`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json'
        },
        body: JSON.stringify(activity)
      });

      // Handle the server’s response
      if (response.ok) {
        // If the request was successful, log a success message
        console.log('Seat reserved successfully.');
      } else {
        // If the server responds with a status code other than 2xx, throw an error
        throw new Error('Failed to reserve seat. Server responded with ' + response.status);
      }
    } catch (error) {
      // Inform the user if the reservation failed
      console.error('Failed to reserve seat:', error);
      alert('Failed to reserve the seat. Please try again.');
    }
  }
}

// Usage
const service = new SeatReservationService('https://example.com/api');
service.reserveSeat('A42', 'Adult');

Write a PHP request handler that does $this->reserveSeat('A42'), and checks if it failed with a SeatNotAvailable exception

class SeatNotAvailable extends Exception {
    public function __construct($message = "Seat not available", $code = 0, Exception $previous = null) {
        parent::__construct($message, $code, $previous);
    }
}

class SeatReservationService {

    public function reserveSeat($seatNumber) {
        // Mockup condition that the seat 'A42' is not available
        if ($seatNumber === 'A42') {
            throw new SeatNotAvailable("Seat $seatNumber is not available.");
        }

        // Normally here you'd interact with a database or another kind of storage
        // to actually reserve the seat.
        // ... (reserve seat logic) ...
        
        return true;
    }
}

class SeatReservationController {

    private $service;

    public function __construct() {
        $this->service = new SeatReservationService();
    }

    public function handleRequest() {
        try {
            $this->service->reserveSeat('A42');
            echo "Seat reserved successfully.";
        } catch (SeatNotAvailable $e) {
            echo $e->getMessage();
        }
    }
}

Write a PHPUnit test for SeatReservationController, and a Jest one for SeatReservationService

createMock(SeatReservationService::class);
        $serviceMock->method('reserveSeat')
                    ->willReturn(true);

        $controller = new SeatReservationController($serviceMock);
        $this->expectOutputString("Seat reserved successfully.");
        $controller->handleRequest();
    }

    public function testSeatNotAvailableException() {
        $serviceMock = $this->createMock(SeatReservationService::class);
        $serviceMock->method('reserveSeat')
                    ->will($this->throwException(new SeatNotAvailable()));

        $controller = new SeatReservationController($serviceMock);
        $this->expectOutputString("Seat not available");
        $controller->handleRequest();
    }
}

const SeatReservationService = require('./SeatReservationService'); // Adjust the path as necessary

test('reserves a seat successfully', async () => {
    const service = new SeatReservationService('https://example.com/api');
    global.fetch = jest.fn(() => 
        Promise.resolve({
            ok: true
        })
    );

    await service.reserveSeat('A41', 'Adult');
    expect(fetch).toHaveBeenCalledWith(
        'https://example.com/api/reserve', 
        expect.objectContaining({
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
        })
    );
});

test('fails to reserve a seat', async () => {
    const service = new SeatReservationService('https://example.com/api');
    global.fetch = jest.fn(() => 
        Promise.resolve({
            ok: false,
            status: 400
        })
    );

    global.console = { error: jest.fn(), log: jest.fn() };

    await service.reserveSeat('A42', 'Adult');
    expect(console.error).toHaveBeenCalledWith(
        'Failed to reserve seat:', 
        expect.any(Error)
    );
});