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 code. I might for example paste ten lines of code in and say “this does X”, which is normally all the context needed for it to say “I see. It’s doing X because that function has this behaviour. To make it do Y you nee to do this code […]”.

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 using this tool… note I’ve been doing work example like this example for about two decades so I was fairly productive before).

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)
    );
});