Add getConnectionParameters() method to WebSocket client

[awarus]

Add a new getConnectionParameters() method to NeonClient that exposes PostgreSQL connection parameters sent by the server during the connection lifecycle.

Added test coverage in tests/cli/ws.test.ts

[jawj]

On the implementation side, I wonder if this should be a getConnectionParameters() method, or simply a connectionParameters property? (And if additional work were ever needed at call time, which currently it is not, that property could always be changed to a getter).

But to step back a minute, I'm curious about the specific reason for adding this functionality to the driver itself. It's more or less a one-liner for users to add their own parameterStatus listener, as this implementation shows. So is this not just one more thing to maintain (and a divergence from the underlying node-postgres driver)?

[awarus]

I am fine with any option that lets us parsing custom ParameterStatus. If it's better to have as field, I am fine with that - I have zero experience in ts :)

My main motivation behind that is that we use ParameterStatus messages for debugging purposes of the serverless driver connections. It helps us measuring latencies and provide additional debug data.
I think if this change become a burden with high divergence from node-postgres we can always decide to drop it. Reason to have it for now - easy to use vanilla serverless driver without any additional tweaks and because it's harmless

[jawj]

I feel like I'm being difficult here — sorry! But I think the change is only mostly harmless. It means every Client created by everyone everywhere will suck up a few hundred extra bytes to store the connection parameters, even though 99%+ of the time these will never be used.

Can we not just drop in a single-file subclass anywhere we need this? Namely:

import { Client, Pool, Connection } from '@neondatabase/serverless';

// reassure TypeScript that `connection` exists on Client instances
export interface ConnParamClient {
  connection: Connection;
}

// a Client subclass that saves parameterStatus key/values
export class ConnParamClient extends Client {
  connectionParameters: Map<string, string> = new Map();
  constructor(...args: any[]) {
    super(...args);
    this.connection.on('parameterStatus', (msg: any) =>
      this.connectionParameters.set(msg.parameterName, msg.parameterValue));
  }
}

// a Pool subclass for ConnParamClients
export class ConnParamPool extends Pool {
  Client = ConnParamClient;
}

[awarus]

Sorry, didin't get it with the first comment, now I see the issue. Yes, I agree, that would be much better! Will fix this now

[awarus]

Handle this in a proper way in another PR. Thanks again :)