test(transport): high-traffic RPC

Problem:
In
vscode-neovim/vscode-neovim#2184 (comment)
it was reported that "Github Copilot Chat opens MANY buffers while
writing code, and that somehow breaks the vscode-neovim extension".

Solution:
- Add test coverage for high amounts of RPC traffic.
- TODO: this doesn't cover complex scenarios such as a looping
  `OptionSet` handler.

packages/neovim/src/api/Base.ts

@@ -118,6 +118,7 @@ export class BaseApi extends EventEmitter {
     });
   }
 
+  /** Sends a request to Nvim (the peer). */
   request(name: string, args: any[] = []): Promise<any> {
     return this.asyncRequest(name, args);
   }

packages/neovim/src/api/client.ts

@@ -63,6 +63,7 @@ export class NeovimClient extends Neovim {
     return this.attachedBuffers.has(key);
   }
 
+  /** Handles incoming request (from the peer). */
   handleRequest(
     method: string,
     args: VimValue[],
@@ -85,6 +86,7 @@ export class NeovimClient extends Neovim {
     }
   }
 
+  /** Publishes to (local) subscribers of this `EventEmitter`. */
   emitNotification(method: string, args: any[]) {
     if (method.endsWith('_event')) {
       if (!method.startsWith('nvim_buf_')) {
@@ -114,6 +116,7 @@ export class NeovimClient extends Neovim {
     }
   }
 
+  /** Handles incoming notification (from the peer). */
   handleNotification(method: string, args: VimValue[], ...restArgs: any[]) {
     this.logger.info('handleNotification: %s', method);
     // If neovim API is not generated yet then queue up requests

packages/neovim/src/attach/attach.test.ts

@@ -7,16 +7,21 @@ import { NeovimClient } from '../api/client';
 describe('Nvim API', () => {
   let proc: ReturnType<typeof testUtil.startNvim>[0];
   let nvim: ReturnType<typeof testUtil.startNvim>[1];
+  /** Incoming requests (from Nvim). */
   let requests: { method: string; args: number[] }[];
+  /** Incoming notifications (from Nvim). */
   let notifications: { method: string; args: number[] }[];
 
   beforeAll(async () => {
     [proc, nvim] = testUtil.startNvim();
 
+    // Incoming requests (from Nvim).
     nvim.on('request', (method, args, resp) => {
       requests.push({ method, args });
       resp.send(`received ${method}(${args})`);
     });
+
+    // Incoming notifications (from Nvim).
     nvim.on('notification', (method, args) => {
       notifications.push({ method, args });
     });
@@ -95,6 +100,25 @@ describe('Nvim API', () => {
     testUtil.stopNvim(nvim2);
   });
 
+  it('very high traffic RPC', async () => {
+    let request_count = 0;
+    const old_request = nvim.request;
+    nvim.request = function (this: any, name: string, args: any[] = []): Promise<any> {
+      request_count += 1;
+      return old_request.call(this, name, args);
+    };
+
+    for (let i = 0; i < 999; i++) {
+      nvim.command('edit test-node-client.lua')
+      nvim.command('bwipeout!')
+    }
+
+    expect(request_count).toEqual(999 * 2);
+
+    // Still alive?
+    expect(await nvim.eval('1+1')).toEqual(2);
+  });
+
   it('can send requests and receive response', async () => {
     const result = await nvim.eval('{"k1": "v1", "k2": 2}');
     expect(result).toEqual({ k1: 'v1', k2: 2 });
@@ -143,7 +167,7 @@ describe('Nvim API', () => {
       end: -1,
       strictIndexing: true,
     });
-    expect(lines).toEqual([]);
+    expect(lines).toEqual(['']);
 
     buf.setLines(['line1', 'line2'], { start: 0, end: 1 });
     const newLines = await buf.getLines({