neovim: catch neovim failed tests on CI from nvim exit code

[saidelike]

Atm we detect success or failure for the tests on CI by parsing the log file and searching for the line ==== TESTS FINISHED: code:. It would be more bullet proof to actually rely on the nvim exit code. See commented code below for ideas to implement it.

//packages\test-harness\src\launchNeovimAndRunTests.ts
    tailTest.on("line", function (data: string) {
      console.log(`neovim test: ${data}`);
      if (data.includes("==== TESTS FINISHED:")) {
        done = true;
        console.log(`done: ${done}`);
        const found = data.match(/.*==== TESTS FINISHED: code: (\d+).*/);
        console.log(`found: ${found}`);
        if (found !== null) {
          code = parseInt(found[1]);
          console.log(`code: ${code}`);
        }
      }

//packages\test-harness\src\runners\extensionTestsNeovim.ts
export async function run(plugin: NvimPlugin): Promise<void> {
  /**
   * We need to pass the neovim client to the tests that are executed through mocha,
   * so we add it to the global object.
   * @see https://github.com/mochajs/mocha/issues/3780#issuecomment-583064196
   * @see https://stackoverflow.com/questions/69427050/how-to-extend-globalthis-global-type
   */
  const client = plugin.nvim as NeovimClient;
  (global as any).additionalParameters = {
    client: client,
  };
  let code = 0;
  try {
    await runAllTests(TestType.neovim, TestType.unit);
    console.log(`==== TESTS FINISHED: code: ${code}`);
    // console.log(`index.ts: killing neovim with q!`);
    // await client.command(":q!");
  } catch (error) {
    console.log(`==== TESTS ERROR:`);
    console.error(error);
    code = 1;
    console.log(`==== TESTS FINISHED: code: ${code}`);
    // https://stackoverflow.com/questions/11828270/how-do-i-exit-vim
    // console.log(`index.ts: killing neovim with cq!`);
    // await client.command(":cq!");
  }
  // XXX: launchNeovimAndRunTests.ts will catch neovim exit code on CI

  // console.log(`index.ts: killing neovim with code ${code}`);
}