Function run

test/integration/node-specific/client_close.test.ts:91–118

({
              MongoClient,
              uri,
              expect,
              sleep,
              mongodb,
              getTimerCount
            })

          metadata,
          async function () {
            const run = async function ({
              MongoClient,
              uri,
              expect,
              sleep,
              mongodb,
              getTimerCount
            }) {
              const serverSelectionTimeoutMS = 2222;
              const client = new MongoClient(uri, {
                minPoolSize: 1,
                serverSelectionTimeoutMS,
                readPreference: new mongodb.ReadPreference('secondary', [
                  { something: 'that does not exist' }
                ])
              });
              const insertPromise = client.db('db').collection('collection').insertOne({ x: 1 });

              // don't allow entire server selection timer to elapse to ensure close is called mid-timeout
              await sleep(serverSelectionTimeoutMS / 2);

              expect(getTimerCount()).to.not.equal(0);
              await client.close();
              expect(getTimerCount()).to.equal(0);

              const err = await insertPromise.catch(e => e);
              expect(err).to.be.instanceOf(mongodb.MongoTopologyClosedError);
            };
            await runScriptAndGetProcessInfo('timer-server-selection', this.configuration, run);
          }
        );