Fix aggregate cursor als

[IchirokuXVI]

Summary

Aggregate cursors didn't automatically add session if it was present in AsyncLocalStorage. Also the options weren't the same for exec and cursor so I added a function to make them the same just like in QueryCursor.

Examples

const mongoose = require("mongoose");
mongoose.set("transactionAsyncLocalStorage", true);

mongoose.connect("mongodb://127.0.0.1:27017/cursortest");

const test = async () => {
  await mongoose.connection.transaction(async (session) => {
    const TestModel = mongoose.model(
      "Test",
      new mongoose.Schema({ name: String })
    );

    mongoose.set("debug", true);
    await TestModel.aggregate([{ $match: {} }]);
    const cursor1 = TestModel.aggregate([{ $match: {} }]).cursor();
    const cursor2 = TestModel.aggregate([{ $match: {} }])
      .session(session)
      .cursor();

    await cursor1.next();
    await cursor2.next();
    mongoose.set("debug", false);

    /*
        From the debug logs:
            Mongoose: TestModel.aggregate([ { '$match': {} } ], { session: ClientSession("bb843cfeb01d4ec3ad0373d2b7d3db20") })
            Mongoose: TestModel.aggregate([ { '$match': {} } ], { cursor: {}, session: ClientSession("bb843cfeb01d4ec3ad0373d2b7d3db20")})
            Mongoose: TestModel.aggregate([ { '$match': {} } ], { session: ClientSession("bb843cfeb01d4ec3ad0373d2b7d3db20"), cursor: {}})

        Before the fix the first cursor didn't have a session but aggregate and second cursor had a session.
    */
  });
};

test()
  .then(() => console.log("Finished"))
  .catch((error) => console.error(error))
  .finally(() => process.exit(0));

[vkarpov15]

I had a couple of minor style suggestions, but looks good overall.

[vkarpov15]

clone() shouldn't be necessary here, would be ideal to avoid cloning for performance purposes

[IchirokuXVI]

The previous implementation also used clone(), so I retained it to ensure no existing functionality was unintentionally affected. However, I agree that removing clone() could improve performance. If it’s deemed unnecessary, I suggest calling the function directly in the constructor to initialize the options instead.

[vkarpov15]

Similar to previous comments, is there any need to set c.options at all? Could just call aggregate(agg._pipeline, agg.optionsForExec())

[IchirokuXVI]

In QueryCursor, options is also set to a new object, so I followed the same approach here.
That said, QueryCursor uses the options object for some checks while AggregateCursor only uses it in _init, so it might make sense to remove it from AggregateCursor for now.

[IchirokuXVI]

Removed the cloning in _optionsForExec and also sest the options before creating AggregationCursor in Aggregate.cursor(). Passed all tests with npm test.