Mock populate when called directly

[pnts-se]

Thank you for a very good library!

I'm able to mock populate() when called in a chain like so:

find()
      .sort({ createdAt: -1 })
      .limit(5)
      .populate("foreignKey");

I'm not able to mock populate() when called directly, e.g:

const doc = new MyModel({
      content: content,
      foreignKey: foreignKey
    });
await doc.save();
await doc.populate("foreignKey");

I get:
TypeError: Cannot read properties of null (reading 'populate')