Integration Tests

• Add a new shard_id.cpp test extension that propagates shardId from AstNode to LogicalStage through its bind() implementation (see example above).
• For the tests below, it’s necessary to have a version that executes on the router and one that executes on the shard.

• Add an integration test that uses shard_id.cpp in a pipeline:
• When in a standalone environment, shardId should be empty.
• When in a sharded environment on the shard, shardId should exist and be correct.

When in a sharded environment on the router, shardId should be empty.

Extension Implementation Example

class ShardIdAstNode : public sdk::AggStageAstNode {
    // ...
    std::unique_ptr<sdk::LogicalAggStage> bind(
        const ::MongoExtensionCatalogContext& catalogContext) const override {
        std::string shardId(extension::byteViewAsStringView(catalogContext.shardId));
        return std::make_unique<ShardIdLogicalStage>(getName(),
                                          std::move(shardId));
    }
    // ...
};