Bring randomness in Emulator on par with `testnet` & `mainnet`

[m-Peter]

Improve Randomness in Emulator

Grant category

Please select one:

• [x] Open source maintenance
• [x] Developer tools / services
• [ ] Educational material

Description

The recent introduction of on-chain native randomness brought excitement to the community builders. This feature is available for usage in testnet & mainnet environments.

Problem statement

This feature, however, cannot be utilized from the Flow Emulator, as it does not have the notion of a system chunk transaction on every block commit. Hence, the RandomBeaconHistory contract does not record anything.

Proposed solution

The RandomBeaconHistory contract available on the emulator's service account needs a couple changes to be fully functional and mimic the behavior from testnet/mainnet environments.

• We need to add the option fvm.WithRandomSourceHistoryCallAllowed(true) when configuring Emulator's blockchain
• Up until now, the emulator did not have the notion of a system chunk transaction for every committed block. We need to add one, at least with a call on RandomBeaconHistory's heartbeat.

Impact

The Flow Emulator has evolved into a swiss army knife, which can be used for local development when building a dApp, or as a 3rd party library in all sorts of tools (including the Cadence testing framework). Having the randomness feature be on par with testnet & mainnet, will greatly enhance the DevEx.

Milestones and funding

Milestone	Deliverables	Timeline	Risks	USD proposal
1 - Implementation	Merge https://github.com/onflow/flow-emulator/pull/511	2 weeks	-	3500

Total funding proposed: 3500 $

Team

Name	Role	Bio	Contact
Ardit Marku	Back-end Engineer	A seasoned back-end engineer with a focus on problem solving and designing robust software systems. Over 9 years of experience building high-traffic search engines, marketplaces, exchanges and in-house analytics solutions. Led cross-functional teams to deliver both web and mobile apps, participating in all steps of the software development lifecycle. Open source lover and advocate.	markoupetr@gmail.com m_peter

[m-Peter]

The relevant PR (https://github.com/onflow/flow-emulator/pull/511) from Milestone 1 has been merged, so I think we can mark this as completed :pray:

[franklywatson]

Great work thanks!