Design simulation

[mhchia]

What is wrong?

Currently, we only have the simulation of floodsub/gossipsub by jannikluhn. We should have one for the sharding-p2p layer.

How can it be fixed?

The simulation should be able to be done by

• Mock the network component of host.Host with our self-defined Swarm(Network layer). This can be done by replacing them with go channels.
  • Mock components are available in https://github.com/libp2p/go-libp2p/tree/master/p2p/net/mock
    • Example usage: https://github.com/libp2p/go-libp2p-kad-dht/blob/master/ext_test.go#L25
• Spin up all Node instances in one process
• Simulate the network according to the testing spec Design testing spec #24

The best situation is we should be able to switch to simulation mode by modifying as little code as possible

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Edited: Added the link to mock components and example usages.