Simulation: Params from File

[alexanderbez]

Summary

Simulation should have the ability to execute from a predefined set of parameters. This will allow for more reproducible runs and execution paths. The simulation test will have a top level structure of parameter stores and keys. Given a file, if an given subspace/key exists, it'll be used. Otherwise, it'll generate a pseudo-random one as it does now.

/cc @npinto @rigelrozanski

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[rigelrozanski]

So already we can already simulate from a genesis file (see #3182) which allows us to include custom parameters. However it may also be nice to have something a bit more flexible in code

[alexanderbez]

Correct @rigelrozanski but I'd essentially would like to decouple that. ie. consume params from file and simulating state.

So you can essentially run simulation in three ways:

1. Raw; no params and no genesis inputs (what CI does)
2. Raw w/ Params input; implicitly will not allow genesis as input
3. Raw w/ Genesis input; implicitly will not allow params as input

[npinto]

This is great ;-) cc: @fernand

[rigelrozanski]

@alexanderbez yup that set of options seems good - I'm a bit confused as to what the format of a params file would look like though? (is that not effectively a genesis file? what's different) - if you're referring to a custom param set defined in code then this makes sense to me once again.

[alexanderbez]

Yeah precisely @rigelrozanski. The params file is just a flat JSON file of key/values. Because simulation generates random parameters outside of just modules (e.g. amount of tokens per account), the genesis file won't cut it.