Merge PR cosmos#4435: Simulation: Params from File

* Move distr params to simulation param generator

* Cleanup sim params output

* Print params when possible instead of entire genesis struct

* Update module param simulator keys

* Rename module params simulator keys

* Add/fix missing module params and implement SimParams

* UPdate sim test to accept params file

* Allow weights to be provided from file

* Create doc.go

* Remove TODO

* Implement MustMarshalJSONIndent

* Use mustMarshalJSONIndent for non-codec

* Remove TODO

* Fix doc.go

* Update points

* Update simapp/doc.go

Co-Authored-By: Alessio Treglia <quadrispro@ubuntu.com>

* Update simapp/doc.go

Co-Authored-By: Alessio Treglia <quadrispro@ubuntu.com>

* Cleanup appStateFn

* Use constants for simulation parameter keys

* Update msgs.go

* minor formatting

doc.go

@@ -0,0 +1,93 @@
+/*
+Package simapp implements a full fledged Cosmos SDK application used for executing
+simulation test suites.
+
+Simulation App
+
+The SimApp type defines an application used for running extensive simulation
+testing suites. It contains all core modules, including governance, staking,
+slashing, and distribution.
+
+Simulation is executed with various inputs including the number of blocks to
+simulate, the block size, whether the app should commit or not, the invariant
+checking period, and a seed which is used as a source of pseudo-randomness.
+
+In addition to the various inputs, simulation runs mainly in three modes:
+
+1. Completely random where the initial state, module parameters and simulation
+parameters are pseudo-randomly generated.
+
+2. From a genesis file where the initial state and the module parameters are defined.
+This mode is helpful for running simulations on a known state such as a live
+network export where a new (mostly likely breaking) version of the application
+needs to be tested.
+
+3. From a params file where the initial state is pseudo-randomly generated but the
+module and simulation parameters can be provided manually. This allows for a more
+controlled and deterministic simulation setup while allowing the state space to
+still be pseudo-randomly simulated.
+
+The simulation test suite also supports testing determinism and import/export
+functionality.
+
+Randomness
+
+Currently, simulation uses a single seed (integer) as a source for a PRNG by
+which all random operations are executed from. Any call to the PRNG changes all
+future operations as the internal state of the PRNG is modified. For example,
+if a new message type is created and needs to be simulated, the new introduced
+PRNG call will change all subsequent operations.
+
+This may can often be problematic when testing fixes to simulation faults. One
+current solution to this is to use a params file as mentioned above. In the future
+the simulation suite is expected to support a series of PRNGs that can be used
+uniquely per module and simulation component so that they will not effect each
+others state execution outcome.
+
+Usage
+
+To execute a completely pseudo-random simulation:
+
+ $ go test -mod=readonly github.com/cosmos/cosmos-sdk/simapp \
+	-run=TestFullAppSimulation \
+	-SimulationEnabled=true \
+	-SimulationNumBlocks=100 \
+	-SimulationBlockSize=200 \
+	-SimulationCommit=true \
+	-SimulationSeed=99 \
+	-SimulationPeriod=5 \
+	-v -timeout 24h
+
+To execute simulation from a genesis file:
+
+ $ go test -mod=readonly github.com/cosmos/cosmos-sdk/simapp \
+ 	-run=TestFullAppSimulation \
+ 	-SimulationEnabled=true \
+ 	-SimulationNumBlocks=100 \
+ 	-SimulationBlockSize=200 \
+ 	-SimulationCommit=true \
+ 	-SimulationSeed=99 \
+ 	-SimulationPeriod=5 \
+ 	-SimulationGenesis=/path/to/genesis.json \
+ 	-v -timeout 24h
+
+To execute simulation from a params file:
+
+ $ go test -mod=readonly github.com/cosmos/cosmos-sdk/simapp \
+	-run=TestFullAppSimulation \
+	-SimulationEnabled=true \
+	-SimulationNumBlocks=100 \
+	-SimulationBlockSize=200 \
+	-SimulationCommit=true \
+	-SimulationSeed=99 \
+	-SimulationPeriod=5 \
+	-SimulationParams=/path/to/params.json \
+	-v -timeout 24h
+
+Params
+
+Params that are provided to simulation from a JSON file are used to used to set
+both module parameters and simulation parameters. See sim_test.go for the full
+set of parameters that can be provided.
+*/
+package simapp

params.go

@@ -0,0 +1,23 @@
+package simapp
+
+// Simulation parameter constants
+const (
+	StakePerAccount                                    = "stake_per_account"
+	InitiallyBondedValidators                          = "initially_bonded_validators"
+	OpWeightDeductFee                                  = "op_weight_deduct_fee"
+	OpWeightMsgSend                                    = "op_weight_msg_send"
+	OpWeightSingleInputMsgMultiSend                    = "op_weight_single_input_msg_multisend"
+	OpWeightMsgSetWithdrawAddress                      = "op_weight_msg_set_withdraw_address"
+	OpWeightMsgWithdrawDelegationReward                = "op_weight_msg_withdraw_delegation_reward"
+	OpWeightMsgWithdrawValidatorCommission             = "op_weight_msg_withdraw_validator_commission"
+	OpWeightSubmitVotingSlashingTextProposal           = "op_weight_submit_voting_slashing_text_proposal"
+	OpWeightSubmitVotingSlashingCommunitySpendProposal = "op_weight_submit_voting_slashing_community_spend_proposal"
+	OpWeightSubmitVotingSlashingParamChangeProposal    = "op_weight_submit_voting_slashing_param_change_proposal"
+	OpWeightMsgDeposit                                 = "op_weight_msg_deposit"
+	OpWeightMsgCreateValidator                         = "op_weight_msg_create_validator"
+	OpWeightMsgEditValidator                           = "op_weight_msg_edit_validator"
+	OpWeightMsgDelegate                                = "op_weight_msg_delegate"
+	OpWeightMsgUndelegate                              = "op_weight_msg_undelegate"
+	OpWeightMsgBeginRedelegate                         = "op_weight_msg_begin_redelegate"
+	OpWeightMsgUnjail                                  = "op_weight_msg_unjail"
+)