feat(sim): implement the beginning of a replacement simulator

This change implements a replacement for the current simulator based
on testutil/network. Most of the changes are porting the module specific
message generators to no longer rely on SimulationState, and to generate
"real" messages, not simulator messages. The simulator driver is in
simapp, as part of the IntegationTestSuite.

The new approach aims to improve simulation in two important ways:

- Simulation should more closely mimic a real network. The current
simulator message delivery is implemented parallel to non-simulator
message delivery, leading to loss of fidelity and higher maintenance.
One symptom is cosmos#13843.
- Simulation should be layered on top of modules, not part of modules.
This means that modules should not import simulation packages, nor refer
to its generator package (x/module/simulation). This should eventually
fix cosmos#7622.

There are also downsides, however. Where the current simulator is too
high level, testutil/network is too low level: it runs a real network
of validators which is difficult to control. For example:

- AppHashes differ between runs, because modules may depend on non-
deterministic state such as block header timestamps.
- The validators runs in separate goroutines, which makes it hard to
query app state without introducing race conditions.
- Blocks are produced according tot time, and not under control by the
test driver. This makes it hard to trigger processing of messages in
particular blocks, which ruins determinism.

Some of the issues may be worked around, for example by forcing the
block headers to be deterministic; however, the real fix is to make
testutil/network itself deterministic, providing the goldilock level
of simulation: close enough to a real network, yet deterministic enough
to generate the same chain state for a given random seed.

A deterministic testutil/network is part of cosmos#18145.

Future work includes:

- Porting of the remaining module message generators.
- Generating (and verifying) deterministic AppHashes, allowing reliable
replay when a problematic message is detected. Depends on cosmos#18145.
- Save/reload of state for faster debugging cycles.
- Removal of the old simulator, most importantly the reference to it from
 module code.

 Updates cosmos#14753 (Simulator rewrite epic)
 Updates cosmos#7622 (reducing imports from modules to simulator)
 Updates cosmos#13843 (using real message delivery for simulation)

simapp/app.go

@@ -28,7 +28,6 @@ import (
 	authcodec "cosmossdk.io/x/auth/codec"
 	authkeeper "cosmossdk.io/x/auth/keeper"
 	"cosmossdk.io/x/auth/posthandler"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtx "cosmossdk.io/x/auth/tx"
 	txmodule "cosmossdk.io/x/auth/tx/config"
 	authtypes "cosmossdk.io/x/auth/types"
@@ -405,7 +404,7 @@ func NewSimApp(
 			txConfig,
 		),
 		accounts.NewAppModule(app.AccountsKeeper),
-		auth.NewAppModule(appCodec, app.AuthKeeper, authsims.RandomGenesisAccounts),
+		auth.NewAppModule(appCodec, app.AuthKeeper),
 		vesting.NewAppModule(app.AuthKeeper, app.BankKeeper),
 		bank.NewAppModule(appCodec, app.BankKeeper, app.AuthKeeper),
 		feegrantmodule.NewAppModule(appCodec, app.AuthKeeper, app.BankKeeper, app.FeeGrantKeeper, app.interfaceRegistry),
@@ -502,14 +501,7 @@ func NewSimApp(
 	// add test gRPC service for testing gRPC queries in isolation
 	testdata_pulsar.RegisterQueryServer(app.GRPCQueryRouter(), testdata_pulsar.QueryImpl{})
 
-	// create the simulation manager and define the order of the modules for deterministic simulations
-	//
-	// NOTE: this is not required apps that don't use the simulator for fuzz testing
-	// transactions
-	overrideModules := map[string]module.AppModuleSimulation{
-		authtypes.ModuleName: auth.NewAppModule(app.appCodec, app.AuthKeeper, authsims.RandomGenesisAccounts),
-	}
-	app.sm = module.NewSimulationManagerFromAppModules(app.ModuleManager.Modules, overrideModules)
+	app.sm = module.NewSimulationManagerFromAppModules(app.ModuleManager.Modules, nil)
 
 	app.sm.RegisterStoreDecoders()
 

simapp/app_v2.go

@@ -12,10 +12,7 @@ import (
 	"cosmossdk.io/depinject"
 	"cosmossdk.io/log"
 	storetypes "cosmossdk.io/store/types"
-	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
-	authtypes "cosmossdk.io/x/auth/types"
 	authzkeeper "cosmossdk.io/x/authz/keeper"
 	bankkeeper "cosmossdk.io/x/bank/keeper"
 	circuitkeeper "cosmossdk.io/x/circuit/keeper"
@@ -234,14 +231,7 @@ func NewSimApp(
 	// add test gRPC service for testing gRPC queries in isolation
 	testdata_pulsar.RegisterQueryServer(app.GRPCQueryRouter(), testdata_pulsar.QueryImpl{})
 
-	// create the simulation manager and define the order of the modules for deterministic simulations
-	//
-	// NOTE: this is not required apps that don't use the simulator for fuzz testing
-	// transactions
-	overrideModules := map[string]module.AppModuleSimulation{
-		authtypes.ModuleName: auth.NewAppModule(app.appCodec, app.AuthKeeper, authsims.RandomGenesisAccounts),
-	}
-	app.sm = module.NewSimulationManagerFromAppModules(app.ModuleManager.Modules, overrideModules)
+	app.sm = module.NewSimulationManagerFromAppModules(app.ModuleManager.Modules, nil)
 
 	app.sm.RegisterStoreDecoders()
 

simapp/testutil_network_test.go

@@ -1,27 +1,78 @@
 package simapp_test
 
 import (
+	"fmt"
+	"math/rand"
 	"testing"
 	"time"
 
+	cmtcfg "github.com/cometbft/cometbft/config"
+	"github.com/cosmos/go-bip39"
 	"github.com/stretchr/testify/suite"
 
+	sdkmath "cosmossdk.io/math"
 	"cosmossdk.io/simapp"
+	authsim "cosmossdk.io/x/auth/simulation"
+	banksim "cosmossdk.io/x/bank/simulation"
+	govsim "cosmossdk.io/x/gov/simulation"
 
+	"github.com/cosmos/cosmos-sdk/client/grpc/cmtservice"
+	servertypes "github.com/cosmos/cosmos-sdk/server/types"
 	"github.com/cosmos/cosmos-sdk/testutil/network"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	simtypes "github.com/cosmos/cosmos-sdk/types/simulation"
+	xsim "github.com/cosmos/cosmos-sdk/x/simulation"
 )
 
 type IntegrationTestSuite struct {
 	suite.Suite
 
-	network network.NetworkI
+	network  network.NetworkI
+	cfg      network.Config
+	v0app    *simapp.SimApp
+	rand     *rand.Rand
+	accounts []simtypes.Account
 }
 
 func (s *IntegrationTestSuite) SetupSuite() {
 	s.T().Log("setting up integration test suite")
 
+	s.rand = rand.New(rand.NewSource(42))
+	params := xsim.RandomParams(s.rand)
+	s.accounts = simtypes.RandomAccounts(s.rand, params.NumKeys())
+	// TODO: improve this hack to get at the bank keeper, or replace
+	// it with RPC queries.
+	s.cfg = network.DefaultConfig(func() network.TestFixture {
+		fixture := simapp.NewTestNetworkFixture()
+		appCtr := fixture.AppConstructor
+		fixture.AppConstructor = func(val network.ValidatorI) servertypes.Application {
+			app := appCtr(val)
+			s.v0app = app.(*simapp.SimApp)
+			return app
+		}
+		return fixture
+	})
+	s.cfg.NumValidators = s.rand.Intn(10)
+	s.cfg.ChainID = fmt.Sprintf("chainid-simapp-%x", s.rand.Uint64())
+	s.cfg.GenesisTime = time.Unix(0, 0)
+	s.cfg.FuzzConnConfig = cmtcfg.DefaultFuzzConnConfig()
+	s.cfg.FuzzConnConfig.ProbDropConn = .1
+	for i := 0; i < s.cfg.NumValidators; i++ {
+		entropy := make([]byte, 256/8)
+		n, _ := s.rand.Read(entropy)
+		mnemonic, err := bip39.NewMnemonic(entropy[:n])
+		if err != nil {
+			s.T().Fatal(err)
+		}
+		s.cfg.Mnemonics = append(s.cfg.Mnemonics, mnemonic)
+	}
+	initialStake := sdkmath.NewInt(s.rand.Int63n(1e12))
+	const numBonded = 3
+	banksim.RandomizedGenState(s.rand, s.cfg.GenesisState, s.cfg.Codec, s.cfg.BondDenom, s.accounts)
+	authsim.RandomizedGenState(s.rand, s.cfg.GenesisState, s.cfg.Codec, s.cfg.BondDenom, s.accounts, initialStake, numBonded, s.cfg.GenesisTime)
+	govsim.RandomizedGenState(s.rand, s.cfg.GenesisState, s.cfg.Codec, s.cfg.BondDenom)
 	var err error
-	s.network, err = network.New(s.T(), s.T().TempDir(), network.DefaultConfig(simapp.NewTestNetworkFixture))
+	s.network, err = network.New(s.T(), s.T().TempDir(), s.cfg)
 	s.Require().NoError(err)
 
 	h, err := s.network.WaitForHeight(1)
@@ -38,6 +89,93 @@ func (s *IntegrationTestSuite) TestNetwork_Liveness() {
 	s.Require().NoError(err, "expected to reach 10 blocks; got %d", h)
 }
 
+func (s *IntegrationTestSuite) TestSimulation() {
+	v0 := s.network.GetValidators()[0]
+	v0app := s.v0app
+	clientCtx := v0.GetClientCtx()
+	ctx := v0app.NewContext(true)
+
+	voteGen := govsim.NewVoteGenerator()
+	var futureVotes []govsim.Vote
+	txEnc := clientCtx.TxConfig.TxEncoder()
+	queryClient := cmtservice.NewServiceClient(clientCtx)
+	generate := func(r *rand.Rand) sdk.Tx {
+		bankSend := func(to, from simtypes.Account) sdk.Tx {
+			return banksim.GenerateMsgSend(s.rand, ctx, clientCtx, v0.GetMoniker(), to, from, v0app.BankKeeper, v0app.AuthKeeper)
+		}
+		generators := []func() sdk.Tx{
+			func() sdk.Tx {
+				from, _ := simtypes.RandomAcc(s.rand, s.accounts)
+				to, _ := simtypes.RandomAcc(s.rand, s.accounts)
+				// disallow sending money to yourself.
+				for from.PubKey.Equals(to.PubKey) {
+					to, _ = simtypes.RandomAcc(s.rand, s.accounts)
+				}
+				return bankSend(to, from)
+			},
+			func() sdk.Tx {
+				macc := v0app.AuthKeeper.GetModuleAccount(ctx, banksim.DistributionModuleName)
+				to := simtypes.Account{
+					PubKey:  macc.GetPubKey(),
+					Address: macc.GetAddress(),
+				}
+				from, _ := simtypes.RandomAcc(s.rand, s.accounts)
+				return bankSend(to, from)
+			},
+			func() sdk.Tx {
+				const numModuleAccs = 2
+				return banksim.GenerateMsgMultiSendToModuleAccount(s.rand, ctx, clientCtx, v0.GetMoniker(), s.accounts, v0app.BankKeeper, v0app.AuthKeeper, numModuleAccs)
+			},
+			func() sdk.Tx {
+				proposal := authsim.GenerateMsgUpdateParams(s.rand)
+				tx := govsim.GenerateMsgSubmitProposal(s.rand, ctx, clientCtx.TxConfig, s.accounts, v0app.AuthKeeper, v0app.BankKeeper, v0app.GovKeeper, []sdk.Msg{proposal})
+				votes := voteGen.GenerateVotes(s.rand, ctx, clientCtx.TxConfig, s.accounts, v0app.AuthKeeper, v0app.BankKeeper, v0app.GovKeeper)
+				futureVotes = append(futureVotes, votes...)
+				return tx
+			},
+			func() sdk.Tx {
+				return govsim.GenerateMsgDeposit(s.rand, ctx, clientCtx.TxConfig, s.accounts, v0app.AuthKeeper, v0app.BankKeeper, v0app.GovKeeper)
+			},
+			func() sdk.Tx {
+				return banksim.GenerateMsgMultiSend(s.rand, ctx, clientCtx, v0.GetMoniker(), s.accounts, v0app.BankKeeper, v0app.AuthKeeper)
+			},
+			func() sdk.Tx {
+				return govsim.GenerateMsgVoteWeighted(s.rand, ctx, clientCtx.TxConfig, s.accounts, v0app.AuthKeeper, v0app.BankKeeper, v0app.GovKeeper)
+			},
+			func() sdk.Tx {
+				return govsim.GenerateMsgCancelProposal(s.rand, ctx, clientCtx.TxConfig, s.accounts, v0app.AuthKeeper, v0app.BankKeeper, v0app.GovKeeper)
+			},
+		}
+		idx := s.rand.Intn(len(generators))
+		return generators[idx]()
+	}
+	for i := 0; i < 100; i++ {
+		tx := generate(s.rand)
+		txBytes, err := txEnc(tx)
+		s.Require().NoError(err)
+		_, err = clientCtx.BroadcastTxAsync(txBytes)
+		s.Require().NoError(err)
+		res, err := queryClient.GetLatestBlock(ctx, &cmtservice.GetLatestBlockRequest{})
+		s.Require().NoError(err)
+		latestTime := res.SdkBlock.Header.Time
+		for j := len(futureVotes) - 1; j >= 0; j-- {
+			v := futureVotes[j]
+			if v.BlockTime.Before(latestTime) {
+				continue
+			}
+			futureVotes = append(futureVotes[:j], futureVotes[j+1:]...)
+			txBytes, err := txEnc(v.Vote)
+			s.Require().NoError(err)
+			_, err = clientCtx.BroadcastTxAsync(txBytes)
+			s.Require().NoError(err)
+		}
+		if i%10 == 0 {
+			err := s.network.WaitForNextBlock()
+			s.Require().NoError(err)
+		}
+	}
+}
+
 func TestIntegrationTestSuite(t *testing.T) {
 	suite.Run(t, new(IntegrationTestSuite))
 }

tests/integration/bank/keeper/deterministic_test.go

@@ -12,7 +12,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	_ "cosmossdk.io/x/auth/tx/config"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/bank"
@@ -98,7 +97,7 @@ func initDeterministicFixture(t *testing.T) *deterministicFixture {
 		log.NewNopLogger(),
 	)
 
-	authModule := auth.NewAppModule(cdc, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(cdc, accountKeeper)
 	bankModule := bank.NewAppModule(cdc, bankKeeper, accountKeeper)
 
 	integrationApp := integration.NewIntegrationApp(newCtx, logger, keys, cdc, map[string]appmodule.AppModule{

tests/integration/distribution/keeper/msg_server_test.go

@@ -15,7 +15,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/bank"
 	bankkeeper "cosmossdk.io/x/bank/keeper"
@@ -115,7 +114,7 @@ func initFixture(t *testing.T) *fixture {
 		cdc, runtime.NewKVStoreService(keys[distrtypes.StoreKey]), accountKeeper, bankKeeper, stakingKeeper, poolKeeper, distrtypes.ModuleName, authority.String(),
 	)
 
-	authModule := auth.NewAppModule(cdc, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(cdc, accountKeeper)
 	bankModule := bank.NewAppModule(cdc, bankKeeper, accountKeeper)
 	stakingModule := staking.NewAppModule(cdc, stakingKeeper, accountKeeper, bankKeeper)
 	distrModule := distribution.NewAppModule(cdc, distrKeeper, accountKeeper, bankKeeper, stakingKeeper, poolKeeper)

tests/integration/evidence/keeper/infraction_test.go

@@ -18,7 +18,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/bank"
 	bankkeeper "cosmossdk.io/x/bank/keeper"
@@ -130,7 +129,7 @@ func initFixture(tb testing.TB) *fixture {
 	router = router.AddRoute(evidencetypes.RouteEquivocation, testEquivocationHandler(evidenceKeeper))
 	evidenceKeeper.SetRouter(router)
 
-	authModule := auth.NewAppModule(cdc, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(cdc, accountKeeper)
 	bankModule := bank.NewAppModule(cdc, bankKeeper, accountKeeper)
 	stakingModule := staking.NewAppModule(cdc, stakingKeeper, accountKeeper, bankKeeper)
 	slashingModule := slashing.NewAppModule(cdc, slashingKeeper, accountKeeper, bankKeeper, stakingKeeper, cdc.InterfaceRegistry())

tests/integration/example/example_test.go

@@ -11,7 +11,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/mint"
 	mintkeeper "cosmossdk.io/x/mint/keeper"
@@ -50,7 +49,7 @@ func Example() {
 	)
 
 	// subspace is nil because we don't test params (which is legacy anyway)
-	authModule := auth.NewAppModule(encodingCfg.Codec, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(encodingCfg.Codec, accountKeeper)
 
 	// here bankkeeper and staking keeper is nil because we are not testing them
 	// subspace is nil because we don't test params (which is legacy anyway)
@@ -139,7 +138,7 @@ func Example_oneModule() {
 	)
 
 	// subspace is nil because we don't test params (which is legacy anyway)
-	authModule := auth.NewAppModule(encodingCfg.Codec, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(encodingCfg.Codec, accountKeeper)
 
 	// create the application and register all the modules from the previous step
 	integrationApp := integration.NewIntegrationApp(

tests/integration/gov/keeper/keeper_test.go

@@ -10,7 +10,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/bank"
 	bankkeeper "cosmossdk.io/x/bank/keeper"
@@ -121,7 +120,7 @@ func initFixture(tb testing.TB) *fixture {
 	err = govKeeper.Params.Set(newCtx, v1.DefaultParams())
 	assert.NilError(tb, err)
 
-	authModule := auth.NewAppModule(cdc, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(cdc, accountKeeper)
 	bankModule := bank.NewAppModule(cdc, bankKeeper, accountKeeper)
 	stakingModule := staking.NewAppModule(cdc, stakingKeeper, accountKeeper, bankKeeper)
 	govModule := gov.NewAppModule(cdc, govKeeper, accountKeeper, bankKeeper, poolKeeper)

tests/integration/staking/keeper/common_test.go

@@ -12,7 +12,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/bank"
 	bankkeeper "cosmossdk.io/x/bank/keeper"
@@ -137,7 +136,7 @@ func initFixture(tb testing.TB) *fixture {
 
 	stakingKeeper := stakingkeeper.NewKeeper(cdc, runtime.NewKVStoreService(keys[types.StoreKey]), accountKeeper, bankKeeper, authority.String(), addresscodec.NewBech32Codec(sdk.Bech32PrefixValAddr), addresscodec.NewBech32Codec(sdk.Bech32PrefixConsAddr))
 
-	authModule := auth.NewAppModule(cdc, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(cdc, accountKeeper)
 	bankModule := bank.NewAppModule(cdc, bankKeeper, accountKeeper)
 	stakingModule := staking.NewAppModule(cdc, stakingKeeper, accountKeeper, bankKeeper)
 

tests/integration/staking/keeper/deterministic_test.go

@@ -13,7 +13,6 @@ import (
 	storetypes "cosmossdk.io/store/types"
 	"cosmossdk.io/x/auth"
 	authkeeper "cosmossdk.io/x/auth/keeper"
-	authsims "cosmossdk.io/x/auth/simulation"
 	authtypes "cosmossdk.io/x/auth/types"
 	"cosmossdk.io/x/bank"
 	bankkeeper "cosmossdk.io/x/bank/keeper"
@@ -108,7 +107,7 @@ func initDeterministicFixture(t *testing.T) *deterministicFixture {
 
 	stakingKeeper := stakingkeeper.NewKeeper(cdc, runtime.NewKVStoreService(keys[stakingtypes.StoreKey]), accountKeeper, bankKeeper, authority.String(), addresscodec.NewBech32Codec(sdk.Bech32PrefixValAddr), addresscodec.NewBech32Codec(sdk.Bech32PrefixConsAddr))
 
-	authModule := auth.NewAppModule(cdc, accountKeeper, authsims.RandomGenesisAccounts)
+	authModule := auth.NewAppModule(cdc, accountKeeper)
 	bankModule := bank.NewAppModule(cdc, bankKeeper, accountKeeper)
 	stakingModule := staking.NewAppModule(cdc, stakingKeeper, accountKeeper, bankKeeper)