fix(simulations): allow simulations to pass even if Interchain Accounts

simulation handlers are nonexistent.

This commit works around the issue described here: cosmos/ibc-go#1352

app/app.go

@@ -617,6 +617,7 @@ func New(
 		ibc.NewAppModule(app.IBCKeeper),
 		didmodule.NewAppModule(appCodec, app.DidKeeper, app.AccountKeeper, app.BankKeeper),
 		app.transferModule,
+		NewICAHostSimModule(icaModule, appCodec),
 		// this line is used by starport scaffolding # stargate/app/appModule
 	)
 	app.sm.RegisterStoreDecoders()

app/icahost_sim_helper.go

@@ -0,0 +1,69 @@
+package app
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/rand"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/module"
+	simtypes "github.com/cosmos/cosmos-sdk/types/simulation"
+	ica "github.com/cosmos/ibc-go/v3/modules/apps/27-interchain-accounts"
+	icatypes "github.com/cosmos/ibc-go/v3/modules/apps/27-interchain-accounts/types"
+)
+
+type ICAHostSimModule struct {
+	ica.AppModule
+	ica.AppModuleBasic
+	cdc codec.Codec
+}
+
+var (
+	_ module.AppModule           = ICAHostSimModule{}
+	_ module.AppModuleBasic      = ICAHostSimModule{}
+	_ module.AppModuleSimulation = ICAHostSimModule{}
+)
+
+func NewICAHostSimModule(baseModule ica.AppModule, cdc codec.Codec) ICAHostSimModule {
+	return ICAHostSimModule{
+		cdc:            cdc,
+		AppModule:      baseModule,
+		AppModuleBasic: baseModule.AppModuleBasic,
+	}
+}
+
+// ICAHostSimModuleSimulation functions
+// This thing does the bare minimum to avoid simulation panic-ing for missing state data.
+
+// GenerateGenesisState creates a randomized GenState of the ica module.
+func (i ICAHostSimModule) GenerateGenesisState(simState *module.SimulationState) {
+	genesis := icatypes.DefaultGenesis()
+
+	bz, err := json.MarshalIndent(&genesis, "", " ")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("Selected randomly generated %s parameters:\n%s\n", icatypes.ModuleName, bz)
+	simState.GenState[icatypes.ModuleName] = simState.Cdc.MustMarshalJSON(genesis)
+}
+
+// ProposalContents returns all the ica content functions used to
+// simulate governance proposals.
+func (ICAHostSimModule) ProposalContents(simState module.SimulationState) []simtypes.WeightedProposalContent {
+	return nil
+}
+
+// RandomizedParams creates randomized ica param changes for the simulator.
+func (ICAHostSimModule) RandomizedParams(*rand.Rand) []simtypes.ParamChange {
+	return nil
+}
+
+// RegisterStoreDecoder registers a decoder for ica module's types
+func (ICAHostSimModule) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry) {
+}
+
+// WeightedOperations returns the all the gov module operations with their respective weights.
+func (ICAHostSimModule) WeightedOperations(_ module.SimulationState) []simtypes.WeightedOperation {
+	return nil
+}