test: Add fuzzer test with no-op transactions

This commit adds a new test that validates the transaction fuzzer's behavior
using no-operation transactions. The test ensures that the fuzzer can:
- Process transactions independently of application logic
- Complete a simulation successfully
- Maintain expected block height

The test is designed to be fast and focused, running for only 10 blocks with
minimal setup. This helps validate the fuzzer's core functionality without
being affected by application-specific behavior.

Resolves TODO in app/sim_test.go

app/sim_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/cosmos/cosmos-sdk/server"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 	simtestutil "github.com/cosmos/cosmos-sdk/testutil/sims"
 	simulation2 "github.com/cosmos/cosmos-sdk/types/simulation"
 	"github.com/cosmos/cosmos-sdk/x/simulation"
@@ -148,3 +149,71 @@ func TestAppStateDeterminism(t *testing.T) {
 		}
 	}
 }
+
+// TestFuzzerWithNoOpTxs tests the transaction fuzzer with no-operation transactions
+// to verify the fuzzer's behavior independently of the application logic.
+func TestFuzzerWithNoOpTxs(t *testing.T) {
+	if !sim.FlagEnabledValue {
+		t.Skip("skipping fuzzer simulation")
+	}
+
+	config := sim.NewConfigFromFlags()
+	config.InitialBlockHeight = 1
+	config.ExportParamsPath = ""
+	config.OnOperation = false
+	config.AllInvariants = false
+	config.ChainID = AppChainID
+	config.NumBlocks = 10 // Keep test short but meaningful
+
+	// Create a minimal application setup
+	logger := log.NewNopLogger()
+	db := dbm.NewMemDB()
+	dir, err := os.MkdirTemp("", "gaia-fuzzer-test")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	appOptions := make(simtestutil.AppOptionsMap, 0)
+	appOptions[flags.FlagHome] = dir
+	appOptions[server.FlagInvCheckPeriod] = sim.FlagPeriodValue
+
+	app := gaia.NewGaiaApp(
+		logger,
+		db,
+		nil,
+		true,
+		map[int64]bool{},
+		dir,
+		appOptions,
+		emptyWasmOption,
+		interBlockCacheOpt(),
+		baseapp.SetChainID(AppChainID),
+	)
+
+	// Create simulation manager with only no-op operations
+	operations := []simulation2.WeightedOperation{
+		{
+			Weight: 100,
+			Op: simulation2.Operation(func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context,
+				accs []simulation2.Account, chainID string) (simulation2.OperationMsg, []simulation2.FutureOperation, error) {
+				return simulation2.NewOperationMsg(&sdk.Msg{}, true, "", nil), nil, nil
+			}),
+		},
+	}
+
+	// Run simulation
+	_, _, err = simulation.SimulateFromSeed(
+		t,
+		os.Stdout,
+		app.BaseApp,
+		simtestutil.AppStateFn(app.AppCodec(), app.SimulationManager(), app.ModuleBasics.DefaultGenesis(app.AppCodec())),
+		simulation2.RandomAccounts,
+		operations,
+		app.BlockedModuleAccountAddrs(app.ModuleAccountAddrs()),
+		config,
+		app.AppCodec(),
+	)
+	require.NoError(t, err)
+
+	// Verify that simulation completed successfully
+	require.Equal(t, uint64(config.NumBlocks), app.LastBlockHeight())
+}