Add unit test for resource constraints precompile

Author: MishkaRogachev

arbos/constraints/constraints.go

@@ -23,7 +23,7 @@ type ResourceSet struct {
 	weights [multigas.NumResourceKind]ResourceWeight
 }
 
-const MaxResourceWeight = 1_000_000
+const MaxResourceWeight = 1_000_000 // 1e6
 
 // EmptyResourceSet creates a new set with all weights initialized to zero.
 func EmptyResourceSet() ResourceSet {
@@ -69,14 +69,18 @@ type ResourceConstraint struct {
 // AddToBacklog increases the constraint backlog given the multi-dimensional gas used multiplied by their weights.
 func (c *ResourceConstraint) AddToBacklog(gasUsed multigas.MultiGas) {
 	for resource, weight := range c.Resources.All() {
-		weightedGas := gasUsed.Get(resource) * uint64(weight)
+		if weight == 0 {
+			continue
+		}
+		weightedGas := arbmath.SaturatingUMul(gasUsed.Get(resource), uint64(weight))
 		c.Backlog = arbmath.SaturatingUAdd(c.Backlog, weightedGas)
 	}
 }
 
 // RemoveFromBacklog decreases the backlog by its target given the amount of time passed.
 func (c *ResourceConstraint) RemoveFromBacklog(timeElapsed uint64) {
-	c.Backlog = arbmath.SaturatingUSub(c.Backlog, timeElapsed*c.TargetPerSec)
+	amount := arbmath.SaturatingUMul(timeElapsed, c.TargetPerSec)
+	c.Backlog = arbmath.SaturatingUSub(c.Backlog, amount)
 }
 
 // constraintKey identifies a resource constraint. There can be only one constraint given the

precompiles/ArbResourceConstraints_test.go

@@ -0,0 +1,119 @@
+// Copyright 2025, Offchain Labs, Inc.
+// For license information, see https://github.com/OffchainLabs/nitro/blob/master/LICENSE.md
+
+package precompiles
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/ethereum/go-ethereum/arbitrum/multigas"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/crypto"
+
+	"github.com/offchainlabs/nitro/arbos/arbosState"
+	"github.com/offchainlabs/nitro/arbos/burn"
+	"github.com/offchainlabs/nitro/arbos/util"
+	"github.com/offchainlabs/nitro/util/testhelpers"
+)
+
+func setupResourceConstraintHandles(
+	t *testing.T,
+) (
+	*vm.EVM,
+	*arbosState.ArbosState,
+	*Context,
+	*ArbGasInfo,
+	*ArbOwner,
+) {
+	evm := newMockEVMForTesting()
+	caller := common.BytesToAddress(crypto.Keccak256([]byte{})[:20])
+	tracer := util.NewTracingInfo(evm, testhelpers.RandomAddress(), types.ArbosAddress, util.TracingDuringEVM)
+	state, err := arbosState.OpenArbosState(evm.StateDB, burn.NewSystemBurner(tracer, false))
+	Require(t, err)
+
+	arbGasInfo := &ArbGasInfo{}
+	arbOwner := &ArbOwner{}
+
+	callCtx := testContext(caller, evm)
+
+	return evm, state, callCtx, arbGasInfo, arbOwner
+}
+
+func TestStorageResourceConstraintsManagment(t *testing.T) {
+	t.Parallel()
+
+	evm, _, callCtx, arbGasInfo, arbOwner := setupResourceConstraintHandles(t)
+
+	// Expect error when setting empty resource constraints
+	err := arbOwner.SetResourceConstraint(callCtx, evm, []resourceWeight{}, 0, 0)
+	require.Error(t, err)
+
+	// Expect error when setting resource constraint with invalid weight
+	err = arbOwner.SetResourceConstraint(callCtx, evm, []resourceWeight{
+		{ResourceKind: multigas.ResourceKindComputation, Weight: 0},
+	}, 0, 0)
+	require.Error(t, err)
+
+	// Expect error when setting resource constraint with duplicate resource kinds
+	err = arbOwner.SetResourceConstraint(callCtx, evm, []resourceWeight{
+		{ResourceKind: multigas.ResourceKindComputation, Weight: 1},
+		{ResourceKind: multigas.ResourceKindComputation, Weight: 2},
+	}, 0, 0)
+	require.Error(t, err)
+
+	// Check that no resource constraints are set initially
+	rcs, err := arbGasInfo.ListResourceConstraints(callCtx, evm)
+	require.NoError(t, err)
+	require.Empty(t, rcs)
+
+	// Set a valid resource constraint
+	rc1 := []resourceWeight{
+		{ResourceKind: multigas.ResourceKindComputation, Weight: 1},
+		{ResourceKind: multigas.ResourceKindStorageAccess, Weight: 2},
+	}
+	err = arbOwner.SetResourceConstraint(callCtx, evm, rc1, 12, 10_000_000)
+	require.NoError(t, err)
+
+	// Verify the resource constraint was set
+	rcs, err = arbGasInfo.ListResourceConstraints(callCtx, evm)
+	require.NoError(t, err)
+	require.Len(t, rcs, 1)
+	require.Equal(t, uint32(12), rcs[0].PeriodSecs)
+	require.Equal(t, uint64(10_000_000), rcs[0].TargetPerSec)
+	require.Len(t, rcs[0].ResourceWeight, 2)
+	require.Contains(t, rcs[0].ResourceWeight, resourceWeight{ResourceKind: multigas.ResourceKindComputation, Weight: 1})
+	require.Contains(t, rcs[0].ResourceWeight, resourceWeight{ResourceKind: multigas.ResourceKindStorageAccess, Weight: 2})
+
+	// Set another valid resource constraint
+	rc2 := []resourceWeight{
+		{ResourceKind: multigas.ResourceKindStorageGrowth, Weight: 5},
+	}
+	err = arbOwner.SetResourceConstraint(callCtx, evm, rc2, 60, 50_000_000)
+	require.NoError(t, err)
+
+	// Verify both resource constraints are set
+	rcs, err = arbGasInfo.ListResourceConstraints(callCtx, evm)
+	require.NoError(t, err)
+	require.Len(t, rcs, 2)
+
+	// Remove the first resource constraint
+	err = arbOwner.ClearConstraint(callCtx, evm, rc1, 12)
+	require.NoError(t, err)
+
+	// Reset the second resource constraint with new values
+	err = arbOwner.SetResourceConstraint(callCtx, evm, rc2, 60, 20_000_000)
+	require.NoError(t, err)
+
+	// Verify only the updated second resource constraint remains
+	rcs, err = arbGasInfo.ListResourceConstraints(callCtx, evm)
+	require.NoError(t, err)
+	require.Len(t, rcs, 1)
+	require.Equal(t, uint32(60), rcs[0].PeriodSecs)
+	require.Equal(t, uint64(20_000_000), rcs[0].TargetPerSec)
+	require.Len(t, rcs[0].ResourceWeight, 1)
+	require.Contains(t, rcs[0].ResourceWeight, resourceWeight{ResourceKind: multigas.ResourceKindStorageGrowth, Weight: 5})
+}