Refactor: Move gas fee check to own file with test (#71)

Author: hazim-j

internal/testutils/checksmock.go

@@ -1,6 +1,8 @@
 package testutils
 
 import (
+	"math/big"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/stackup-wallet/stackup-bundler/pkg/entrypoint"
 )
@@ -28,3 +30,9 @@ func MockGetNotStake(addr common.Address) (*entrypoint.IStakeManagerDepositInfo,
 func MockGetNotStakeZeroDeposit(addr common.Address) (*entrypoint.IStakeManagerDepositInfo, error) {
 	return NonStakedZeroDepositInfo, nil
 }
+
+func GetMockGasTipFunc(val *big.Int) func() (*big.Int, error) {
+	return func() (*big.Int, error) {
+		return val, nil
+	}
+}

pkg/modules/checks/sanitychecks.go renamed to pkg/modules/checks/gasfee.go

@@ -1,18 +1,16 @@
 package checks
 
 import (
-	"context"
 	"fmt"
 
-	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/stackup-wallet/stackup-bundler/pkg/userop"
 )
 
-// The maxFeePerGas and maxPriorityFeePerGas are above a configurable minimum value that the client
-// is willing to accept. At the minimum, they are sufficiently high to be included with the current
-// block.basefee.
-func checkFeePerGas(eth *ethclient.Client, op *userop.UserOperation) error {
-	tip, err := eth.SuggestGasTipCap(context.Background())
+// ValidateFeePerGas checks the maxFeePerGas and maxPriorityFeePerGas are above a configurable minimum value
+// that the client is willing to accept. At the minimum, they are sufficiently high to be included with the
+// current block.basefee.
+func ValidateFeePerGas(op *userop.UserOperation, gt GetGasTipFunc) error {
+	tip, err := gt()
 	if err != nil {
 		return err
 	}

pkg/modules/checks/gasfee_test.go

@@ -0,0 +1,78 @@
+package checks
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/stackup-wallet/stackup-bundler/internal/testutils"
+)
+
+// TestMPFLessThanGasTip calls checks.ValidateFeePerGas with a maxPriorityFeePerGas < gas tip. Expect error.
+func TestMPFLessThanGasTip(t *testing.T) {
+	op := testutils.MockValidInitUserOp()
+	gt := testutils.GetMockGasTipFunc(big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big1))
+	err := ValidateFeePerGas(op, gt)
+
+	if err == nil {
+		t.Fatal("got nil, want err")
+	}
+}
+
+// TestMPFEqualGasTip calls checks.ValidateFeePerGas with a maxPriorityFeePerGas == gas tip. Expect nil.
+func TestMPFEqualGasTip(t *testing.T) {
+	op := testutils.MockValidInitUserOp()
+	gt := testutils.GetMockGasTipFunc(big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big0))
+	err := ValidateFeePerGas(op, gt)
+
+	if err != nil {
+		t.Fatalf("got %v, want nil", err)
+	}
+}
+
+// TestMPFMoreThanGasTip calls checks.ValidateFeePerGas with a maxPriorityFeePerGas > gas tip. Expect nil.
+func TestMPFMoreThanGasTip(t *testing.T) {
+	op := testutils.MockValidInitUserOp()
+	gt := testutils.GetMockGasTipFunc(big.NewInt(0).Sub(op.MaxPriorityFeePerGas, common.Big1))
+	err := ValidateFeePerGas(op, gt)
+
+	if err != nil {
+		t.Fatalf("got %v, want nil", err)
+	}
+}
+
+// TestMFLessThanMPF calls checks.ValidateFeePerGas with a MaxFeePerGas < maxPriorityFeePerGas. Expect error.
+func TestMFLessThanMPF(t *testing.T) {
+	op := testutils.MockValidInitUserOp()
+	gt := testutils.GetMockGasTipFunc(big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big0))
+	op.MaxFeePerGas = big.NewInt(0).Sub(op.MaxPriorityFeePerGas, common.Big1)
+	err := ValidateFeePerGas(op, gt)
+
+	if err == nil {
+		t.Fatal("got nil, want err")
+	}
+}
+
+// TestMFEqualMPF calls checks.ValidateFeePerGas with a MaxFeePerGas == maxPriorityFeePerGas. Expect nil.
+func TestMFEqualMPF(t *testing.T) {
+	op := testutils.MockValidInitUserOp()
+	gt := testutils.GetMockGasTipFunc(big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big0))
+	op.MaxFeePerGas = big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big0)
+	err := ValidateFeePerGas(op, gt)
+
+	if err != nil {
+		t.Fatalf("got %v, want nil", err)
+	}
+}
+
+// TestMFMoreThanMPF calls checks.ValidateFeePerGas with a MaxFeePerGas > maxPriorityFeePerGas. Expect nil.
+func TestMFMoreThanMPF(t *testing.T) {
+	op := testutils.MockValidInitUserOp()
+	gt := testutils.GetMockGasTipFunc(big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big0))
+	op.MaxFeePerGas = big.NewInt(0).Add(op.MaxPriorityFeePerGas, common.Big1)
+	err := ValidateFeePerGas(op, gt)
+
+	if err != nil {
+		t.Fatalf("got %v, want nil", err)
+	}
+}

pkg/modules/checks/standalone.go

@@ -35,6 +35,7 @@ func New(rpc *rpc.Client, maxVerificationGas *big.Int, tracer string) *Standalon
 func (s *Standalone) ValidateOpValues() modules.UserOpHandlerFunc {
 	return func(ctx *modules.UserOpHandlerCtx) error {
 		gc := getCodeWithEthClient(s.eth)
+		gt := getGasTipWithEthClient(s.eth)
 		gs, err := getStakeWithEthClient(ctx, s.eth)
 		if err != nil {
 			return err
@@ -46,7 +47,7 @@ func (s *Standalone) ValidateOpValues() modules.UserOpHandlerFunc {
 		g.Go(func() error { return ValidateVerificationGas(ctx.UserOp, s.maxVerificationGas) })
 		g.Go(func() error { return ValidatePaymasterAndData(ctx.UserOp, gc, gs) })
 		g.Go(func() error { return ValidateCallGasLimit(ctx.UserOp) })
-		g.Go(func() error { return checkFeePerGas(s.eth, ctx.UserOp) })
+		g.Go(func() error { return ValidateFeePerGas(ctx.UserOp, gt) })
 
 		return g.Wait()
 	}

pkg/modules/checks/utils.go

@@ -2,6 +2,7 @@ package checks
 
 import (
 	"context"
+	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/ethclient"
@@ -15,6 +16,10 @@ type GetCodeFunc = func(addr common.Address) ([]byte, error)
 // GetStakeFunc provides a general interface for retrieving the EntryPoint stake for a given address.
 type GetStakeFunc = func(entity common.Address) (*entrypoint.IStakeManagerDepositInfo, error)
 
+// GetGasTipFunc provides a general interface for retrieving an EIP-1559 style gas tip to allow for timely
+// execution of a transaction.
+type GetGasTipFunc = func() (*big.Int, error)
+
 // getCodeWithEthClient returns a GetCodeFunc that uses an eth client to call eth_getCode.
 func getCodeWithEthClient(eth *ethclient.Client) GetCodeFunc {
 	return func(addr common.Address) ([]byte, error) {
@@ -40,3 +45,10 @@ func getStakeWithEthClient(ctx *modules.UserOpHandlerCtx, eth *ethclient.Client)
 		return &dep, nil
 	}, nil
 }
+
+// getGasTipWithEthClient returns a GetGasTipFunc that uses an eth client to call eth_maxPriorityFeePerGas.
+func getGasTipWithEthClient(eth *ethclient.Client) GetGasTipFunc {
+	return func() (*big.Int, error) {
+		return eth.SuggestGasTipCap(context.Background())
+	}
+}