fix(devnet-sdk): ensure balances are comparable

In error cases, make sure we can still compare resulting balances
without crashing.

In particular, this makes interop_smoke_test skip properly if it can't
find a funded wallet to use.

devnet-sdk/system/wallet.go

@@ -3,6 +3,7 @@ package system
 import (
 	"context"
 	"fmt"
+	"math/big"
 	"strings"
 
 	"github.com/ethereum-optimism/optimism/devnet-sdk/types"
@@ -52,12 +53,12 @@ func (w *wallet) SendETH(to types.Address, amount types.Balance) types.WriteInvo
 func (w *wallet) Balance() types.Balance {
 	client, err := w.chain.getClient()
 	if err != nil {
-		return types.Balance{}
+		return types.NewBalance(new(big.Int))
 	}
 
 	balance, err := client.BalanceAt(context.Background(), w.address, nil)
 	if err != nil {
-		return types.Balance{}
+		return types.NewBalance(new(big.Int))
 	}
 
 	return types.NewBalance(balance)

devnet-sdk/system/wallet_test.go

@@ -0,0 +1,92 @@
+package system
+
+import (
+	"context"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum-optimism/optimism/devnet-sdk/types"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+)
+
+// testWallet is a minimal wallet implementation for testing balance functionality
+type testWallet struct {
+	privateKey types.Key
+	address    types.Address
+	chain      *mockChainForBalance // Use concrete type to access mock client directly
+}
+
+func (w *testWallet) Balance() types.Balance {
+	// Use the mock client directly instead of going through getClient()
+	balance, err := w.chain.client.BalanceAt(context.Background(), w.address, nil)
+	if err != nil {
+		return types.NewBalance(new(big.Int))
+	}
+
+	return types.NewBalance(balance)
+}
+
+// mockEthClient implements a mock ethereum client for testing
+type mockEthClient struct {
+	mock.Mock
+}
+
+func (m *mockEthClient) BalanceAt(ctx context.Context, account types.Address, blockNumber *big.Int) (*big.Int, error) {
+	args := m.Called(ctx, account, blockNumber)
+	if args.Get(0) == nil {
+		return nil, args.Error(1)
+	}
+	return args.Get(0).(*big.Int), args.Error(1)
+}
+
+// mockChainForBalance implements just enough of the chain interface for balance testing
+type mockChainForBalance struct {
+	mock.Mock
+	client *mockEthClient
+}
+
+func TestWalletBalance(t *testing.T) {
+	tests := []struct {
+		name          string
+		setupMock     func(*mockChainForBalance)
+		expectedValue *big.Int
+	}{
+		{
+			name: "successful balance fetch",
+			setupMock: func(m *mockChainForBalance) {
+				balance := big.NewInt(1000000000000000000) // 1 ETH
+				m.client.On("BalanceAt", mock.Anything, mock.Anything, mock.Anything).Return(balance, nil)
+			},
+			expectedValue: big.NewInt(1000000000000000000),
+		},
+		{
+			name: "balance fetch error returns zero",
+			setupMock: func(m *mockChainForBalance) {
+				m.client.On("BalanceAt", mock.Anything, mock.Anything, mock.Anything).Return(nil, assert.AnError)
+			},
+			expectedValue: new(big.Int),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mockChain := &mockChainForBalance{
+				client: new(mockEthClient),
+			}
+			tt.setupMock(mockChain)
+
+			w := &testWallet{
+				privateKey: "test-key",
+				address:    types.Address{},
+				chain:      mockChain,
+			}
+
+			balance := w.Balance()
+			assert.Equal(t, 0, balance.Int.Cmp(tt.expectedValue))
+
+			mockChain.AssertExpectations(t)
+			mockChain.client.AssertExpectations(t)
+		})
+	}
+}

devnet-sdk/types/balance.go

@@ -35,16 +35,34 @@ func (b Balance) Mul(f float64) Balance {
 
 // GreaterThan returns true if this balance is greater than other
 func (b Balance) GreaterThan(other Balance) bool {
+	if b.Int == nil {
+		return false
+	}
+	if other.Int == nil {
+		return true
+	}
 	return b.Int.Cmp(other.Int) > 0
 }
 
 // LessThan returns true if this balance is less than other
 func (b Balance) LessThan(other Balance) bool {
+	if b.Int == nil {
+		return other.Int != nil
+	}
+	if other.Int == nil {
+		return false
+	}
 	return b.Int.Cmp(other.Int) < 0
 }
 
 // Equal returns true if this balance equals other
 func (b Balance) Equal(other Balance) bool {
+	if b.Int == nil {
+		return other.Int == nil
+	}
+	if other.Int == nil {
+		return false
+	}
 	return b.Int.Cmp(other.Int) == 0
 }
 
@@ -59,7 +77,7 @@ func (b Balance) LogValue() slog.Value {
 
 	// 1 ETH = 1e18 Wei
 	if eth.Cmp(new(big.Float).SetFloat64(0.001)) >= 0 {
-		str := eth.Text('g', 3)
+		str := eth.Text('f', 0)
 		return slog.StringValue(fmt.Sprintf("%s ETH", str))
 	}
 

devnet-sdk/types/balance_test.go

@@ -3,6 +3,8 @@ package types
 import (
 	"math/big"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestNewBalance(t *testing.T) {
@@ -87,61 +89,180 @@ func TestBalance_Mul(t *testing.T) {
 	}
 }
 
-func TestBalance_Comparisons(t *testing.T) {
+func TestBalanceComparisons(t *testing.T) {
 	tests := []struct {
-		a, b       int64
-		gt, lt, eq bool
+		name     string
+		balance1 Balance
+		balance2 Balance
+		greater  bool
+		less     bool
+		equal    bool
 	}{
-		{100, 200, false, true, false},
-		{200, 100, true, false, false},
-		{100, 100, false, false, true},
-		{0, 100, false, true, false},
+		{
+			name:     "both nil",
+			balance1: Balance{},
+			balance2: Balance{},
+			greater:  false,
+			less:     false,
+			equal:    true,
+		},
+		{
+			name:     "first nil",
+			balance1: Balance{},
+			balance2: NewBalance(big.NewInt(100)),
+			greater:  false,
+			less:     true,
+			equal:    false,
+		},
+		{
+			name:     "second nil",
+			balance1: NewBalance(big.NewInt(100)),
+			balance2: Balance{},
+			greater:  true,
+			less:     false,
+			equal:    false,
+		},
+		{
+			name:     "first greater",
+			balance1: NewBalance(big.NewInt(200)),
+			balance2: NewBalance(big.NewInt(100)),
+			greater:  true,
+			less:     false,
+			equal:    false,
+		},
+		{
+			name:     "second greater",
+			balance1: NewBalance(big.NewInt(100)),
+			balance2: NewBalance(big.NewInt(200)),
+			greater:  false,
+			less:     true,
+			equal:    false,
+		},
+		{
+			name:     "equal values",
+			balance1: NewBalance(big.NewInt(100)),
+			balance2: NewBalance(big.NewInt(100)),
+			greater:  false,
+			less:     false,
+			equal:    true,
+		},
+		{
+			name:     "zero values",
+			balance1: NewBalance(new(big.Int)),
+			balance2: NewBalance(new(big.Int)),
+			greater:  false,
+			less:     false,
+			equal:    true,
+		},
 	}
 
 	for _, tt := range tests {
-		a := NewBalance(big.NewInt(tt.a))
-		b := NewBalance(big.NewInt(tt.b))
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.greater, tt.balance1.GreaterThan(tt.balance2), "GreaterThan check failed")
+			assert.Equal(t, tt.less, tt.balance1.LessThan(tt.balance2), "LessThan check failed")
+			assert.Equal(t, tt.equal, tt.balance1.Equal(tt.balance2), "Equal check failed")
+		})
+	}
+}
 
-		if got := a.GreaterThan(b); got != tt.gt {
-			t.Errorf("GreaterThan(%v, %v) = %v, want %v", tt.a, tt.b, got, tt.gt)
-		}
+func TestBalanceArithmetic(t *testing.T) {
+	tests := []struct {
+		name     string
+		balance1 Balance
+		balance2 Balance
+		add      *big.Int
+		sub      *big.Int
+		mul      float64
+		mulRes   *big.Int
+	}{
+		{
+			name:     "basic arithmetic",
+			balance1: NewBalance(big.NewInt(100)),
+			balance2: NewBalance(big.NewInt(50)),
+			add:      big.NewInt(150),
+			sub:      big.NewInt(50),
+			mul:      2.5,
+			mulRes:   big.NewInt(250),
+		},
+		{
+			name:     "zero values",
+			balance1: NewBalance(new(big.Int)),
+			balance2: NewBalance(new(big.Int)),
+			add:      new(big.Int),
+			sub:      new(big.Int),
+			mul:      1.0,
+			mulRes:   new(big.Int),
+		},
+		{
+			name:     "large numbers",
+			balance1: NewBalance(new(big.Int).Mul(big.NewInt(1e18), big.NewInt(100))), // 100 ETH
+			balance2: NewBalance(new(big.Int).Mul(big.NewInt(1e18), big.NewInt(50))),  // 50 ETH
+			add:      new(big.Int).Mul(big.NewInt(1e18), big.NewInt(150)),             // 150 ETH
+			sub:      new(big.Int).Mul(big.NewInt(1e18), big.NewInt(50)),              // 50 ETH
+			mul:      0.5,
+			mulRes:   new(big.Int).Mul(big.NewInt(1e18), big.NewInt(50)), // 50 ETH
+		},
+	}
 
-		if got := a.LessThan(b); got != tt.lt {
-			t.Errorf("LessThan(%v, %v) = %v, want %v", tt.a, tt.b, got, tt.lt)
-		}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Test Add
+			sum := tt.balance1.Add(tt.balance2)
+			assert.Equal(t, 0, sum.Int.Cmp(tt.add), "Add result mismatch")
 
-		if got := a.Equal(b); got != tt.eq {
-			t.Errorf("Equal(%v, %v) = %v, want %v", tt.a, tt.b, got, tt.eq)
-		}
+			// Test Sub
+			diff := tt.balance1.Sub(tt.balance2)
+			assert.Equal(t, 0, diff.Int.Cmp(tt.sub), "Sub result mismatch")
+
+			// Test Mul
+			product := tt.balance1.Mul(tt.mul)
+			assert.Equal(t, 0, product.Int.Cmp(tt.mulRes), "Mul result mismatch")
+		})
 	}
 }
 
-func TestBalance_LogValue(t *testing.T) {
+func TestBalanceLogValue(t *testing.T) {
 	tests := []struct {
-		wei  string // Using string to handle large numbers
-		want string
+		name     string
+		balance  Balance
+		expected string
 	}{
-		{"2000000000000000000", "2 ETH"},   // 2 ETH
-		{"1000000000", "1 Gwei"},           // 1 Gwei
-		{"100", "100 Wei"},                 // 100 Wei
-		{"1500000000000000000", "1.5 ETH"}, // 1.5 ETH
-		{"0", "0 Wei"},                     // 0
+		{
+			name:     "nil balance",
+			balance:  Balance{},
+			expected: "0 ETH",
+		},
+		{
+			name:     "zero balance",
+			balance:  NewBalance(new(big.Int)),
+			expected: "0 Wei",
+		},
+		{
+			name:     "small wei amount",
+			balance:  NewBalance(big.NewInt(100)),
+			expected: "100 Wei",
+		},
+		{
+			name:     "gwei amount",
+			balance:  NewBalance(new(big.Int).Mul(big.NewInt(1), big.NewInt(1e9))),
+			expected: "1 Gwei",
+		},
+		{
+			name:     "eth amount",
+			balance:  NewBalance(new(big.Int).Mul(big.NewInt(1), big.NewInt(1e18))),
+			expected: "1 ETH",
+		},
+		{
+			name:     "large eth amount",
+			balance:  NewBalance(new(big.Int).Mul(big.NewInt(1000), big.NewInt(1e18))),
+			expected: "1000 ETH",
+		},
 	}
 
 	for _, tt := range tests {
-		i := new(big.Int)
-		i.SetString(tt.wei, 10)
-		b := NewBalance(i)
-		got := b.LogValue().String()
-		if got != tt.want {
-			t.Errorf("LogValue() for %v Wei = %v, want %v", tt.wei, got, tt.want)
-		}
-	}
-
-	// Test nil case
-	var nilBalance Balance
-	got := nilBalance.LogValue().String()
-	if got != "0 ETH" {
-		t.Errorf("LogValue() for nil balance = %v, want '0 ETH'", got)
+		t.Run(tt.name, func(t *testing.T) {
+			logValue := tt.balance.LogValue()
+			assert.Equal(t, tt.expected, logValue.String())
+		})
 	}
 }