client/asset/eth: Use gwei in Balance.

client/asset/eth/eth.go

@@ -34,6 +34,9 @@ const (
 	BipID              = 60
 	defaultGasFee      = 8.2e10
 	defaultGasFeeLimit = 2e11
+
+	// Eth balances are floored as gwei, or 1e9 wei.
+	gweiFactor = 1e9
 )
 
 var (
@@ -67,12 +70,13 @@ var (
 	// WalletInfo defines some general information about a Ethereum wallet.
 	WalletInfo = &asset.WalletInfo{
 		Name:              "Ethereum",
-		Units:             "wei",
+		Units:             "gwei",
 		DefaultConfigPath: defaultAppDir, // Incorrect if changed by user?
 		ConfigOpts:        configOpts,
 	}
 	notImplementedErr   = errors.New("not implemented")
 	mainnetContractAddr = common.HexToAddress("")
+	gweiFactorBig       = big.NewInt(gweiFactor)
 )
 
 // Check that Driver implements asset.Driver.
@@ -224,19 +228,23 @@ func (eth *ExchangeWallet) OwnsAddress(address string) (bool, error) {
 
 // Balance returns the total available funds in the account.
 //
-// NOTE: Ethereum balance does not return Immature or Locked values.
+// NOTE: Ethereum Balance does not return Immature or Locked values.
 //
-// TODO: Ethereum balances can easily go over the max value of a uint64.
-// asset.Balance must be changed in a way to accomodate this.
+// NOTE: The eth node returns balances in wei. Those are flored and stored as
+// gwei, or 1e9 wei.
 func (eth *ExchangeWallet) Balance() (*asset.Balance, error) {
 	eth.acctMtx.RLock()
 	defer eth.acctMtx.RUnlock()
-	bigbal, err := eth.node.balance(eth.ctx, eth.acct)
+	bigBal, err := eth.node.balance(eth.ctx, eth.acct)
 	if err != nil {
 		return nil, err
 	}
+	bigBal.Div(bigBal, gweiFactorBig)
+	if !bigBal.IsUint64() {
+		return nil, fmt.Errorf("balance %v gwei is too big for a uint64", bigBal)
+	}
 	bal := &asset.Balance{
-		Available: bigbal.Uint64(),
+		Available: bigBal.Uint64(),
 		// Immature: , How to know?
 		// Locked: , Not lockable?
 	}

client/asset/eth/eth_test.go

@@ -29,6 +29,8 @@ type testNode struct {
 	bestBlkHashErr error
 	blk            *types.Block
 	blkErr         error
+	bal            *big.Int
+	balErr         error
 }
 
 func (n *testNode) connect(ctx context.Context, node *node.Node, addr common.Address) error {
@@ -45,7 +47,7 @@ func (n *testNode) accounts() []*accounts.Account {
 	return nil
 }
 func (n *testNode) balance(ctx context.Context, acct *accounts.Account) (*big.Int, error) {
-	return nil, nil
+	return n.bal, n.balErr
 }
 func (n *testNode) sendToAddr(ctx context.Context, acct *accounts.Account, addr common.Address, amt, gasFee *big.Int) (common.Hash, error) {
 	return common.Hash{}, nil
@@ -177,3 +179,69 @@ func TestCheckForNewBlocks(t *testing.T) {
 
 	}
 }
+
+func TestBalance(t *testing.T) {
+	maxInt := ^uint64(0)
+	maxWei := new(big.Int).SetUint64(maxInt)
+	maxWei.Mul(maxWei, gweiFactorBig)
+	overMaxWei := new(big.Int).Set(maxWei)
+	overMaxWei.Add(overMaxWei, gweiFactorBig)
+	tests := []struct {
+		name    string
+		bal     *big.Int
+		balErr  error
+		wantBal uint64
+		wantErr bool
+	}{{
+		name:    "ok zero",
+		bal:     big.NewInt(0),
+		wantBal: 0,
+	}, {
+		name:    "ok rounded down",
+		bal:     big.NewInt(gweiFactor - 1),
+		wantBal: 0,
+	}, {
+		name:    "ok one",
+		bal:     big.NewInt(gweiFactor),
+		wantBal: 1,
+	}, {
+		name:    "ok max int",
+		bal:     maxWei,
+		wantBal: maxInt,
+	}, {
+		name:    "over max int",
+		bal:     overMaxWei,
+		wantErr: true,
+	}, {
+		name:    "node balance error",
+		bal:     big.NewInt(0),
+		balErr:  errors.New(""),
+		wantErr: true,
+	}}
+
+	for _, test := range tests {
+		ctx, cancel := context.WithCancel(context.Background())
+		node := &testNode{}
+		node.bal = test.bal
+		node.balErr = test.balErr
+		eth := &ExchangeWallet{
+			node: node,
+			ctx:  ctx,
+			log:  tLogger,
+		}
+		bal, err := eth.Balance()
+		cancel()
+		if test.wantErr {
+			if err == nil {
+				t.Fatalf("expected error for test %q", test.name)
+			}
+			continue
+		}
+		if err != nil {
+			t.Fatalf("unexpected error for test %q: %v", test.name, err)
+		}
+		if bal.Available != test.wantBal {
+			t.Fatalf("want available balance %v got %v for test %q", test.wantBal, bal.Available, test.name)
+		}
+	}
+}