accounts/abi/bind/backend, internal/ethapi: recap gas limit with balance (#21043)

* accounts/abi/bind/backend, internal/ethapi: recap gas limit with balance

* accounts, internal: address comment and fix lint

* accounts, internal: extend log message

* tiny nits to format hexutil.Big and nil properly

Co-authored-by: Péter Szilágyi <peterke@gmail.com>

accounts/abi/bind/backends/simulated_test.go

@@ -466,6 +466,73 @@ func TestSimulatedBackend_EstimateGas(t *testing.T) {
 	}
 }
 
+func TestSimulatedBackend_EstimateGasWithPrice(t *testing.T) {
+	key, _ := crypto.GenerateKey()
+	addr := crypto.PubkeyToAddress(key.PublicKey)
+
+	sim := NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(params.Ether*2 + 2e17)}}, 10000000)
+	defer sim.Close()
+
+	receipant := common.HexToAddress("deadbeef")
+	var cases = []struct {
+		name        string
+		message     ethereum.CallMsg
+		expect      uint64
+		expectError error
+	}{
+		{"EstimateWithoutPrice", ethereum.CallMsg{
+			From:     addr,
+			To:       &receipant,
+			Gas:      0,
+			GasPrice: big.NewInt(0),
+			Value:    big.NewInt(1000),
+			Data:     nil,
+		}, 21000, nil},
+
+		{"EstimateWithPrice", ethereum.CallMsg{
+			From:     addr,
+			To:       &receipant,
+			Gas:      0,
+			GasPrice: big.NewInt(1000),
+			Value:    big.NewInt(1000),
+			Data:     nil,
+		}, 21000, nil},
+
+		{"EstimateWithVeryHighPrice", ethereum.CallMsg{
+			From:     addr,
+			To:       &receipant,
+			Gas:      0,
+			GasPrice: big.NewInt(1e14), // gascost = 2.1ether
+			Value:    big.NewInt(1e17), // the remaining balance for fee is 2.1ether
+			Data:     nil,
+		}, 21000, nil},
+
+		{"EstimateWithSuperhighPrice", ethereum.CallMsg{
+			From:     addr,
+			To:       &receipant,
+			Gas:      0,
+			GasPrice: big.NewInt(2e14), // gascost = 4.2ether
+			Value:    big.NewInt(1000),
+			Data:     nil,
+		}, 21000, errors.New("gas required exceeds allowance (10999)")}, // 10999=(2.2ether-1000wei)/(2e14)
+	}
+	for _, c := range cases {
+		got, err := sim.EstimateGas(context.Background(), c.message)
+		if c.expectError != nil {
+			if err == nil {
+				t.Fatalf("Expect error, got nil")
+			}
+			if c.expectError.Error() != err.Error() {
+				t.Fatalf("Expect error, want %v, got %v", c.expectError, err)
+			}
+			continue
+		}
+		if got != c.expect {
+			t.Fatalf("Gas estimation mismatch, want %d, got %d", c.expect, got)
+		}
+	}
+}
+
 func TestSimulatedBackend_HeaderByHash(t *testing.T) {
 	testAddr := crypto.PubkeyToAddress(testKey.PublicKey)