Merge pull request #119 from matter-labs/estimateGasFix

fixed estimate gas problem

Author: TonioMacaronio

web3swift/Web3/Classes/Web3+ReadingTransaction.swift

@@ -71,6 +71,17 @@ public class ReadTransaction {
             optionsForGasEstimation.from = mergedOptions.from
             optionsForGasEstimation.to = mergedOptions.to
             optionsForGasEstimation.value = mergedOptions.value
+            
+            // MARK: - Fixing estimate gas problem: gas price param shouldn't be nil
+            if let gasPricePolicy = mergedOptions.gasPrice {
+                switch gasPricePolicy {
+                case .manual( _):
+                    optionsForGasEstimation.gasPrice = gasPricePolicy
+                default:
+                    optionsForGasEstimation.gasPrice = .manual(1) // 1 wei to fix wrong estimating gas problem
+                }
+            }
+            
             optionsForGasEstimation.callOnBlock = mergedOptions.callOnBlock
             let promise = self.web3.eth.estimateGasPromise(assembledTransaction, transactionOptions: optionsForGasEstimation)
             promise.done(on: queue) {(estimate: BigUInt) in

web3swift/Web3/Classes/Web3+Utils.swift

@@ -66,6 +66,11 @@ extension Web3.Utils {
         }
     }
 
+    // Precoded API for testing estimate gas fix
+    public static var estimateGasTestABI = """
+[{"constant":true,"inputs":[],"name":"a","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"foo","type":"uint256"}],"name":"test","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"b","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}]
+"""
+    
     /// Precoded "cold wallet" (private key controlled) address. Basically - only a payable fallback function.
     public static var coldWalletABI = "[{\"payable\":true,\"type\":\"fallback\"}]"
 

web3swiftTests/web3swift_promises_Tests.swift

@@ -46,15 +46,61 @@ class web3swift_promises_Tests: XCTestCase {
             guard let writeTX = contract?.write("fallback") else {return XCTFail()}
             writeTX.transactionOptions.from = tempKeystore!.addresses?.first
             writeTX.transactionOptions.value = BigUInt("1.0", .eth)
-            let esimate = try writeTX.estimateGasPromise().wait()
-            print(esimate)
-            XCTAssert(esimate == 21000)
+            let estimate = try writeTX.estimateGasPromise().wait()
+            print(estimate)
+            XCTAssert(estimate == 21000)
         } catch{
             print(error)
             XCTFail()
         }
     }
 
+    func testEstimateGasFixPromise() {
+        do {
+            let web3 = Web3.InfuraMainnetWeb3()
+            let tempKeystore = try! EthereumKeystoreV3(password: "")
+            let keystoreManager = KeystoreManager([tempKeystore!])
+            web3.addKeystoreManager(keystoreManager)
+            
+            guard let contractAddress = EthereumAddress("0x28a958cD020efeA3734a0bb36DDdc5F9B872cEa8"),
+                let contract = web3.contract(Web3.Utils.estimateGasTestABI,
+                                             at: contractAddress,
+                                             abiVersion: 2) else {
+                    return
+            }
+            
+            var options = TransactionOptions.defaultOptions
+            let fromAddress = tempKeystore!.addresses?.first
+            options.from = fromAddress
+            
+            let amount1 = Web3.Utils.parseToBigUInt("0.000000000000000001", units: .eth) // 1 wei
+            
+            guard let tx1 = contract.write("test",
+                                           parameters: [amount1] as [AnyObject],
+                                           extraData: Data(),
+                                           transactionOptions: options) else {
+                                            return
+            }
+            let estimate1 = try tx1.estimateGasPromise().wait()
+            print(estimate1)
+            
+            let amount2 = Web3.Utils.parseToBigUInt("0.00000005", units: .eth) // 50 gwei
+
+            guard let tx2 = contract.write("test",
+                                           parameters: [amount2] as [AnyObject],
+                                           extraData: Data(),
+                                           transactionOptions: options) else {
+                                            return
+            }
+            let estimate2 = try tx2.estimateGasPromise().wait()
+            print(estimate2)
+            XCTAssert(estimate2 - estimate1 <= 22000)
+        } catch {
+            print(error)
+            XCTFail()
+        }
+    }
+    
 //    func testSendETHPromise() {
 //        do {
 //            guard let keystoreData = getKeystoreData() else {return}