Merge pull request web3swift-team#324 from linen-app/gas_estimate_fix

Gas estimate fix

Author: AnnaYatsun1

Sources/web3swift/Promises/Promise+Web3+Eth+EstimateGas.swift

@@ -24,7 +24,22 @@ extension web3.Eth {
                     }
                     throw Web3Error.nodeError(desc: "Invalid value from Ethereum node")
                 }
-                return value
+                
+                if let policy = transactionOptions?.gasLimit {
+                    switch policy {
+                    case .automatic:
+                        return value
+                    case .limited(let limitValue):
+                        return limitValue < value ? limitValue: value
+                    case .manual(let exactValue):
+                        return exactValue
+                    case .withMargin:
+                        // MARK: - update value according margin
+                        return value
+                    }
+                } else {
+                    return value
+                }
             }
         } catch {
             let returnPromise = Promise<BigUInt>.pending()

Sources/web3swift/Web3/Web3+MutatingTransaction.swift

@@ -72,8 +72,21 @@ public class WriteTransaction: ReadTransaction {
             optionsForGasEstimation.from = mergedOptions.from
             optionsForGasEstimation.to = mergedOptions.to
             optionsForGasEstimation.value = mergedOptions.value
+            optionsForGasEstimation.gasLimit = mergedOptions.gasLimit
             optionsForGasEstimation.callOnBlock = mergedOptions.callOnBlock
-            let gasEstimatePromise : Promise<BigUInt> = self.web3.eth.estimateGasPromise(assembledTransaction, transactionOptions: optionsForGasEstimation)
+            
+            // assemble promise for gasLimit
+            var gasEstimatePromise: Promise<BigUInt>? = nil
+            guard let gasLimitPolicy = mergedOptions.gasLimit else {
+                seal.reject(Web3Error.inputError(desc: "No gasLimit policy provided"))
+                return
+            }
+            switch gasLimitPolicy {
+            case .automatic, .withMargin, .limited:
+                gasEstimatePromise = self.web3.eth.estimateGasPromise(assembledTransaction, transactionOptions: optionsForGasEstimation)
+            case .manual(let gasLimit):
+                gasEstimatePromise = Promise<BigUInt>.value(gasLimit)
+            }
 
             // assemble promise for nonce
             var getNoncePromise: Promise<BigUInt>?
@@ -90,9 +103,20 @@ public class WriteTransaction: ReadTransaction {
                 getNoncePromise = Promise<BigUInt>.value(nonce)
             }
 
-            let gasPricePromise : Promise<BigUInt> = self.web3.eth.getGasPricePromise()
-            var promisesToFulfill: [Promise<BigUInt>] = [getNoncePromise!, gasPricePromise, gasPricePromise]
-            when(resolved: getNoncePromise!, gasEstimatePromise, gasPricePromise).map(on: queue, { (results:[PromiseResult<BigUInt>]) throws -> EthereumTransaction in
+            // assemble promise for gasPrice
+            var gasPricePromise: Promise<BigUInt>? = nil
+            guard let gasPricePolicy = mergedOptions.gasPrice else {
+                seal.reject(Web3Error.inputError(desc: "No gasPrice policy provided"))
+                return
+            }
+            switch gasPricePolicy {
+            case .automatic, .withMargin:
+                gasPricePromise = self.web3.eth.getGasPricePromise()
+            case .manual(let gasPrice):
+                gasPricePromise = Promise<BigUInt>.value(gasPrice)
+            }
+            var promisesToFulfill: [Promise<BigUInt>] = [getNoncePromise!, gasPricePromise!, gasEstimatePromise!]
+            when(resolved: getNoncePromise!, gasEstimatePromise!, gasPricePromise!).map(on: queue, { (results:[PromiseResult<BigUInt>]) throws -> EthereumTransaction in
 
                 promisesToFulfill.removeAll()
                 guard case .fulfilled(let nonce) = results[0] else {