change estimate gas request and improve formatter

Author: Alex Vlasov

web3swift/Transaction/Classes/EthereumTransaction.swift

@@ -317,7 +317,10 @@ public struct EthereumTransaction: CustomStringConvertible {
         var request = JSONRPCrequest()
         request.method = method
         guard let from = options?.from else {return nil}
-        guard let txParams = transaction.encodeAsDictionary(from: from) else {return nil}
+        guard var txParams = transaction.encodeAsDictionary(from: from) else {return nil}
+        if options?.gasLimit == nil {
+            txParams.gas = nil
+        }
         var params = [txParams] as Array<Encodable>
         if method.requiredNumOfParameters == 2 && onBlock != nil {
             params.append(onBlock as Encodable)

web3swift/Web3/Classes/Web3+Eth.swift

@@ -293,7 +293,8 @@ extension web3.Eth {
     }
 
     public func estimateGas(_ transaction: EthereumTransaction, options: Web3Options?, onBlock: String = "latest") -> Result<BigUInt, Web3Error> {
-        let mergedOptions = Web3Options.merge(self.options, with: options)
+        var mergedOptions = Web3Options.merge(self.options, with: options)
+        mergedOptions?.gasLimit = nil // use gas limit of the previous block
         guard let request = EthereumTransaction.createRequest(method: JSONRPCmethod.estimateGas, transaction: transaction, onBlock: onBlock, options: mergedOptions) else {
             return Result.failure(Web3Error.inputError("Transaction serialization failed"))
         }

web3swift/Web3/Classes/Web3+Utils.swift

@@ -169,6 +169,9 @@ extension Web3.Utils {
     }
 
     public static func formatToPrecision(_ bigNumber: BigUInt, numberDecimals: Int = 18, formattingDecimals: Int = 4, decimalSeparator: String = ".", fallbackToScientific: Bool = false) -> String? {
+        if bigNumber == 0 {
+            return "0"
+        }
         let unitDecimals = numberDecimals
         var toDecimals = formattingDecimals
         if unitDecimals < toDecimals {
@@ -179,17 +182,21 @@ extension Web3.Utils {
         let fullRemainder = String(remainder);
         let fullPaddedRemainder = fullRemainder.leftPadding(toLength: unitDecimals, withPad: "0")
         let remainderPadded = fullPaddedRemainder[0..<toDecimals]
-        if remainderPadded == String(repeating: "0", count: toDecimals) && quotient == 0 {
-            var firstDigit = 0
-            for char in fullPaddedRemainder {
-                if (char == "0") {
-                    firstDigit = firstDigit + 1;
-                } else {
-                    firstDigit = firstDigit + 1;
-                    break
+        if remainderPadded == String(repeating: "0", count: toDecimals) {
+            if quotient != 0 {
+                return String(quotient)
+            } else if fallbackToScientific {
+                var firstDigit = 0
+                for char in fullPaddedRemainder {
+                    if (char == "0") {
+                        firstDigit = firstDigit + 1;
+                    } else {
+                        firstDigit = firstDigit + 1;
+                        break
+                    }
                 }
+                return fullRemainder + "e-" + String(firstDigit)
             }
-            return fullRemainder + "e-" + String(firstDigit)
         }
         if (toDecimals == 0) {
             return String(quotient)

web3swiftTests/web3swiftTests.swift

@@ -2213,6 +2213,14 @@ class web3swiftTests: XCTestCase {
         let keystoreManager = KeystoreManager([tempKeystore!])
         web3.addKeystoreManager(keystoreManager)
         let intermediate = web3.eth.sendERC20tokensWithNaturalUnits(tokenAddress:contractAddress, from: coldWalletAddress, to: coldWalletAddress, amount: "1.0")
+        let gasEstimate = intermediate!.estimateGas(options: nil)
+        switch gasEstimate {
+        case .success(let result):
+            print(result)
+        case .failure(let error):
+            print(error)
+            XCTFail()
+        }
         let bkxBalanceSend = intermediate!.call(options: nil)
         switch bkxBalanceSend {
         case .success(let result):
@@ -2267,6 +2275,12 @@ class web3swiftTests: XCTestCase {
         XCTAssert(formatted == "-1e-18")
     }
 
+    func testNumberFormattingUtil6() {
+        let balance = BigInt("0")!
+        let formatted = Web3.Utils.formatToPrecision(balance, numberDecimals: 18, formattingDecimals: 9, decimalSeparator: ",")
+        XCTAssert(formatted == "0")
+    }
+    
     func testPerformanceExample() {
         // This is an example of a performance test case.
         self.measure {