Allow simulation of transactions (#232)

* Allow simulation of transactions

* 0.4.8

* always simulate

* fix

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@dydxprotocol/solo",
-  "version": "0.4.7",
+  "version": "0.4.8",
   "description": "Ethereum Smart Contracts and TypeScript library used for the dYdX Solo-Margin Trading Protocol",
   "main": "dist/js/src/index.js",
   "types": "dist/types/src/types.d.ts",

src/lib/Contracts.ts

@@ -400,12 +400,12 @@ export class Contracts {
       txOptions.gasPrice = this.defaultGasPrice;
     }
 
-    if (!options.gas) {
-      if (this.defaultGas) {
+    if (confirmationType === ConfirmationType.Simulate || !options.gas) {
+      let gasEstimate: number;
+
+      if (this.defaultGas && confirmationType !== ConfirmationType.Simulate) {
         txOptions.gas = this.defaultGas;
       } else {
-        let gasEstimate: number;
-
         try {
           gasEstimate = await method.estimateGas(txOptions);
         } catch (error) {
@@ -420,6 +420,10 @@ export class Contracts {
         const totalGas: number = Math.floor(gasEstimate * multiplier);
         txOptions.gas = totalGas < this.blockGasLimit ? totalGas : this.blockGasLimit;
       }
+
+      if (confirmationType === ConfirmationType.Simulate) {
+        return { gasEstimate, gas: Number(txOptions.gas) };
+      }
     }
 
     if (txOptions.value) {

src/modules/operate/AccountOperation.ts

@@ -22,6 +22,7 @@ import {
   Amount,
   Integer,
   AccountOperationOptions,
+  ConfirmationType,
   address,
 } from '../../types';
 import { toBytes } from '../../lib/BytesHelper';
@@ -209,7 +210,9 @@ export class AccountOperation {
       throw new Error('No actions have been added to operation');
     }
 
-    this.committed = true;
+    if (options && options.confirmationType !== ConfirmationType.Simulate) {
+      this.committed = true;
+    }
 
     try {
       let method: TransactionObject<void>;
@@ -223,7 +226,7 @@ export class AccountOperation {
         method = this.contracts.payableProxy.methods.operate(
           this.accounts,
           this.actions,
-          this.sendEthTo || options.from || this.contracts.payableProxy.options.from,
+          this.sendEthTo || (options && options.from) || this.contracts.payableProxy.options.from,
         );
       }
 

src/types.ts

@@ -29,6 +29,7 @@ export enum ConfirmationType {
   Hash = 0,
   Confirmed = 1,
   Both = 2,
+  Simulate = 3,
 }
 
 export interface SoloOptions {
@@ -64,7 +65,7 @@ export interface LogParsingOptions {
 }
 
 export interface TxResult {
-  transactionHash: string;
+  transactionHash?: string;
   transactionIndex?: number;
   blockHash?: string;
   blockNumber?: number;
@@ -79,6 +80,8 @@ export interface TxResult {
   };
   status?: boolean;
   confirmation?: Promise<TransactionReceipt>;
+  gasEstimate?: number;
+  gas?: number;
 }
 
 export enum AmountDenomination {