Add zeroEx.etherToken.getContractAddressifExists

packages/0x.js/src/contract_wrappers/contract_wrapper.ts

@@ -34,7 +34,7 @@ const CONTRACT_NAME_TO_NOT_FOUND_ERROR: {
 
 export class ContractWrapper {
     protected _web3Wrapper: Web3Wrapper;
-    private _networkId: number;
+    protected _networkId: number;
     private _abiDecoder?: AbiDecoder;
     private _blockAndLogStreamerIfExists: BlockAndLogStreamer | undefined;
     private _blockAndLogStreamInterval: NodeJS.Timer;

packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts

@@ -163,6 +163,15 @@ export class EtherTokenWrapper extends ContractWrapper {
     public unsubscribeAll(): void {
         super.unsubscribeAll();
     }
+    /**
+     * Retrieves the Ethereum address of the EtherToken contract deployed on the network
+     * that the user-passed web3 provider is connected to. If it's an unknown private network - undefined is returned.
+     * @returns The Ethereum address of the EtherToken contract or undefined.
+     */
+    public getContractAddressIfExists(): string | undefined {
+        const contractAddress = artifacts.EtherTokenArtifact.networks[this._networkId].address;
+        return contractAddress;
+    }
     private _invalidateContractInstance(): void {
         this.unsubscribeAll();
         this._etherTokenContractsByAddress = {};

packages/0x.js/test/ether_token_wrapper_test.ts

@@ -61,7 +61,7 @@ describe('EtherTokenWrapper', () => {
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         addressWithETH = userAddresses[0];
-        wethContractAddress = (zeroEx.etherToken as any)._getContractAddress(artifacts.EtherTokenArtifact);
+        wethContractAddress = zeroEx.etherToken.getContractAddressIfExists() as string;
         depositWeiAmount = (zeroEx as any)._web3Wrapper.toWei(new BigNumber(5));
         decimalPlaces = 7;
         addressWithoutFunds = userAddresses[1];