Fix the bug when didn't invalidate etherToken contract instance

CHANGELOG.md

@@ -11,6 +11,7 @@ v0.8.0 - TBD
         * `zeroEx.exchange.invalidateContractInstancesAsync`
         * `zeroEx.proxy.invalidateContractInstance`
         * `zeroEx.tokenRegistry.invalidateContractInstance`
+    * Fix the bug when `zeroEx.setProviderAsync` didn't invalidate etherToken contract instance
 
 v0.7.1 - _Jun. 26, 2017_
 ------------------------

src/0x.ts

@@ -172,6 +172,7 @@ export class ZeroEx {
         (this.tokenRegistry as any)._invalidateContractInstance();
         await (this.token as any)._invalidateContractInstancesAsync();
         (this.proxy as any)._invalidateContractInstance();
+        (this.etherToken as any)._invalidateContractInstance();
     }
     /**
      * Get user Ethereum addresses available through the supplied web3 instance available for sending transactions.

src/contract_wrappers/ether_token_wrapper.ts

@@ -64,6 +64,9 @@ export class EtherTokenWrapper extends ContractWrapper {
         const wethContract = await this._getEtherTokenContractAsync();
         return wethContract.address;
     }
+    private _invalidateContractInstance(): void {
+        delete this._etherTokenContractIfExists;
+    }
     private async _getEtherTokenContractAsync(): Promise<EtherTokenContract> {
         if (!_.isUndefined(this._etherTokenContractIfExists)) {
             return this._etherTokenContractIfExists;