fix: mStable USD Sampler and Mixin fix (#238)

* fix: mStable USD Sampler and Mixin fix

* chore: adding mBTC (mStable) pool

* fix linter

contracts/zero-ex/contracts/src/transformers/bridges/mixins/MixinMStable.sol

@@ -31,6 +31,7 @@ interface IMStable {
         IERC20TokenV06 sellToken,
         IERC20TokenV06 buyToken,
         uint256 sellAmount,
+        uint256 minBoughtAmount,
         address recipient
     )
         external
@@ -59,6 +60,8 @@ contract MixinMStable {
             sellToken,
             buyToken,
             sellAmount,
+            // Minimum buy amount.
+            1,
             address(this)
         );
     }

packages/asset-swapper/contracts/src/MStableSampler.sol

@@ -49,6 +49,7 @@ contract MStableSampler is
         view
         returns (uint256[] memory makerTokenAmounts)
     {
+        _assertValidPair(makerToken, takerToken);
         // Initialize array of maker token amounts.
         uint256 numSamples = takerTokenAmounts.length;
         makerTokenAmounts = new uint256[](numSamples);
@@ -58,7 +59,7 @@ contract MStableSampler is
                 IMStable(router).getSwapOutput
                     {gas: DEFAULT_CALL_GAS}
                     (takerToken, makerToken, takerTokenAmounts[i])
-                returns (bool, string memory, uint256 amount)
+                returns (uint256 amount)
             {
                 makerTokenAmounts[i] = amount;
                 // Break early if there are 0 amounts

packages/asset-swapper/contracts/src/interfaces/IMStable.sol

@@ -29,5 +29,5 @@ interface IMStable {
     )
         external
         view
-        returns (bool, string memory, uint256 output);
+        returns (uint256 swapOutput);
 }

packages/asset-swapper/src/utils/market_operation_utils/bridge_source_utils.ts

@@ -17,6 +17,7 @@ import {
     KYBER_DMM_ROUTER_BY_CHAIN_ID,
     MAX_DODOV2_POOLS_QUERIED,
     MAX_KYBER_RESERVES_QUERIED,
+    MSTABLE_POOLS_BY_CHAIN_ID,
     NERVE_BSC_INFOS,
     NULL_ADDRESS,
     PANCAKESWAP_ROUTER_BY_CHAIN_ID,
@@ -86,6 +87,16 @@ export function getComponentForPair(chainId: ChainId, takerToken: string, makerT
         .map(i => i.poolAddress);
 }
 
+// tslint:disable completed-docs
+export function getMStableForPair(chainId: ChainId, takerToken: string, makerToken: string): string[] {
+    if (chainId !== ChainId.Mainnet) {
+        return [];
+    }
+    return Object.values(MSTABLE_POOLS_BY_CHAIN_ID[chainId])
+        .filter(c => [makerToken, takerToken].every(t => c.tokens.includes(t)))
+        .map(i => i.poolAddress);
+}
+
 // tslint:disable completed-docs
 export function getCurveInfosForPair(chainId: ChainId, takerToken: string, makerToken: string): CurveInfo[] {
     if (chainId !== ChainId.Mainnet) {
@@ -221,13 +232,15 @@ export function getShellLikeInfosForPair(
     chainId: ChainId,
     takerToken: string,
     makerToken: string,
-    source: ERC20BridgeSource.Shell | ERC20BridgeSource.Component,
+    source: ERC20BridgeSource.Shell | ERC20BridgeSource.Component | ERC20BridgeSource.MStable,
 ): string[] {
     switch (source) {
         case ERC20BridgeSource.Shell:
             return getShellsForPair(chainId, takerToken, makerToken);
         case ERC20BridgeSource.Component:
             return getComponentForPair(chainId, takerToken, makerToken);
+        case ERC20BridgeSource.MStable:
+            return getMStableForPair(chainId, takerToken, makerToken);
         default:
             throw new Error(`Unknown Shell like source ${source}`);
     }

packages/asset-swapper/src/utils/market_operation_utils/constants.ts

@@ -907,11 +907,29 @@ export const LINKSWAP_ROUTER_BY_CHAIN_ID = valueByChainId<string>(
     NULL_ADDRESS,
 );
 
-export const MSTABLE_ROUTER_BY_CHAIN_ID = valueByChainId<string>(
+export const MSTABLE_POOLS_BY_CHAIN_ID = valueByChainId(
     {
-        [ChainId.Mainnet]: '0xe2f2a5c287993345a840db3b0845fbc70f5935a5',
+        [ChainId.Mainnet]: {
+            mUSD: {
+                poolAddress: '0xe2f2a5c287993345a840db3b0845fbc70f5935a5',
+                tokens: [MAINNET_TOKENS.DAI, MAINNET_TOKENS.USDC, MAINNET_TOKENS.USDT],
+            },
+            mBTC: {
+                poolAddress: '0x945facb997494cc2570096c74b5f66a3507330a1',
+                tokens: [MAINNET_TOKENS.WBTC, MAINNET_TOKENS.RenBTC, MAINNET_TOKENS.sBTC],
+            },
+        },
+    },
+    {
+        mUSD: {
+            poolAddress: NULL_ADDRESS,
+            tokens: [] as string[],
+        },
+        mBTC: {
+            poolAddress: NULL_ADDRESS,
+            tokens: [] as string[],
+        },
     },
-    NULL_ADDRESS,
 );
 
 export const OASIS_ROUTER_BY_CHAIN_ID = valueByChainId<string>(
@@ -1208,7 +1226,7 @@ export const DEFAULT_GAS_SCHEDULE: Required<FeeSchedule> = {
     [ERC20BridgeSource.Balancer]: () => 120e3,
     [ERC20BridgeSource.BalancerV2]: () => 100e3,
     [ERC20BridgeSource.Cream]: () => 120e3,
-    [ERC20BridgeSource.MStable]: () => 700e3,
+    [ERC20BridgeSource.MStable]: () => 200e3,
     [ERC20BridgeSource.MakerPsm]: (fillData?: FillData) => {
         const psmFillData = fillData as MakerPsmFillData;
         return psmFillData.takerToken === psmFillData.gemTokenAddress ? 210e3 : 290e3;

packages/asset-swapper/src/utils/market_operation_utils/sampler_operations.ts

@@ -29,7 +29,6 @@ import {
     MAKER_PSM_INFO_BY_CHAIN_ID,
     MAX_UINT256,
     MOONISWAP_REGISTRIES_BY_CHAIN_ID,
-    MSTABLE_ROUTER_BY_CHAIN_ID,
     NATIVE_FEE_TOKEN_BY_CHAIN_ID,
     NULL_ADDRESS,
     NULL_BYTES,
@@ -1204,14 +1203,9 @@ export class SamplerOperations {
                                 ),
                             );
                         case ERC20BridgeSource.MStable:
-                            return isValidAddress(MSTABLE_ROUTER_BY_CHAIN_ID[this.chainId])
+                            return getShellLikeInfosForPair(this.chainId, takerToken, makerToken, source).map(pool =>
-                                ? this.getMStableSellQuotes(
+                                this.getMStableSellQuotes(pool, makerToken, takerToken, takerFillAmounts),
-                                      MSTABLE_ROUTER_BY_CHAIN_ID[this.chainId],
+                            );
-                                      makerToken,
-                                      takerToken,
-                                      takerFillAmounts,
-                                  )
-                                : [];
                         case ERC20BridgeSource.Mooniswap:
                             return [
                                 ...MOONISWAP_REGISTRIES_BY_CHAIN_ID[this.chainId]
@@ -1456,14 +1450,9 @@ export class SamplerOperations {
                                 ),
                             );
                         case ERC20BridgeSource.MStable:
-                            return isValidAddress(MSTABLE_ROUTER_BY_CHAIN_ID[this.chainId])
+                            return getShellLikeInfosForPair(this.chainId, takerToken, makerToken, source).map(pool =>
-                                ? this.getMStableBuyQuotes(
+                                this.getMStableBuyQuotes(pool, makerToken, takerToken, makerFillAmounts),
-                                      MSTABLE_ROUTER_BY_CHAIN_ID[this.chainId],
+                            );
-                                      makerToken,
-                                      takerToken,
-                                      makerFillAmounts,
-                                  )
-                                : [];
                         case ERC20BridgeSource.Mooniswap:
                             return [
                                 ...MOONISWAP_REGISTRIES_BY_CHAIN_ID[this.chainId]