Merge pull request #28 from propeller-heads/lp/balancer-fixes

Fix balancer adapter

evm/src/balancer-v2/BalancerV2SwapAdapter.sol

@@ -100,27 +100,19 @@ contract BalancerV2SwapAdapter is ISwapAdapter {
         sellAmount = uint256(assetDeltas[0]);
     }
 
-    function priceBatch(
+    function price(
         bytes32 poolId,
         address sellToken,
         address buyToken,
         uint256[] memory specifiedAmounts
     ) external returns (Fraction[] memory calculatedPrices) {
+        calculatedPrices = new Fraction[](specifiedAmounts.length);
         for (uint256 i = 0; i < specifiedAmounts.length; i++) {
             calculatedPrices[i] =
                 priceSingle(poolId, sellToken, buyToken, specifiedAmounts[i]);
         }
     }
 
-    function price(bytes32, address, address, uint256[] memory)
-        external
-        pure
-        override
-        returns (Fraction[] memory)
-    {
-        revert NotImplemented("BalancerV2SwapAdapter.price");
-    }
-
     function swap(
         bytes32 poolId,
         address sellToken,
@@ -196,9 +188,10 @@ contract BalancerV2SwapAdapter is ISwapAdapter {
         override
         returns (Capability[] memory capabilities)
     {
-        capabilities = new Capability[](2);
+        capabilities = new Capability[](3);
         capabilities[0] = Capability.SellOrder;
         capabilities[1] = Capability.BuyOrder;
+        capabilities[2] = Capability.PriceFunction;
     }
 
     function getTokens(bytes32 poolId)

evm/src/interfaces/ISwapAdapter.sol

@@ -37,7 +37,7 @@ interface ISwapAdapter is ISwapAdapterTypes {
         address sellToken,
         address buyToken,
         uint256[] memory specifiedAmounts
-    ) external view returns (Fraction[] memory prices);
+    ) external returns (Fraction[] memory prices);
 
     /**
      * @notice Simulates swapping tokens on a given pool.

evm/test/BalancerV2SwapAdapter.t.sol

@@ -40,14 +40,16 @@ contract BalancerV2SwapAdapterTest is Test, ISwapAdapterTypes {
 
     function testPrice() public {
         uint256[] memory amounts = new uint256[](2);
-        amounts[0] = 100;
-        amounts[1] = 200;
-        vm.expectRevert(
-            abi.encodeWithSelector(
-                NotImplemented.selector, "BalancerV2SwapAdapter.price"
-            )
-        );
-        adapter.price(B_80BAL_20WETH_POOL_ID, BAL, WETH, amounts);
+        amounts[0] = 1e18;
+        amounts[1] = 2e18;
+
+        Fraction[] memory prices =
+            adapter.price(B_80BAL_20WETH_POOL_ID, BAL, WETH, amounts);
+
+        for (uint256 i = 0; i < prices.length; i++) {
+            assertGt(prices[i].numerator, 0);
+            assertGt(prices[i].denominator, 0);
+        }
     }
 
     function testPriceSingleFuzz() public {
@@ -206,9 +208,10 @@ contract BalancerV2SwapAdapterTest is Test, ISwapAdapterTypes {
     {
         Capability[] memory res = adapter.getCapabilities(pool, t0, t1);
 
-        assertEq(res.length, 2);
+        assertEq(res.length, 3);
         assertEq(uint256(res[0]), uint256(Capability.SellOrder));
         assertEq(uint256(res[1]), uint256(Capability.BuyOrder));
+        assertEq(uint256(res[2]), uint256(Capability.PriceFunction));
     }
 
     function testGetTokens() public {