feat: mockups/UsingWitPriceFeeds

contracts/mockups/UsingWitPriceFeeds.sol

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity >=0.7.0 <0.9.0;
+pragma experimental ABIEncoderV2;
+
+import "../WitPriceFeeds.sol";
+
+/// @title The UsingWitPriceFeeds contract
+/// @dev Contracts willing to interact with a WitPriceFeeds appliance, freshly updated by a third-party.
+/// @author The Witnet Foundation.
+abstract contract UsingWitPriceFeeds
+    is
+        IWitFeedsEvents,
+        IWitOracleEvents
+{
+    WitPriceFeeds immutable public witPriceFeeds;
+
+    constructor(WitPriceFeeds _witPriceFeeds) {
+        require(
+            address(_witPriceFeeds).code.length > 0
+                && _witPriceFeeds.specs() == type(WitPriceFeeds).interfaceId,
+            "UsingWitPriceFeeds: uncompliant WitPriceFeeds appliance"
+        );
+        witPriceFeeds = _witPriceFeeds;
+    }
+
+    receive() external payable virtual {}
+}

contracts/mockups/UsingWitRandomness.sol

@@ -13,15 +13,15 @@ abstract contract UsingWitRandomness
         IWitOracleEvents,
         IWitRandomnessEvents
 {
-    WitRandomness immutable public witOracleRandomness;
+    WitRandomness immutable public witRandomness;
 
-    constructor(WitRandomness _witOracleRandomness) {
+    constructor(WitRandomness _witRandomness) {
         require(
-            address(_witOracleRandomness).code.length > 0
-                && _witOracleRandomness.specs() == type(WitRandomness).interfaceId,
+            address(_witRandomness).code.length > 0
+                && _witRandomness.specs() == type(WitRandomness).interfaceId,
             "UsingWitRandomness: uncompliant WitRandomness appliance"
         );
-        witOracleRandomness = _witOracleRandomness;
+        witRandomness = _witRandomness;
     }
 
     receive() external payable virtual {}