Add PerpV2 test fixture

contracts/mocks/external/ChainlinkAggregatorMock.sol

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+/*
+    Copyright 2020 Set Labs Inc.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+    SPDX-License-Identifier: Apache License, Version 2.0
+*/
+
+pragma solidity 0.6.10;
+
+/**
+ * Mock ChainlinkAggregator that can be passed to any contract that consumes these.
+ * This contract was implemented for the PerpV2 fixture as a substitute for the smock-ed
+ * aggregators they use in their own test suite.
+ */
+contract ChainlinkAggregatorMock {
+    int256 public latestAnswer;
+    uint80 public latestRoundId;
+    uint256 public latestStartedAt;
+    uint256 public latestUpdatedAt;
+    uint80 public latestAnsweredInRound;
+    uint8 public decimals;
+
+    // Perp sets this to `6` in their fixtures...
+    constructor(uint8 _decimals) public {
+        decimals = _decimals;
+    }
+
+    /**
+     * Typical usage for setting the BaseToken oracle to 100 is:
+     *
+     * ```
+     *  await mockAggregator.setLatestAnswer(ethers.utils.parseUnits("100", 6));
+     * ```
+     */
+    function setLatestAnswer(int256 _latestAnswer) public {
+        latestAnswer = _latestAnswer;
+    }
+
+    /**
+     * Typical usage for setting the BaseToken oracle to 100 is:
+     *
+     * ```
+     *  await mockAggregator.setRoundData(0, ethers.utils.parseUnits("100", 6),0,0,0);
+     * ```
+     */
+    function setRoundData(
+        uint80 _roundId,
+        int256 _answer,
+        uint256 _startedAt,
+        uint256 _updatedAt,
+        uint80 _answeredInRound
+    )
+        public
+    {
+        latestRoundId = _roundId;
+        latestAnswer = _answer;
+        latestStartedAt = _startedAt;
+        latestUpdatedAt = _updatedAt;
+        latestAnsweredInRound = _answeredInRound;
+    }
+
+    // Consumed by PerpV2.ChainlinkPriceFeed
+    function getRoundData(uint80 /* _roundId */)
+        public
+        view
+        returns (
+            uint80 roundId,
+            int256 answer,
+            uint256 startedAt,
+            uint256 updatedAt,
+            uint80 answeredInRound
+        )
+    {
+        return (
+            latestRoundId,
+            latestAnswer,
+            latestStartedAt,
+            latestUpdatedAt,
+            latestAnsweredInRound
+        );
+    }
+
+    // Consumed by PerpV2.ChainlinkPriceFeed
+    function latestRoundData()
+        public
+        view
+        returns (
+            uint80 roundId,
+            int256 answer,
+            uint256 startedAt,
+            uint256 updatedAt,
+            uint80 answeredInRound
+        )
+    {
+        return (
+            latestRoundId,
+            latestAnswer,
+            latestStartedAt,
+            latestUpdatedAt,
+            latestAnsweredInRound
+        );
+    }
+}
+