add e2e test for flatten task

e2e/.gitignore

@@ -1,2 +1,3 @@
 # All e2e test temporary folders
 projects-initialization-tests-*
+fixture-projects-run-*

e2e/fixture-projects/flatten/contracts/A.sol

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+/* SPDX-License-Identifier: MIT */
+
+pragma abicoder v2;
+pragma solidity ^0.8.19;
+
+import "./B.sol";
+
+contract A {
+    uint256 private storedData;
+
+    function set(uint256 value) public {
+        storedData = value;
+    }
+
+    function get() public view returns (uint256) {
+        return storedData;
+    }
+}

e2e/fixture-projects/flatten/contracts/B.sol

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+// SPDX-License-Identifier: MPL-2.0
+
+pragma solidity ^0.8.19;
+
+import "./C.sol";
+
+contract B {
+    uint public x;
+
+    function inc() public {
+        x++;
+    }
+}

e2e/fixture-projects/flatten/contracts/C.sol

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+pragma solidity ^0.8.19;
+
+contract C {}

e2e/fixture-projects/flatten/contracts/Lock.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.19;
+
+// Uncomment this line to use console.log
+// import "hardhat/console.sol";
+
+contract Lock {
+    uint public unlockTime;
+    address payable public owner;
+
+    event Withdrawal(uint amount, uint when);
+
+    constructor(uint _unlockTime) payable {
+        require(
+            block.timestamp < _unlockTime,
+            "Unlock time should be in the future"
+        );
+
+        unlockTime = _unlockTime;
+        owner = payable(msg.sender);
+    }
+
+    function withdraw() public {
+        // Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
+        // console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);
+
+        require(block.timestamp >= unlockTime, "You can't withdraw yet");
+        require(msg.sender == owner, "You aren't the owner");
+
+        emit Withdrawal(address(this).balance, block.timestamp);
+
+        owner.transfer(address(this).balance);
+    }
+}

e2e/fixture-projects/flatten/flatten_all_files.txt

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+// Sources flattened with hardhat v2.19.2 https://hardhat.org
+
+// SPDX-License-Identifier: MIT AND MPL-2.0 AND UNLICENSED
+
+pragma abicoder v2;
+
+// File contracts/C.sol
+
+pragma solidity ^0.8.19;
+
+contract C {}
+
+
+// File contracts/B.sol
+
+// Original license: SPDX_License_Identifier: MPL-2.0
+
+pragma solidity ^0.8.19;
+
+contract B {
+    uint public x;
+
+    function inc() public {
+        x++;
+    }
+}
+
+
+// File contracts/A.sol
+
+// Original license: SPDX_License_Identifier: MIT
+
+// Original pragma directive: pragma abicoder v2
+pragma solidity ^0.8.19;
+
+contract A {
+    uint256 private storedData;
+
+    function set(uint256 value) public {
+        storedData = value;
+    }
+
+    function get() public view returns (uint256) {
+        return storedData;
+    }
+}
+
+
+// File contracts/Lock.sol
+
+// Original license: SPDX_License_Identifier: UNLICENSED
+pragma solidity ^0.8.19;
+
+// Uncomment this line to use console.log
+// import "hardhat/console.sol";
+
+contract Lock {
+    uint public unlockTime;
+    address payable public owner;
+
+    event Withdrawal(uint amount, uint when);
+
+    constructor(uint _unlockTime) payable {
+        require(
+            block.timestamp < _unlockTime,
+            "Unlock time should be in the future"
+        );
+
+        unlockTime = _unlockTime;
+        owner = payable(msg.sender);
+    }
+
+    function withdraw() public {
+        // Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
+        // console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);
+
+        require(block.timestamp >= unlockTime, "You can't withdraw yet");
+        require(msg.sender == owner, "You aren't the owner");
+
+        emit Withdrawal(address(this).balance, block.timestamp);
+
+        owner.transfer(address(this).balance);
+    }
+}

e2e/fixture-projects/flatten/flatten_lock_file.txt

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+// Sources flattened with hardhat v2.19.2 https://hardhat.org
+
+// SPDX-License-Identifier: UNLICENSED
+
+// File contracts/Lock.sol
+
+// Original license: SPDX_License_Identifier: UNLICENSED
+pragma solidity ^0.8.19;
+
+// Uncomment this line to use console.log
+// import "hardhat/console.sol";
+
+contract Lock {
+    uint public unlockTime;
+    address payable public owner;
+
+    event Withdrawal(uint amount, uint when);
+
+    constructor(uint _unlockTime) payable {
+        require(
+            block.timestamp < _unlockTime,
+            "Unlock time should be in the future"
+        );
+
+        unlockTime = _unlockTime;
+        owner = payable(msg.sender);
+    }
+
+    function withdraw() public {
+        // Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
+        // console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);
+
+        require(block.timestamp >= unlockTime, "You can't withdraw yet");
+        require(msg.sender == owner, "You aren't the owner");
+
+        emit Withdrawal(address(this).balance, block.timestamp);
+
+        owner.transfer(address(this).balance);
+    }
+}

e2e/fixture-projects/flatten/hardhat.config.js

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+module.exports = {
+  solidity: "0.8.19",
+};

e2e/fixture-projects/flatten/package.json

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+{
+  "name": "minimal",
+  "dependencies": {
+    "hardhat": "file:../../../packages/hardhat-core/hardhat-2.19.1.tgz"
+  }
+}

e2e/fixture-projects/flatten/test.sh

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+#! /usr/bin/env sh
+
+# it should flatten all the files in the folder because no file names are passed
+if ! npx hardhat flatten | diff - flatten_all_files.txt; then
+    echo "The flatten file is different from the flatten_all_files.txt"
+    exit 1
+fi
+
+# it should flatten only the 'Lock.sol' file because it is passed as an argument
+if ! npx hardhat flatten contracts/Lock.sol | diff - flatten_lock_file.txt; then
+    echo "The flatten file is different from the flatten_lock_file.txt"
+    exit 1
+fi
+
+
+
+
+
+