Create PendingBlkTimeAndNrAdvanceCheck.sol

src/mocks/PendingBlkTimeAndNrAdvanceCheck.sol

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+// Copyright 2021-2022, Offchain Labs, Inc.
+// For license information, see https://github.com/OffchainLabs/nitro-contracts/blob/main/LICENSE
+// SPDX-License-Identifier: BUSL-1.1
+
+pragma solidity ^0.8.0;
+
+import "../precompiles/ArbSys.sol";
+
+contract PendingBlkTimeAndNrAdvanceCheck {
+    uint256 immutable deployedAt;
+    uint256 immutable deployedAtBlock;
+    ArbSys constant ARB_SYS = ArbSys(address(100));
+
+    constructor() {
+        deployedAt = block.timestamp;
+        deployedAtBlock = ARB_SYS.arbBlockNumber();
+    }
+
+    function isAdvancing() external {
+        require(block.timestamp > deployedAt, "Time didn't advance");
+        require(ARB_SYS.arbBlockNumber() > deployedAtBlock, "Block didn't advance");
+    }
+
+    function checkArbBlockHashReturnsLatest(bytes32 expected) external {
+        bytes32 gotBlockHash = ARB_SYS.arbBlockHash(ARB_SYS.arbBlockNumber() - 1);
+        require(gotBlockHash != bytes32(0), "ZERO_BLOCK_HASH");
+        require(gotBlockHash == expected, "WRONG_BLOCK_HASH");
+    }
+}