feat(ctb): gov token interface tests

Adds basic tests to check for the ERC20 interface on the
GovernanceToken.

packages/contracts-bedrock/.gas-snapshot

@@ -28,6 +28,16 @@ GasPriceOracle_Test:test_overhead_succeeds() (gas: 10546)
 GasPriceOracle_Test:test_scalar_succeeds() (gas: 10611)
 GasPriceOracle_Test:test_setGasPrice_doesNotExist_reverts() (gas: 5910)
 GasPriceOracle_Test:test_setL1BaseFee_doesNotExist_reverts() (gas: 5910)
+GovernanceToken_Test:test_approve_succeeds() (gas: 133293)
+GovernanceToken_Test:test_burnFrom_succeeds() (gas: 122733)
+GovernanceToken_Test:test_burn_succeeds() (gas: 114610)
+GovernanceToken_Test:test_constructor_succeeds() (gas: 21275)
+GovernanceToken_Test:test_decreaseAllowance_succeeds() (gas: 136985)
+GovernanceToken_Test:test_increaseAllowance_succeeds() (gas: 137073)
+GovernanceToken_Test:test_mint_fromNotOwner_reverts() (gas: 17052)
+GovernanceToken_Test:test_mint_fromOwner_succeeds() (gas: 108547)
+GovernanceToken_Test:test_transferFrom_succeeds() (gas: 146295)
+GovernanceToken_Test:test_transfer_succeeds() (gas: 138085)
 Hashing_Test:test_hashDepositSource_succeeds() (gas: 650)
 L1BlockTest:test_basefee_succeeds() (gas: 7553)
 L1BlockTest:test_hash_succeeds() (gas: 7510)

packages/contracts-bedrock/contracts/test/GovernanceToken.t.sol

+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.15;
+
+import { CommonTest } from "./CommonTest.t.sol";
+import { GovernanceToken } from "../governance/GovernanceToken.sol";
+
+contract GovernanceToken_Test is CommonTest {
+    address constant owner = address(0x1234);
+    address constant rando = address(0x5678);
+    GovernanceToken internal gov;
+
+    function setUp() external {
+        vm.prank(owner);
+        gov = new GovernanceToken();
+    }
+
+    function test_constructor_succeeds() external {
+        assertEq(gov.owner(), owner);
+        assertEq(gov.name(), "Optimism");
+        assertEq(gov.symbol(), "OP");
+        assertEq(gov.decimals(), 18);
+        assertEq(gov.totalSupply(), 0);
+    }
+
+    function test_mint_fromOwner_succeeds() external {
+        // Mint 100 tokens.
+        vm.prank(owner);
+        gov.mint(owner, 100);
+
+        // Balances have updated correctly.
+        assertEq(gov.balanceOf(owner), 100);
+        assertEq(gov.totalSupply(), 100);
+    }
+
+    function test_mint_fromNotOwner_reverts() external {
+        // Mint 100 tokens as rando.
+        vm.prank(rando);
+        vm.expectRevert("Ownable: caller is not the owner");
+        gov.mint(owner, 100);
+
+        // Balance does not update.
+        assertEq(gov.balanceOf(owner), 0);
+        assertEq(gov.totalSupply(), 0);
+    }
+
+    function test_burn_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando burns their tokens.
+        vm.prank(rando);
+        gov.burn(50);
+
+        // Balances have updated correctly.
+        assertEq(gov.balanceOf(rando), 50);
+        assertEq(gov.totalSupply(), 50);
+    }
+
+    function test_burnFrom_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando approves owner to burn 50 tokens.
+        vm.prank(rando);
+        gov.approve(owner, 50);
+
+        // Owner burns 50 tokens from rando.
+        vm.prank(owner);
+        gov.burnFrom(rando, 50);
+
+        // Balances have updated correctly.
+        assertEq(gov.balanceOf(rando), 50);
+        assertEq(gov.totalSupply(), 50);
+    }
+
+    function test_transfer_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando transfers 50 tokens to owner.
+        vm.prank(rando);
+        gov.transfer(owner, 50);
+
+        // Balances have updated correctly.
+        assertEq(gov.balanceOf(owner), 50);
+        assertEq(gov.balanceOf(rando), 50);
+        assertEq(gov.totalSupply(), 100);
+    }
+
+    function test_approve_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando approves owner to spend 50 tokens.
+        vm.prank(rando);
+        gov.approve(owner, 50);
+
+        // Allowances have updated.
+        assertEq(gov.allowance(rando, owner), 50);
+    }
+
+    function test_transferFrom_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando approves owner to spend 50 tokens.
+        vm.prank(rando);
+        gov.approve(owner, 50);
+
+        // Owner transfers 50 tokens from rando to owner.
+        vm.prank(owner);
+        gov.transferFrom(rando, owner, 50);
+
+        // Balances have updated correctly.
+        assertEq(gov.balanceOf(owner), 50);
+        assertEq(gov.balanceOf(rando), 50);
+        assertEq(gov.totalSupply(), 100);
+    }
+
+    function test_increaseAllowance_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando approves owner to spend 50 tokens.
+        vm.prank(rando);
+        gov.approve(owner, 50);
+
+        // Rando increases allowance by 50 tokens.
+        vm.prank(rando);
+        gov.increaseAllowance(owner, 50);
+
+        // Allowances have updated.
+        assertEq(gov.allowance(rando, owner), 100);
+    }
+
+    function test_decreaseAllowance_succeeds() external {
+        // Mint 100 tokens to rando.
+        vm.prank(owner);
+        gov.mint(rando, 100);
+
+        // Rando approves owner to spend 100 tokens.
+        vm.prank(rando);
+        gov.approve(owner, 100);
+
+        // Rando decreases allowance by 50 tokens.
+        vm.prank(rando);
+        gov.decreaseAllowance(owner, 50);
+
+        // Allowances have updated.
+        assertEq(gov.allowance(rando, owner), 50);
+    }
+}