foundry: vm.dumpState skips empty accounts (foundry-rs#6986)

* foundry: `vm.dumpState` skips empty accounts

Update `vm.dumpState` to also skip empty accounts.
Empty accounts are not particularly useful and would
otherwise require a postprocessing step after the state dump
to remove.

Adds a unit test showing that it works and updates an old unit
test as an empty account is defined by a nonce of 0, no balance
and no code. If there is storage, it still counts as an empty
account.

cargo fmt

* testdata: cleanup

crates/cheatcodes/src/evm.rs

@@ -97,22 +97,23 @@ impl Cheatcode for dumpStateCall {
         let Self { pathToStateJson } = self;
         let path = Path::new(pathToStateJson);
 
-        // Do not include system accounts in the dump.
-        let skip = |key: &Address| {
+        // Do not include system account or empty accounts in the dump.
+        let skip = |key: &Address, val: &Account| {
             key == &CHEATCODE_ADDRESS ||
                 key == &CALLER ||
                 key == &HARDHAT_CONSOLE_ADDRESS ||
                 key == &TEST_CONTRACT_ADDRESS ||
                 key == &ccx.caller ||
-                key == &ccx.state.config.evm_opts.sender
+                key == &ccx.state.config.evm_opts.sender ||
+                val.is_empty()
         };
 
         let alloc = ccx
             .data
             .journaled_state
             .state()
             .into_iter()
-            .filter(|(key, _)| !skip(key))
+            .filter(|(key, val)| !skip(key, val))
             .map(|(key, val)| {
                 (
                     key,

testdata/cheats/dumpState.t.sol

@@ -63,6 +63,7 @@ contract DumpStateTest is DSTest {
 
         vm.setNonce(address(0x100), 1);
         vm.deal(address(0x200), 1 ether);
+        vm.setNonce(address(0x300), 1);
         vm.store(address(0x300), bytes32(uint256(1)), bytes32(uint256(2)));
         vm.etch(address(0x400), hex"af");
 
@@ -85,7 +86,7 @@ contract DumpStateTest is DSTest {
         assertEq(0, vm.parseJsonKeys(json, string.concat(".", vm.toString(address(0x200)), ".storage")).length);
 
         assertEq(4, vm.parseJsonKeys(json, string.concat(".", vm.toString(address(0x300)))).length);
-        assertEq(0, vm.parseJsonUint(json, string.concat(".", vm.toString(address(0x300)), ".nonce")));
+        assertEq(1, vm.parseJsonUint(json, string.concat(".", vm.toString(address(0x300)), ".nonce")));
         assertEq(0, vm.parseJsonUint(json, string.concat(".", vm.toString(address(0x300)), ".balance")));
         assertEq(hex"", vm.parseJsonBytes(json, string.concat(".", vm.toString(address(0x300)), ".code")));
         assertEq(1, vm.parseJsonKeys(json, string.concat(".", vm.toString(address(0x300)), ".storage")).length);
@@ -120,4 +121,19 @@ contract DumpStateTest is DSTest {
 
         vm.removeFile(path);
     }
+
+    function testDumpStateEmptyAccount() public {
+        string memory path = string.concat(vm.projectRoot(), "/fixtures/Json/test_dump_state_empty_account.json");
+
+        SimpleContract s = new SimpleContract();
+        vm.etch(address(s), hex"");
+        vm.resetNonce(address(s));
+
+        vm.dumpState(path);
+        string memory json = vm.readFile(path);
+        string[] memory keys = vm.parseJsonKeys(json, "");
+        assertEq(keys.length, 0);
+
+        vm.removeFile(path);
+    }
 }