Neo DevPack for Solidity v0.26.0 — neo-test Dev Environment & Deep Correctness

neo-devpack-solidity v0.26.0 — neo-test Dev Environment & Deep Correctness

Release date: 2026-07-01
Compiler / CLI / workspace: v0.26.0
devpack (@neo-devpack-solidity/contracts): v0.26.0
Target Neo N3 node: v3.10.0 (Gorgon-prep; no hardfork activation)

Canonical change list: CHANGELOG.md [v0.26.0].
Previous releases: see the
GitHub releases page
and CHANGELOG.md history (previous: v0.25.0).

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TL;DR

• neo-test — a native, Foundry-style Solidity test runner that
  executes test* / testFail* / setUp() directly on the in-tree
  NeoVM, with per-test state isolation, cross-contract new, decoded
  revert / Panic reasons, console.log and gas reporting. Bundles
  neo-std/{Test,console,Vm}.sol, wired into neo-forge test. See
  docs/TESTING.md.
• Foundry cheatcodes — vm.prank / startPrank / stopPrank /
  warp / roll / deal / label / assume and vm.expectRevert()
  (via the HEVM address; no compiler change).
• A large correctness wave, dogfooded through neo-test and
  cargo-fuzz/proptest: arithmetic wrap/overflow, bytesN byte-order at
  every binding site, storage aliasing & deep-copy, low-level .call
  returndata, ABI encode/decode fidelity, event/inheritance merge, and
  try/catch semantics — 1952 tests across 54 targets, 0 failures.

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🧪 The headline: neo-test

Neo now has a first-class, Foundry-shaped testing story that runs on the
same NeoVM the compiler targets — no external node required for the inner
loop:

• Write tests in Solidity: function testTransfer() public { ... },
  testFail* for expected-revert, setUp() for per-test fixtures.
• Per-test state isolation and cross-contract new so multi-
  contract flows (Vault/deposit, factory patterns) work out of the box.
• Decoded failures — revert("msg"), require, custom errors and
  Panic(0xNN) come back as human-readable reasons, not raw bytes.
• console.log / console.logBytes, gas accounting, and
  value-rich assertions (assertEq failed: 3 != 5).
• Cheatcodes through the standard HEVM address: vm.prank,
  startPrank/stopPrank, warp, roll, deal, label, assume,
  and vm.expectRevert().

neo-forge test now delegates to neo-test. The bundled neo-std
(Test.sol, console.sol, Vm.sol) ships in-tree via include_str!.

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🔧 Correctness fixes (highlights)

Grouped; full list in CHANGELOG.md [v0.26.0]. Many
were found by dogfooding neo-test and by the fuzz harness, then
verified against a real neoxp node.

• Arithmetic — unchecked -type(intN).min / 0 - min now WRAP
  two's-complement (previously produced the out-of-range +2^(N-1),
  which also faulted NeoVM's 256-bit integer); addmod(a,b,0) /
  mulmod(a,b,0) Panic(0x12); addmod full-width carry; int256/
  uint256 ** via soft-arith magnitude (catchable Panic / wrap, no
  33-byte fault); mapping(K => uintN) value width.
• bytesN / byte semantics — integer-backed bytesN literals are
  big-endian at every binding site (scalar, struct field, array push,
  mapping key, call arg, return, constant, multi-return tuple, indexed
  event topic); bytesN bitwise read-back via uint256(...); b[i] is
  a bytes1; intN(bytesN) endianness; bytesN constant comparison
  (fixed a byte-reversed access-control check).
• Storage — storage struct passed by reference to an internal
  function aliases the slot; T[] memory m = storageArr deep-copies;
  storage bytes element write data[i] = v persists; bytes
  push/pop.
• ABI & low-level calls — internal call to a public array/bytes/
  string returner decodes the ABI blob; low-level .call returndata
  is the raw EVM ABI envelope (no Neo serialize framing), a no-reason
  revert is empty, and (bool ok, ) reports false on revert; strict
  abi.decode type fidelity; abi.encode/encodePacked ByteString;
  partial tuple destructure from a cross-contract call.
• Events / inheritance / merge — a contract keeps its own event
  declarations when another references it by type; a new-deployed
  contract's public method reaches its own concrete internal helper
  (was dropped → PUSH0 → write lost); cross-contract msg.sender for
  new-deployed callees.
• try/catch & control flow — bounded TRY nesting (VM-DoS fix) +
  uncatchable ExecutionEngineLimits; catch Panic/catch Error
  matching against real-node faults; balanced TRY frame on every catch
  exit; modifier/base-constructor args evaluated exactly once.
• Type resolution & devpack — integer-literal overload resolution;
  address.balance/.code/.codehash inference; NeoVM EQUAL
  type-strictness; devpack multiSigMint authorization, stake-reward
  settlement, NEP-11 oracle/curation/minter-royalty paths.

Known limitations (tracked for a follow-up)

A handful of deep sim-fidelity / model-level items are documented but not
yet fixed: abi.encodeWithSignature used as raw bytes vs. the Neo
method-name .call optimization; abi.encode of fixed-size arrays
(uintN[K]) using dynamic layout; nested struct-array-member storage
keys; inherited-getter dispatch and inherited base-constructor state when
a contract is instantiated via new in the in-tree simulator.

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📊 Headline numbers

Metric	v0.25.0	v0.26.0
Native Solidity test runner	—	neo-test
Foundry cheatcodes	—	9 (prank/warp/roll/deal/label/assume/expectRevert/…)
Test suites green	47	54
Total tests	1,488	1,952
Test failures	0	0
Backlog compiler bugs fixed this cycle	—	30+

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🚀 How to upgrade

Backwards-compatible release — no public-API breaks or renames. Cargo and
npm users pick up v0.26.0 on their next dependency resolution.

CLI users: rebuild with cargo install --path . --version 0.26.0
or download the prebuilt binary from the
release page.

Library users consuming neo_devpack_solidity from another crate:
pick up 0.26.0 via cargo update.

devpack users: npm install @neo-devpack-solidity/contracts@0.26.0.

Test authors: write Solidity tests and run neo-test <file>.sol
(or neo-forge test). See docs/TESTING.md.

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🧪 Verification

• cargo test --release ✅ 1,952 passed / 54 targets / 0 failed
  (integration + lib unit + cargo-fuzz/proptest)
• cargo fmt --all -- --check ✅
• cargo clippy ✅