Initial fixed array size implementation

[aaroncox]

Resolves #118

[Copilot]

Pull Request Overview

This PR adds support for fixed-size arrays in the ABI definitions, serialization logic, and encoding routines, and includes tests validating the new behavior.

• Introduces a size modifier for fixed-length arrays and updates ABI synthesis and type formatting to emit [N] syntax.
• Adjusts the encoder to omit the length prefix for fixed-size arrays.
• Updates chain ABI parsing to recognize and preserve [N] in type names, plus tests for encoding/decoding fixed-size arrays.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/chain.ts	Added tests for fixed-size array handling in ABI and encoding
src/serializer/serializable.ts	Added size modifier and updated synthesizeABI/abiTypeString
src/serializer/encoder.ts	Modified encodeAny to skip length prefix for fixed-size arrays
src/chain/abi.ts	Extended ABI parser to detect and represent fixed-size arrays
Makefile	Updated Mocha options with --no-experimental-strip-types
.github/workflows/test.yml	Expanded CI matrix to include Node.js 20, 22, and 24 versions

Comments suppressed due to low confidence (1)

test/chain.ts:867

• Add a test case to verify that providing an array with incorrect length for a fixed-size field throws a clear error, ensuring the validation path is covered.

    })

[Copilot]

Replace if (!type.size) with if (type.size === undefined) so that a fixed-size array of length 0 is not treated as a dynamic array and does not get a length prefix.

Suggested change

	if (!type.size) {
	if (type.size === undefined) {

[dafuga]

I guess we could make this change, but it's probably fine to leave it as is cause I don't think that many devs are going to use an array of length 0 😅

[greg7mdp]

for what it's worth, arrays of size 0 are explicitely not supported in the abi, so this could be treated as an error: https://github.com/AntelopeIO/spring/wiki/ABI-1.3:-Fixed-sized-arrays

[Copilot]

Add a validation after computing len to ensure that when type.size is defined, len matches type.size, e.g., if (type.size !== undefined && len !== type.size) throw new Error(Expected fixed-size array of length ${type.size} for: ${type.typeName});.

Suggested change

	const len = value.length
	const len = value.length
	if (type.size !== undefined && len !== type.size) {
	throw new Error(`Expected fixed-size array of length ${type.size} for: ${type.typeName}`)
	}

[dafuga]

I don't know if we want to throw an error in this situation..

[dafuga]

LGTM 👍