Code Splitting
thedaviddias/Front-End-Checklist
A skill your agent uses when reviewing large SPA bundles, new dependency additions, or routes that feel slow to hydrate.
Protocol for splitting test files that approach or exceed the FR-006 500-line limit (enforced in CI by scripts/check-test-file-cap.ts as a diff-scoped ratchet).
MITAuto-check passed
Install Test File Split
$ npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install ZaxbyHub/opencode-swarm test-file-split --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/ZaxbyHub/opencode-swarm.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/test-file-split .claude/skills/test-file-split && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "test-file-split" agent skill from https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-split into .claude/skills/test-file-split/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-file-split", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-splitType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install ZaxbyHub/opencode-swarm test-file-split --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ZaxbyHub/opencode-swarm.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/test-file-split .agents/skills/test-file-split && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "test-file-split" agent skill from https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-split into .agents/skills/test-file-split/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-file-split", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install ZaxbyHub/opencode-swarm test-file-split --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ZaxbyHub/opencode-swarm.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/test-file-split .cursor/skills/test-file-split && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "test-file-split" agent skill from https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-split into .cursor/skills/test-file-split/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-file-split", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/ZaxbyHub/opencode-swarm.git --path .agents/skills/test-file-split--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install ZaxbyHub/opencode-swarm test-file-split --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ZaxbyHub/opencode-swarm.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/test-file-split .gemini/skills/test-file-split && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "test-file-split" agent skill from https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-split into .gemini/skills/test-file-split/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-file-split", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install ZaxbyHub/opencode-swarm test-file-splitInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/ZaxbyHub/opencode-swarm.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/test-file-split .github/skills/test-file-split && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "test-file-split" agent skill from https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-split into .github/skills/test-file-split/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-file-split", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install ZaxbyHub/opencode-swarm test-file-split --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/ZaxbyHub/opencode-swarm.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/test-file-split .opencode/skills/test-file-split && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "test-file-split" agent skill from https://github.com/ZaxbyHub/opencode-swarm/tree/main/.agents/skills/test-file-split into .opencode/skills/test-file-split/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-file-split", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
test-file-split- GitHub stars
- 490
- Token cost
- ~1.3k tokens
- SKILL.md length
- 510 words
- Files
- 1
- Skills in repo
- 91
- Repo updated
- First seen
- Licence
- MIT
At a glance
Protocol for splitting test files that approach or exceed the FR-006 500-line limit (enforced in CI by scripts/check-test-file-cap.ts as a diff-scoped ratchet).
- Works in 6 steps: Measure and identify split boundaries → Choose a suffix for the new file → Manage shared imports and helpers → …
- SKILL.md covers When to use this skill, Step 1 — Measure and identify…, Step 2 — Choose a suffix for… and Step 3 — Manage shared imports…, plus 5 more sections
- Calls bun
What it does
Test File Split is an agent skill from ZaxbyHub/opencode-swarm. Protocol for splitting test files that approach or exceed the FR-006 500-line limit (enforced in CI by scripts/check-test-file-cap.ts as a diff-scoped ratchet). Covers describe-block extraction, shared helper management, pure-function extraction, mock isolation verification, and cascading-split detection. Load when a test file approaches or exceeds 500 lines.
Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
The repository describes itself as: Architect-centric agentic swarm plugin for OpenCode. Hub-and-spoke orchestration with SME consultation, code generation, and QA review. The licence is MIT.
Example prompts
- “/test-file-split”
Workflow steps
6 steps, taken from the step headings in SKILL.md.
What it can do on your machine
Read from SKILL.md and the folder at commit 624cb60. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
bun
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Test File Split loads about 1.3k tokens when it runs. Until then it costs about 94 tokens; SKILL.md has 510 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from ZaxbyHub/opencode-swarm at commit 624cb60, republished under its MIT licence (© ZaxbyHub). 510 words, ~1,318 tokens.
Download SKILL.mdSave it as
.claude/skills/test-file-split/SKILL.md (or your agent's skills folder).- name
- test-file-split
- description
- Protocol for splitting test files that approach or exceed the FR-006 500-line limit (enforced in CI by scripts/check-test-file-cap.ts as a diff-scoped ratchet). Covers describe-block extraction, shared helper management, pure-function extraction, mock isolation verification, and cascading-split detection. Load when a test file approaches or exceeds 500 lines.
- audience
- swarm-plugin
Test File Split Protocol (FR-006)
scripts/check-test-file-cap.ts enforces the 500-line cap per test file (FR-006 / SC-006.1) as a diff-scoped ratchet: new test files over 500 lines and existing over-cap files that grew fail the quality gate and block PR merge. Pre-existing over-cap files not touched by the PR are non-blocking. Escape hatch: TEST_CAP_ENFORCE=0 soft-warns. This skill covers the complete splitting protocol.
Read first: .opencode/skills/writing-tests/SKILL.md (or .claude/skills/writing-tests/SKILL.md) for bun:test framework rules, mock isolation patterns, and file placement conventions.
When to use this skill
- A test file exceeds or approaches 500 lines
- CI fails with an FR-006 file-size violation
- You are adding tests to a file that is already above 400 lines (proactive split)
Step 1 — Measure and identify split boundaries
# Check the file
wc -l tests/unit/scripts/my-module.test.ts
# Find all test files exceeding 400 lines (early warning)
find tests/ -name "*.test.ts" -exec wc -l {} \; | sort -rn | awk '$1 > 400'Identify natural describe() block boundaries. Group blocks by functional area:
- Each
describe()block should belong to exactly one split file - Shared
beforeEach/afterEachhooks determine which blocks must stay together
Step 2 — Choose a suffix for the new file
| Pattern | Example | When to use |
|---|---|---|
<module>-<area>.test.ts | release-notes-fragments-sha.test.ts | Split by functional area (SHA resolution, validation, merge logic) |
<module>-<area>.adversarial.test.ts | auth-login.adversarial.test.ts | Split adversarial tests into their own file |
Step 3 — Manage shared imports and helpers
Three options, in order of preference:
Extract to shared utility (preferred for complex shared setup): Create
tests/helpers/<module>-shared.tswith shared fixtures, mock factories, and setup functions. Import from both split files.Duplicate simple imports (for small overlap): If only
bun:testimports and 1-2 source imports are shared, duplicate them in both files. Simpler than a utility module for trivial cases.Extract pure functions from source (for testability): If the source module has inline validation logic, extract them as exported pure functions (e.g.,
isValidPrNumber,resolveAllCandidates) so both test files can target them independently. See the PR #1762 example below. See.opencode/skills/generated/safe-extraction/SKILL.mdfor the source extraction pattern.
Show full SKILL.md (215 more words)Show less
Step 4 — Extract and move describe blocks
- Cut the selected
describe()blocks from the original file. - Paste them into the new file.
- Add all necessary imports to the new file.
- Remove now-unused imports from the original file.
Step 5 — Verify both files
Line count check
wc -l tests/unit/scripts/my-module.test.ts tests/unit/scripts/my-module-sha.test.ts
# Both must be under 500 linesIsolated run
bun --smol test tests/unit/scripts/my-module.test.ts --timeout 60000
bun --smol test tests/unit/scripts/my-module-sha.test.ts --timeout 60000Co-run (mock isolation verification)
# Critical: Bun shares a single process across test files.
# mock.module leaks can cause co-run failures even when isolated runs pass.
bun --smol test tests/unit/scripts/my-module*.test.ts --timeout 60000If the co-run fails but isolated runs pass, check for mock.module() leakage. See .opencode/skills/writing-tests/SKILL.md → "Mock Isolation Rules" and the _internals DI seam pattern.
Step 6 — Evaluate _test_exports opportunity
After splitting, evaluate whether internal utility functions in the source module can be exported via _test_exports for zero-mock testing. This is a natural cleanup moment — the split already forces you to review test coverage boundaries.
Cascading split warning
If a previously split file exceeds 500 lines again, the test suite is structurally too large for a single module. Do not split a third time — reorganize the tests by source module boundaries instead. Repeated splitting produces fragmented test suites that are hard to navigate and maintain.
Real-world example (PR #1762)
tests/unit/scripts/release-notes-fragments.test.ts exceeded 500 lines. It was split into:
| File | Lines | Content |
|---|---|---|
release-notes-fragments.test.ts | 379 | Fragment collection, deduplication, output formatting |
release-notes-fragments-sha.test.ts | 261 | extractCommitShasFromBody, mergeCandidateLists, resolveAllCandidates, isValidPrNumber, stripCustomReleaseNotesBlock |
The split also extracted isValidPrNumber and resolveAllCandidates as pure exported functions from the source module, enabling independent testing.
© ZaxbyHub, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in .agents/skills/test-file-split of ZaxbyHub/opencode-swarm.
Open the folder on GitHubat commit 624cb60
Compare with similar skills
Test File Split next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Test File Split this skillZaxbyHub/opencode-swarm | 490 | — | ~1.3k | Automated safety check: Pass | MIT | |
| Code Splittingthedaviddias/Front-End-Checklist | 74k | — | ~492 | Automated safety check: Pass | MIT | |
| Splitting Oversized ModulesPostHog/posthog | 40k | — | ~2.2k | Automated safety check: Pass | Custom licence | |
| SplitsBankrBot/skills | 1.2k | — | ~3.9k | Automated safety check: Pass | None | |
| Mcore Split PRNVIDIA/Megatron-LM | 18k | — | ~1.4k | Automated safety check: Pass | Apache-2.0 | |
| Stack Split Commitmozilla-firefox/firefox | 13k | — | ~1.3k | Automated safety check: Pass | Custom licence |
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Questions about Test File Split
What does Test File Split do?
Protocol for splitting test files that approach or exceed the FR-006 500-line limit (enforced in CI by scripts/check-test-file-cap.ts as a diff-scoped ratchet). Test File Split is an agent skill from ZaxbyHub/opencode-swarm.ts as a diff-scoped ratchet).
How do I install Test File Split in Claude Code?
Run `npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a claude-code`. Or copy the skill folder (.agents/skills/test-file-split in ZaxbyHub/opencode-swarm) into .claude/skills/test-file-split in your project. Claude Code loads it when a task matches its description.
How do I install Test File Split in Codex?
Run `npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a codex`. Or copy the skill folder (.agents/skills/test-file-split in ZaxbyHub/opencode-swarm) into .agents/skills/test-file-split in your project. Codex loads it when a task matches its description.
Can I use Test File Split in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ZaxbyHub/opencode-swarm --skill test-file-split -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/test-file-split, .gemini/skills/test-file-split, .github/skills/test-file-split and .opencode/skills/test-file-split in your project.
What does Test File Split need to run?
Going by SKILL.md and its folder, Test File Split needs the command-line tools its instructions call (bun).
Does Test File Split access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Test File Split safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Test File Split use?
Test File Split is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Test File Split use?
About 1.3k tokens (SKILL.md is roughly 5.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Test File Split?
Skills that share tags, products or a category with Test File Split: Code Splitting (thedaviddias/Front-End-Checklist, 74k stars), Splitting Oversized Modules (PostHog/posthog, 40k stars), Splits (BankrBot/skills, 1.2k stars) and Mcore Split PR (NVIDIA/Megatron-LM, 18k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Test File Split?
ZaxbyHub (a GitHub organization) maintains it in ZaxbyHub/opencode-swarm, which has 490 GitHub stars. The repository holds 91 skills in this directory. The repository was last updated on October 7, 2026.
Source: ZaxbyHub/opencode-swarm on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.