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Agent skill

Build Setup

by OpenHands in OpenHands/extensions

Set up build environment and test fixtures for COBOL-to-Java migrations.

MITAuto-check passedTesting & QA

Install Build Setup

skills CLI
$ npx skills add OpenHands/extensions --skill build-setup -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install OpenHands/extensions build-setup --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/cobol-modernization/skills/build-setup .claude/skills/build-setup && rm -rf skills-src

Use ~/.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/

Facts

Skill name
build-setup
GitHub stars
157
Token cost
~624 tokens
SKILL.md length
229 words
Files
2 (incl. scripts)
Skills in repo
78
Repo updated
First seen
Licence
MIT

At a glance

Set up build environment and test fixtures for COBOL-to-Java migrations.

  • Works in 2 steps: Build Setup → Test Fixture Generation
  • Tasks that involve Test data and fixtures
  • SKILL.md covers Phase 1: Build Setup, Phase 2: Test Fixture Generation, Deliverables and Priority
  • Runs Shell scripts from its folder; calls bash

What it does

Build Setup is an agent skill from OpenHands/extensions. Set up build environment and test fixtures for COBOL-to-Java migrations. Creates compilation infrastructure for both languages and generates golden test data.

Its SKILL.md is about 620 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including scripts (for example `scripts/install-gnucobol.sh`). Compatibility notes: Requires GnuCOBOL (cobc), Java 11+, Maven or Gradle

It sits in Testing & QA, covering Test data and fixtures. It works with Java. The repository describes itself as: Public registry for OpenHands extensions. The licence is MIT.

When your agent uses it

  • Tasks that involve Test data and fixtures

Example prompts

  • “/build-setup”

Requirements

  • A Bash shell
  • Compatibility (from SKILL.md): Requires GnuCOBOL (cobc), Java 11+, Maven or Gradle

Workflow steps

2 steps, taken from the step headings in SKILL.md.

  1. Build Setup
  2. Test Fixture Generation

What it can do on your machine

Read from SKILL.md and the folder at commit d008b81. 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

    Ships 1 file in scripts/ (Shell), which the agent can run.

    Shell commands in SKILL.md call:

    • bash

    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.

  • Compatibility

    Requires GnuCOBOL (cobc), Java 11+, Maven or Gradle

    From compatibility in the SKILL.md frontmatter.

Context cost

Build Setup loads about 624 tokens when it runs. Until then it costs about 43 tokens; SKILL.md has 229 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~43
When it runs · the whole SKILL.md, loaded when a task matches
~624

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); the scripts in this folder are not scanned.

SKILL.md

The full file from OpenHands/extensions at commit d008b81, republished under its MIT licence (© OpenHands). 229 words, ~624 tokens.

Download SKILL.mdSave it as .claude/skills/build-setup/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
build-setup
description
Set up build environment and test fixtures for COBOL-to-Java migrations. Creates compilation infrastructure for both languages and generates golden test data.
compatibility
Requires GnuCOBOL (cobc), Java 11+, Maven or Gradle
license
MIT
triggers
cobol build, cobol test fixtures, migration build setup, gnucobol

Set up a build environment and create test fixtures for validating COBOL-to-Java migrations.

To install GnuCOBOL, run: ./scripts/install-gnucobol.sh On Windows, run that shell script from Git Bash/WSL (bash scripts/install-gnucobol.sh) or install GnuCOBOL with a Windows package manager and document the chosen command in build_notes.md.

Phase 1: Build Setup

COBOL Build
  • Find a way to compile and run the COBOL code (e.g., GnuCOBOL)
  • Verify at least one program compiles and executes
  • Note any dependencies or setup required
Java Build
  • Initialize a Java project alongside the COBOL code (Maven or Gradle)
  • Set up standard directory structure: src/main/java, src/test/java
  • Include JUnit 5 as a test dependency
  • Verify the project builds (even if empty)

Phase 2: Test Fixture Generation

For each major COBOL program:

Create Synthetic Test Inputs
  • Save to: test-fixtures/inputs/{PROGRAM_NAME}/
  • Create 3-5 test cases per program covering:
    • Normal/happy path (valid, typical data)
    • Edge cases (empty input, maximum values, boundary conditions)
    • Error cases (invalid formats, missing required fields)
Generate Golden Outputs
  • Run each COBOL program with each test input
  • Save COBOL output to: test-fixtures/expected_outputs/{PROGRAM_NAME}/
  • These become the "golden" outputs that Java must match
Create Test Manifest

Save to test_manifest.json:

json
{
  "PROGRAM1": {
    "description": "Brief description of what this program does",
    "test_cases": [
      {
        "name": "normal_invoice",
        "input": "inputs/PROGRAM1/test_001.dat",
        "expected": "expected_outputs/PROGRAM1/test_001.out",
        "description": "Happy path"
      }
    ]
  }
}

Deliverables

  1. build_notes.md — Build instructions for COBOL and Java
  2. test-fixtures/ — Directory with inputs/ and expected_outputs/
  3. test_manifest.json — JSON manifest of all test cases

Priority

Focus on programs with core business logic (transactions, calculations, data processing). UI-heavy programs (menu screens, reports) are lower priority.

© OpenHands, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (scripts) in plugins/cobol-modernization/skills/build-setup of OpenHands/extensions.

  • SKILL.md
  • scripts/install-gnucobol.sh

Open the folder on GitHubat commit d008b81

Compare with similar skills

Build Setup 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.

Build Setup compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Build Setup this skillOpenHands/extensions157—~624Automated safety check: PassMIT
Java SDK E2E Test with Replay Snapshotgithub/copilot-sdk11k—~1.8kAutomated safety check: PassMIT
133 Java Testing Acceptance Testsjabrena/plinth445—~1.3kAutomated safety check: PassApache-2.0
Jest Testing PatternsChrisWiles/claude-code-showcase6.1k7 repos~1.5kAutomated safety check: PassNone
source-mssql E2E Test Harnessairbytehq/airbyte22k—~4.4kAutomated safety check: PassCustom licence
RTK Filter TDD in Rustrtk-ai/rtk83k—~1.9kAutomated safety check: NotesApache-2.0

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Works with

Categories

Questions about Build Setup

What does Build Setup do?

Set up build environment and test fixtures for COBOL-to-Java migrations. Build Setup is an agent skill from OpenHands/extensions. Set up build environment and test fixtures for COBOL-to-Java migrations.

When should I use Build Setup?

Build Setup fits situations like: tasks that involve Test data and fixtures.

How do I install Build Setup in Claude Code?

Run `npx skills add OpenHands/extensions --skill build-setup -a claude-code`. Or copy the skill folder (plugins/cobol-modernization/skills/build-setup in OpenHands/extensions) into .claude/skills/build-setup in your project. Claude Code loads it when a task matches its description.

How do I install Build Setup in Codex?

Run `npx skills add OpenHands/extensions --skill build-setup -a codex`. Or copy the skill folder (plugins/cobol-modernization/skills/build-setup in OpenHands/extensions) into .agents/skills/build-setup in your project. Codex loads it when a task matches its description.

Can I use Build Setup 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 OpenHands/extensions --skill build-setup -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/build-setup, .gemini/skills/build-setup, .github/skills/build-setup and .opencode/skills/build-setup in your project.

What does Build Setup need to run?

Going by SKILL.md and its folder, Build Setup needs a shell for the scripts in its folder and the command-line tools its instructions call (bash). Our summary lists: A Bash shell. Compatibility (from SKILL.md): Requires GnuCOBOL (cobc), Java 11+, Maven or Gradle.

Does Build Setup 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 Build Setup 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. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Build Setup use?

Build Setup is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Build Setup use?

About 624 tokens (SKILL.md is roughly 2.5k 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 Build Setup?

Skills that share tags, products or a category with Build Setup: Java SDK E2E Test with Replay Snapshot (github/copilot-sdk, 11k stars), 133 Java Testing Acceptance Tests (jabrena/plinth, 445 stars), Jest Testing Patterns (ChrisWiles/claude-code-showcase, 6.1k stars) and source-mssql E2E Test Harness (airbytehq/airbyte, 22k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Build Setup?

OpenHands (a GitHub organization) maintains it in OpenHands/extensions, which has 157 GitHub stars. The repository holds 78 skills in this directory. The repository was last updated on October 6, 2026.

Source: OpenHands/extensions on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.