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Agent skill

Test Guided Migration Assistant

by ArabelaTso in ArabelaTso/Skills-4-SE

Automatically updates a codebase to a new language version, framework version, or library update while ensuring all tests still pass.

Apache-2.0Auto-check passedBackend & APIs

Install Test Guided Migration Assistant

skills CLI
$ npx skills add ArabelaTso/Skills-4-SE --skill test-guided-migration-assistant -a claude-code

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

GitHub CLI
$ gh skill install ArabelaTso/Skills-4-SE test-guided-migration-assistant --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/ArabelaTso/Skills-4-SE.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/test-guided-migration-assistant .claude/skills/test-guided-migration-assistant && 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
test-guided-migration-assistant
GitHub stars
253
Token cost
~1.8k tokens
SKILL.md length
425 words
Files
4 (incl. scripts, references)
Skills in repo
150
Repo updated
First seen
Licence
Apache-2.0

At a glance

Automatically updates a codebase to a new language version, framework version, or library update while ensuring all tests still pass.

  • Works in 7 steps: Establish Baseline → Understand Migration Context → Perform Migration → …
  • Migrating Python 2→3
  • SKILL.md covers Workflow, Key Principles, Common Migration Patterns and Helper Script, plus 1 more section
  • Runs Python scripts from its folder; calls python, npm and git

What it does

Test Guided Migration Assistant is an agent skill from ArabelaTso/Skills-4-SE. Automatically updates a codebase to a new language version, framework version, or library update while ensuring all tests still pass. Use this skill when migrating Python 2→3, upgrading framework versions (React, Django, Angular), updating dependencies, or performing any version migration where tests define correct behavior. The skill analyzes failing tests caused by migration, categorizes errors (import errors, API changes, type errors, behavior changes), proposes systematic fixes, and verifies that…

Its SKILL.md is about 1.8k tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files, including scripts and reference files (for example `references/migration_scenarios.md`, `references/migration_strategy.md` and `scripts/analyze_test_failures.py`).

It sits in Backend & APIs, covering Backend development and Failing and flaky tests. It works with Django, React, Python and Angular. The repository describes itself as: A curated list of 180+ useful Claude Skills for Software Engineering and resources for customizing AI for SE workflows. The licence is Apache-2.0.

When your agent uses it

  • Migrating Python 2→3
  • Upgrading framework versions (React
  • Updating dependencies
  • Performing any version migration where tests define correct behavior

Example prompts

  • “/test-guided-migration-assistant”

Requirements

  • Python 3
  • Node.js
  • Docker

Workflow steps

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

  1. Establish Baseline
  2. Understand Migration Context
  3. Perform Migration
  4. Analyze Test Failures
  5. Fix Issues Systematically
  6. Verify Behavior Preservation
  7. Document Migration

What it can do on your machine

Read from SKILL.md and the folder at commit 4f38503. 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/ (Python), which the agent can run.

    Shell commands in SKILL.md call:

    • python
    • npm
    • git
    • pip
    • pytest
    • node

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use npm, git and pip, which can reach the network depending on how they are called.

    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 Guided Migration Assistant loads about 1.8k tokens when it runs, and up to ~5.3k if it reads all its reference files. Until then it costs about 188 tokens; SKILL.md has 425 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~188
When it runs · the whole SKILL.md, loaded when a task matches
~1.8k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~5.3k

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 ArabelaTso/Skills-4-SE at commit 4f38503, republished under its Apache-2.0 licence (© ArabelaTso). 425 words, ~1,820 tokens.

Download SKILL.mdSave it as .claude/skills/test-guided-migration-assistant/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.
name
test-guided-migration-assistant
description
Automatically updates a codebase to a new language version, framework version, or library update while ensuring all tests still pass. Use this skill when migrating Python 2→3, upgrading framework versions (React, Django, Angular), updating dependencies, or performing any version migration where tests define correct behavior. The skill analyzes failing tests caused by migration, categorizes errors (import errors, API changes, type errors, behavior changes), proposes systematic fixes, and verifies that test-observable behavior remains unchanged. Triggers when users ask to migrate code versions, upgrade dependencies while keeping tests passing, update framework versions, or perform test-guided version migrations.

Test-Guided Migration Assistant

Automatically update a codebase to a new language version, framework version, or library update while ensuring all tests continue to pass.

Workflow

1. Establish Baseline

Before starting migration, establish the current state:

bash
# Run full test suite
<test_command>

# Record baseline
# - Total tests: X
# - Passing: Y
# - Failing: Z (should be 0 or known failures)
# - Coverage: N%

Document current state:

  • Current versions (language, framework, dependencies)
  • Test results
  • Any known issues
2. Understand Migration Context

Gather information:

  • Target version (e.g., Python 3.12, React 18, Django 4.2)
  • Migration scope (single library vs. full stack)
  • Breaking changes expected

Consult migration guides:

  • Official migration documentation
  • Changelog/release notes
  • Community migration guides
  • See migration_scenarios.md for common patterns

Identify risks:

  • Deprecated API usage
  • Known breaking changes
  • Custom integrations affected
  • Performance implications
3. Perform Migration

Update dependencies:

Incremental approach (recommended):

bash
# Update one dependency at a time
npm install package@new-version
# or
pip install package==new-version

# Run tests immediately
<test_command>

Batch approach (for experienced migrations):

bash
# Update all dependencies
npm update
# or
pip install -U -r requirements.txt

# Run tests
<test_command>

Update configuration:

  • Update build configuration
  • Update CI/CD configuration
  • Update environment files
  • Update Docker images
4. Analyze Test Failures

Run tests and capture output:

bash
# Pytest
pytest -v > test_output.txt 2>&1

# Jest
npm test > test_output.txt 2>&1

# Other frameworks
<test_command> > test_output.txt 2>&1

Use analysis script:

bash
python scripts/analyze_test_failures.py test_output.txt

The script categorizes failures into:

  • 🔴 Import/Module Errors (CRITICAL - fix first)
  • 🟠 API Signature Errors (HIGH priority)
  • 🟡 Type Errors (MEDIUM priority)
  • 🟡 Configuration Errors (MEDIUM priority)
  • 🟢 Behavior Changes (review carefully)
  • 🔵 Deprecation Warnings (fix when possible)
5. Fix Issues Systematically

Follow priority order from analysis. See migration_strategy.md for detailed strategies.

Fix import errors first:

python
# Example: Module moved
# Old
from collections import Mapping

# New
from collections.abc import Mapping

Fix API signature errors:

python
# Example: Parameter renamed
# Old
result = function(arg1, old_param=value)

# New
result = function(arg1, new_param=value)

Fix type errors:

typescript
// Example: Stricter types
// Old
function process(value: string) { }

// New (handle undefined)
function process(value: string | undefined) {
  if (value === undefined) return;
  // ...
}

Handle behavior changes:

python
# Example: Changed defaults
# Old behavior: returns None on error
# New behavior: raises exception

# Add error handling
try:
    result = function()
except NewException:
    result = None  # Preserve old behavior

After each fix category:

bash
# Run tests
<test_command>

# Commit if tests pass
git add .
git commit -m "Fix: migration import errors"
6. Verify Behavior Preservation

Run full test suite multiple times:

bash
# Catch flaky tests
for i in {1..3}; do
  echo "Run $i"
  <test_command>
done

Verify coverage unchanged:

bash
# Generate coverage report
<coverage_command>

# Compare to baseline
# Should be same or better

Check for warnings:

bash
# Python
python -W all -m pytest

# Node.js
node --trace-warnings test

# Look for deprecation warnings

Success criteria:

  • All tests pass
  • Same number of passing tests as baseline
  • No new test failures
  • Coverage maintained or improved
  • Build succeeds
  • No critical warnings
7. Document Migration

Create migration summary:

MIGRATION SUMMARY
=================

Migration: Python 3.8 → Python 3.12

Changes Made:
- Updated collections imports (Mapping → collections.abc.Mapping)
- Fixed asyncio.coroutine → async def
- Updated type hints for stricter checking
- Removed distutils usage

Test Results:
- Before: 156/156 passing
- After: 156/156 passing
- Coverage: 87% (unchanged)

Breaking Changes Addressed:
1. Collections ABC moved
2. asyncio.coroutine removed
3. Type checking stricter

Deprecation Warnings:
- None remaining
Show full SKILL.md (173 more words)Show less

Key Principles

Tests Define Correctness: If tests pass, behavior is preserved.

Fix by Priority: Import errors block everything - fix first. Then API errors, then types, then behavior.

Incremental Changes: Fix one category, test, commit. Don't accumulate many changes.

Never Modify Tests: Fix the code to make tests pass. Don't change tests to match new behavior (unless behavior change is intentional and documented).

Fail Fast: Run tests immediately after migration attempt. Don't wait.

Common Migration Patterns

Python 2 → 3
  • print statement → print() function
  • xrange() → range()
  • .iteritems() → .items()
  • except Exception, e: → except Exception as e:
React 16 → 18
  • ReactDOM.render() → ReactDOM.createRoot().render()
  • Update for concurrent rendering
  • Fix useEffect timing issues
Django 2.2 → 4.2
  • django.conf.urls.url() → django.urls.re_path()
  • Update ugettext → gettext
  • Remove USE_L10N setting
Node.js 14 → 20
  • Update deprecated APIs
  • Fix OpenSSL changes
  • Update crypto usage

Helper Script

The analyze_test_failures.py script automates failure categorization:

bash
# Analyze pytest output
python scripts/analyze_test_failures.py test_output.txt

# Analyze Jest output
python scripts/analyze_test_failures.py test_output.txt --format jest

# Auto-detect format
python scripts/analyze_test_failures.py test_output.txt --format auto

Output provides:

  • Categorized failure list
  • Priority order for fixes
  • Example errors from each category
  • Recommended fix strategies

Rollback Strategy

If migration has too many failures (>20% of tests):

bash
# Revert dependency changes
git checkout HEAD -- package.json package-lock.json
npm install

# Or revert commits
git revert <commit-hash>

# Verify tests pass
<test_command>

Then plan incremental migration or allocate more time.

© ArabelaTso, Apache-2.0. 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 3 other files (scripts, references) in skills/test-guided-migration-assistant of ArabelaTso/Skills-4-SE.

  • SKILL.md
  • references/migration_scenarios.md
  • references/migration_strategy.md
  • scripts/analyze_test_failures.py

Open the folder on GitHubat commit 4f38503

Compare with similar skills

Test Guided Migration Assistant 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.

Test Guided Migration Assistant compared with similar skills
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Fullstack Devinfometa/workbuddyskills344—~1kAutomated safety check: PassMIT
Code Review Skillawesome-skills/code-review-skill2.1k—~2.8kAutomated safety check: NotesMIT
Maintaining Python TestsPostHog/posthog40k—~2.5kAutomated safety check: PassCustom licence
Design Patternswaybarrios/opencode-power-pack533—~2.2kAutomated safety check: PassMIT

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Works with

Categories

Questions about Test Guided Migration Assistant

What does Test Guided Migration Assistant do?

Automatically updates a codebase to a new language version, framework version, or library update while ensuring all tests still pass. Test Guided Migration Assistant is an agent skill from ArabelaTso/Skills-4-SE. Automatically updates a codebase to a new language version, framework version, or library update while ensuring all tests still pass.

When should I use Test Guided Migration Assistant?

Test Guided Migration Assistant fits situations like: migrating Python 2→3; upgrading framework versions (React; updating dependencies; performing any version migration where tests define correct behavior.

How do I install Test Guided Migration Assistant in Claude Code?

Run `npx skills add ArabelaTso/Skills-4-SE --skill test-guided-migration-assistant -a claude-code`. Or copy the skill folder (skills/test-guided-migration-assistant in ArabelaTso/Skills-4-SE) into .claude/skills/test-guided-migration-assistant in your project. Claude Code loads it when a task matches its description.

How do I install Test Guided Migration Assistant in Codex?

Run `npx skills add ArabelaTso/Skills-4-SE --skill test-guided-migration-assistant -a codex`. Or copy the skill folder (skills/test-guided-migration-assistant in ArabelaTso/Skills-4-SE) into .agents/skills/test-guided-migration-assistant in your project. Codex loads it when a task matches its description.

Can I use Test Guided Migration Assistant 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 ArabelaTso/Skills-4-SE --skill test-guided-migration-assistant -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-guided-migration-assistant, .gemini/skills/test-guided-migration-assistant, .github/skills/test-guided-migration-assistant and .opencode/skills/test-guided-migration-assistant in your project.

What does Test Guided Migration Assistant need to run?

Going by SKILL.md and its folder, Test Guided Migration Assistant needs Python for the scripts in its folder and the command-line tools its instructions call (python, npm, git, pip, pytest and node). Our summary lists: Python 3; Node.js; Docker.

Does Test Guided Migration Assistant access the network?

SKILL.md contains no URLs. Its commands use npm, git and pip, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Test Guided Migration Assistant 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 Test Guided Migration Assistant use?

Test Guided Migration Assistant is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Test Guided Migration Assistant use?

About 1.8k tokens (SKILL.md is roughly 7.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 3.5k tokens, read only when the agent opens those files.

What are the alternatives to Test Guided Migration Assistant?

Skills that share tags, products or a category with Test Guided Migration Assistant: Code Review Skill (Rain-kl/OpenFlare, 288 stars), Fullstack Dev (infometa/workbuddyskills, 344 stars), Code Review Skill (awesome-skills/code-review-skill, 2.1k stars) and Maintaining Python Tests (PostHog/posthog, 40k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Test Guided Migration Assistant?

ArabelaTso (a GitHub user) maintains it in ArabelaTso/Skills-4-SE, which has 253 GitHub stars. The repository holds 150 skills in this directory. The repository was last updated on August 21, 2026.

Source: ArabelaTso/Skills-4-SE on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.