# Elixir Quality Gate

> Run comprehensive Elixir quality checks (format, credo, dialyzer, tests) with proper error handling and reporting. Use when validating code quality, before commits, or preparing for deployment. Use when this capability is needed.

- Skill: `tomevault-io/elixir-quality-gate` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/elixir-quality-gate`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/elixir-quality-gate/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/elixir-quality-gate

---


# Elixir Quality Gate

This skill runs comprehensive quality checks on Elixir/Phoenix projects following best practices.

## When to Use

- Before creating commits
- After implementing new features
- Before merging pull requests
- When preparing for deployment
- During code reviews

## Quality Checks Performed

### 1. Code Formatting
```bash
mix format --check-formatted
```
- Validates all files are properly formatted
- Fails fast if formatting issues found
- Shows which files need formatting

### 2. Compilation
```bash
mix compile --warnings-as-errors
```
- Ensures clean compilation
- Treats warnings as errors
- Catches unused variables, deprecated functions

### 3. Static Analysis (Credo)
```bash
mix credo --strict
```
- Runs strict code quality checks
- Checks for consistency, design issues, readability
- Reports refactoring opportunities

### 4. Type Checking (Dialyzer)
```bash
mix dialyzer
```
- Performs static type analysis
- Builds PLT (Persistent Lookup Table) if needed
- First run takes 1-2 minutes, subsequent runs are fast
- Catches type errors and inconsistencies

### 5. Test Suite
```bash
mix test
```
- Runs full test suite
- Reports coverage if configured
- Shows failures and pending tests

## Usage Pattern

### Full Quality Gate (Recommended)
Run all checks in sequence:
```bash
mix format --check-formatted && \
mix compile --warnings-as-errors && \
mix credo --strict && \
mix dialyzer && \
mix test
```

### Quick Check (Pre-commit)
If project has a precommit alias:
```bash
mix precommit
```

### Individual Checks
Run specific checks when iterating:
```bash
# Just format
mix format

# Just tests
mix test

# Specific test file
mix test test/my_app/accounts_test.exs

# Just credo
mix credo --strict
```

## Error Handling

**Format Failures:**
- Read the output to see which files need formatting
- Run `mix format` to fix automatically
- Re-run checks

**Compilation Warnings:**
- Read warnings carefully
- Common issues: unused variables (prefix with _), deprecated functions
- Fix warnings before proceeding

**Credo Issues:**
- Review suggested improvements
- Refactoring opportunities are optional but recommended
- Design and consistency issues should be addressed

**Dialyzer Errors:**
- First run builds PLT (takes time, this is normal)
- Type errors indicate potential runtime bugs
- Use @spec annotations to guide Dialyzer

**Test Failures:**
- Read failure messages carefully
- Run failing test in isolation: `mix test test/path/to/test.exs:LINE`
- Fix failures before proceeding

## Best Practices

1. **Run locally before pushing** - Catch issues early
2. **Fix formatting first** - It's the fastest fix
3. **Don't ignore warnings** - They often indicate real problems
4. **Keep PLT cached** - Add `priv/plts/` to .gitignore
5. **Run full suite before PR** - Don't rely only on CI

## Environment Variables

```bash
# Run in test environment
MIX_ENV=test mix dialyzer

# Skip dialyzer if building PLT takes too long locally
mix format && mix compile --warnings-as-errors && mix credo --strict && mix test
```

## Exit Codes

- 0: All checks passed
- Non-zero: At least one check failed (stops at first failure with &&)

## Integration with Git Hooks

If using BMAD git hooks, these checks run automatically on:
- pre-commit: Full quality gate
- pre-push: Quick validation

## Troubleshooting

**PLT build fails:**
```bash
# Clean and rebuild
rm -rf _build priv/plts
mix deps.get
mix dialyzer --plt
```

**Tests fail in CI but pass locally:**
- Check MIX_ENV (should be test)
- Verify database is created: `MIX_ENV=test mix ecto.create`
- Check for async test conflicts

**Credo reports too many issues:**
- Start with formatting and compilation
- Fix high-priority issues first
- Consider configuring .credo.exs to match team preferences

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->