angreal-patterns

What this skill does

# Angreal Patterns

Common patterns for testing, documenting, and developing angreal tasks.

## Testing Patterns

### Unit Testing Task Functions

```python
# tests/test_build.py
import sys
sys.path.insert(0, ".angreal")
from task_build import build

def test_build_debug_mode():
    result = build(release=False)
    assert result == 0

def test_build_release_mode():
    result = build(release=True)
    assert result == 0
```

### Mocking External Commands

```python
from unittest.mock import patch, MagicMock

def test_run_tests_success():
    with patch("subprocess.run") as mock_run:
        mock_run.return_value = MagicMock(returncode=0)
        from task_test import run_tests
        result = run_tests()
        assert result == 0
```

### Mocking angreal.get_root()

```python
# tests/conftest.py
import pytest
from pathlib import Path

@pytest.fixture
def temp_project(tmp_path):
    """Create temporary project structure."""
    angreal_dir = tmp_path / ".angreal"
    angreal_dir.mkdir()
    (tmp_path / "src").mkdir()
    return tmp_path

@pytest.fixture
def mock_root(temp_project, monkeypatch):
    """Mock get_root() to return .angreal/ directory."""
    import angreal
    angreal_dir = temp_project / ".angreal"
    monkeypatch.setattr(angreal, "get_root", lambda: angreal_dir)
    return temp_project  # Return project root for assertions
```

### Testing Output

```python
def test_task_output(capsys):
    from task_status import status
    status()
    captured = capsys.readouterr()
    assert "Project Status" in captured.out
```

## Development Patterns

### Angreal Debug Logging (`ANGREAL_DEBUG`)

For debugging Angreal itself (task discovery, command registration, argument parsing, template rendering) — independent of any task-internal `-v` flag your task author wired up:

```bash
ANGREAL_DEBUG=true angreal test rust --unit-only
```

`ANGREAL_DEBUG=true` forces debug-level logging from the Angreal runtime and overrides CLI `-v`/`-vv` flags. Output goes to stderr. Use this when a task isn't being discovered, an argument isn't parsing as expected, or a template render fails silently.

In CI, also set `ANGREAL_NO_AUTO_COMPLETION=1` to suppress the auto-install of shell completion on first run.

### Verbose Mode

```python
import angreal

@angreal.command(name="build", about="Build project")
@angreal.argument(name="verbose", short="v", long="verbose",
                  is_flag=True, takes_value=False)
def build(verbose=False):
    if verbose:
        print("Starting build...")

    do_build()

    if verbose:
        print("Build complete!")
```

### Quiet Mode

```python
@angreal.command(name="check", about="Run checks")
@angreal.argument(name="quiet", short="q", long="quiet",
                  is_flag=True, takes_value=False)
def check(quiet=False):
    issues = run_checks()

    if not issues:
        if not quiet:
            print("All checks passed!")
        return 0

    if not quiet:
        for issue in issues:
            print(f"  - {issue}")
    return 1
```

### Dry Run Mode

```python
import angreal
import shutil
import os

@angreal.command(name="clean", about="Clean build artifacts")
@angreal.argument(name="dry_run", short="n", long="dry-run",
                  is_flag=True, takes_value=False)
def clean(dry_run=False):
    project_root = angreal.get_root().parent
    targets = ["dist/", "build/", ".cache/"]

    for target in targets:
        path = project_root / target
        if path.exists():
            if dry_run:
                print(f"Would remove: {path}")
            else:
                print(f"Removing: {path}")
                shutil.rmtree(path)

    if dry_run:
        print("\nDry run - no changes made.")
```

### Progress Indicators

```python
@angreal.command(name="test", about="Run tests")
def test():
    tests = discover_tests()
    for i, test in enumerate(tests, 1):
        print(f"[{i}/{len(tests)}] Running {test}...")
        run_test(test)
    print("All tests complete!")
```

## Subprocess Patterns

### Running Commands in Project Root

```python
import subprocess
import angreal

def run_in_project(cmd, **kwargs):
    """Run command in project root."""
    project_root = angreal.get_root().parent
    defaults = {
        "cwd": project_root,
        "capture_output": True,
        "text": True
    }
    defaults.update(kwargs)
    return subprocess.run(cmd, **defaults)
```

### Streaming Output

```python
@angreal.command(name="test", about="Run tests")
def test():
    project_root = angreal.get_root().parent

    process = subprocess.Popen(
        ["pytest", "-v"],
        cwd=project_root,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        text=True
    )

    for line in process.stdout:
        print(line, end="")

    return process.wait()
```

### Handling Failures

```python
def run_or_fail(cmd, error_msg):
    """Run command, exit on failure."""
    result = subprocess.run(cmd, capture_output=True, text=True)

    if result.returncode != 0:
        print(f"Error: {error_msg}")
        if result.stderr:
            print(result.stderr)
        return 1

    return 0
```

## Error Handling Patterns

### Fail Fast

```python
@angreal.command(name="deploy", about="Deploy application")
def deploy():
    # Check all prerequisites first
    if not check_credentials():
        print("Error: Missing credentials")
        return 1

    if not check_build_exists():
        print("Error: No build. Run 'angreal build' first.")
        return 1

    # Only proceed if everything ready
    do_deploy()
    return 0
```

### Informative Error Messages

```python
def validate_env(env):
    valid = ["development", "staging", "production"]

    if env not in valid:
        print(f"Error: Invalid environment '{env}'")
        print(f"Valid options: {', '.join(valid)}")
        return False

    return True
```

### Environment Variable Checking

```python
import os

@angreal.command(name="deploy", about="Deploy")
def deploy():
    required = ["AWS_ACCESS_KEY_ID", "AWS_SECRET_ACCESS_KEY"]
    missing = [v for v in required if not os.environ.get(v)]

    if missing:
        print("Error: Missing environment variables:")
        for var in missing:
            print(f"  - {var}")
        return 1

    do_deploy()
    return 0
```

## Documentation Patterns

### Documentation Layers

| Layer | Audience | Location |
|-------|----------|----------|
| `about` | CLI users | `--help` output |
| `long_about` | CLI users | Detailed help |
| `help` (args) | CLI users | Argument help |
| `ToolDescription` | AI agents | `angreal tree --long` |
| Docstrings | Developers | Source code |

### Consistent Structure

```python
@angreal.command(
    name="deploy",
    about="Deploy to environment",  # Short for listings
    long_about="""
    Deploy the application to a specified environment.

    Handles: building, uploading, migrations, health checks.

    Supported environments: development, staging, production
    """,  # Detailed for --help
    tool=angreal.ToolDescription("""
        Deploy application to environment.

        ## When to use
        - After tests pass
        - When release is approved

        ## Examples
        ```
        angreal deploy --env staging
        ```
        """, risk_level="destructive")  # For AI agents
)
def deploy():
    """Deploy application. (For developers reading code)"""
    pass
```

## Anti-Patterns to Avoid

### Don't Hardcode Paths

```python
# Bad
config = open("/Users/me/project/config.yaml")

# Good
project_root = angreal.get_root().parent
config = open(project_root / "config.yaml")
```

### Don't Ignore Return Codes

```python
# Bad
subprocess.run(["npm", "install"])
subprocess.run(["npm", "test"])  # Runs even if install failed

# Good
result = subprocess.run(["npm", "install"])
if result.returncode != 0:
    return 1
subprocess.run(["npm", "test"])
```

### Don't Swallow Exceptions

```python
# Bad
try:
    do_something()
except:
    pass

# Good
try:
    do_