Mason Brick Development Skill

Mason Brick Development Skill

This skill guides the creation, modification, and removal of Mason bricks, ensuring test coverage and CI workflow integration.

When to Use

Trigger this skill when:

• Creating a new Mason brick template
• Updating an existing brick's structure or variables
• Removing a brick from the project
• User asks to "create a brick", "add a mason template", "update brick", or "remove brick"

Project Structure

Bricks are organized in three locations:

bricks/                    # Mason template definitions
├── brick_name/
│   ├── brick.yaml         # Brick configuration and variables
│   ├── __brick__/         # Template files with Mustache syntax
│   └── hooks/             # Optional pre/​post generation hooks

test_bricks/               # Brick tests (one folder per brick)
├── brick_name/
│   └── brick_name_test.dart

.github/​workflows/
└── brick-test.yml         # Parallel CI jobs for each brick

Creating a New Brick

Step 1: Create Brick Directory

mkdir -p bricks/​new_brick/​__brick__

Step 2: Create brick.yaml

name: new_brick
description: Description of what this brick generates
version: 0.1.0+1

environment:
  mason: ^0.1.1

vars:
  name:
    type: string
    description: The name for the generated component
    prompt: What is the name?

  # Add more variables as needed
  optional_var:
    type: boolean
    description: Optional feature flag
    default: true

Step 3: Create Template Files

In __brick__/, create files using Mustache syntax:

__brick__/
├── {{name.snakeCase()}}/
│   ├── lib/
│   │   └── {{name.snakeCase()}}.dart
│   ├── pubspec.yaml
│   └── README.md

Use these Mustache helpers:

• {{name}} - raw value
• {{name.snakeCase()}} - snake_case
• {{name.pascalCase()}} - PascalCase
• {{name.camelCase()}} - camelCase
• {{name.paramCase()}} - param-case
• {{#flag}}...{{/​flag}} - conditional block
• {{^flag}}...{{/​flag}} - inverted conditional

Step 4: Create Brick Test

Create test_bricks/​new_brick/​new_brick_test.dart:

import 'dart:io';
import 'package:mason/​mason.dart';
import 'package:path/​path.dart' as path;
import 'package:test/​test.dart';

void main() {
  group('New Brick Tests', () {
    late Directory tempDir;

    setUp(() async {
      tempDir = await Directory.systemTemp.createTemp('new_brick_test_');
    });

    tearDown(() async {
      if (await tempDir.exists()) {
        await tempDir.delete(recursive: true);
      }
    });

    test('generates correct structure', () async {
      final brick = Brick.path(path.join('..', '..', 'bricks', 'new_brick'));

      final generator = await MasonGenerator.fromBrick(brick);
      await generator.generate(
        DirectoryGeneratorTarget(tempDir),
        vars: {'name': 'test_name'},
      );

      // Verify generated files exist
      final file = File(path.join(tempDir.path, 'test_name', 'pubspec.yaml'));
      expect(await file.exists(), isTrue);
    });

    // Add more tests for different variable combinations
  });
}

Step 5: Add Workflow Job

Add a new job to .github/​workflows/​brick-test.yml:

  new-brick:
    name: Test new_brick
    runs-on: ubuntu-latest
    steps:
      - uses: actions/​checkout@v6

      - uses: flutter-actions/​setup-flutter@v4

      - name: Cache dependencies
        uses: actions/​cache@v5
        with:
          path: |
            ~/​.pub-cache
            .dart_tool
          key: ${{ runner.os }}-pub-${{ hashFiles('**/​pubspec.lock') }}
          restore-keys: ${{ runner.os }}-pub-

      - name: Install tools
        run: dart pub global activate melos

      - name: Prepare project
        run: |
          melos run prepare
          mason get

      - name: Test new_brick brick
        run: dart run test_bricks/​new_brick/​new_brick_test.dart

Step 6: Register Brick

Add to root mason.yaml:

bricks:
  new_brick:
    path: bricks/​new_brick

Then run mason get to register.

Updating an Existing Brick

When modifying a brick:

1. Update brick.yaml if adding/​removing variables
2. Update template files in __brick__/
3. Update tests in test_bricks/​brick_name/ to cover changes
4. Run test locally: dart run test_bricks/​brick_name/​brick_name_test.dart
5. Increment version in brick.yaml

Removing a Brick

When removing a brick, update all three locations:

1. Remove brick directory: rm -rf bricks/​brick_name
2. Remove test directory: rm -rf test_bricks/​brick_name
3. Remove workflow job from .github/​workflows/​brick-test.yml
4. Remove from mason.yaml
5. Update CLAUDE.md if the brick was documented

Testing Locally

# Register bricks
mason get

# Test a specific brick
dart run test_bricks/​brick_name/​brick_name_test.dart

# Test brick generation manually
mason make brick_name -o /​tmp/​test_output --var1=value1

Existing Bricks Reference

Checklist

When creating/​updating a brick:

• brick.yaml has name, description, version, and vars
• Template files use correct Mustache syntax
• Test file exists in test_bricks/​brick_name/
• Tests cover main generation paths
• Workflow job added/​updated in brick-test.yml
• Brick registered in mason.yaml
• Run mason get to verify registration
• Run test locally before committing