Flutter Fixtures Core #

Core interfaces and domain models for the Flutter Fixtures library. This package provides the foundational abstractions that enable extensible fixture-based mocking.

🎯 Purpose #

This package defines the core contracts and data models used by all Flutter Fixtures implementations. Use this package when:

• Creating custom data providers (database, file system, network, etc.)
• Extending the Flutter Fixtures ecosystem with new data source functionality
• Building libraries that need fixture-based mocking capabilities

📦 What's Included #

Interfaces #

• DataQuery<Input, Output>: Abstract interface for querying data sources
• DataSelectorView: Interface for fixture selection components
• FixtureSelector: Mixin providing fixture selection functionality

Data Models #

• FixtureCollection: Container for multiple fixture response options
• FixtureDocument: Individual fixture response definition

Selection Strategies #

• DataSelectorType: Sealed class defining fixture selection strategies
  • Random(): Randomly select from available fixtures
  • Default(): Use the fixture marked as default
  • Pick(): Let user choose through UI

🚀 Quick Start #

Add to your pubspec.yaml:

dependencies:
  flutter_fixtures_core: ^0.1.0

🛠️ Creating Custom Data Providers #

Implement the DataQuery interface to create custom data sources:

import 'package:flutter_fixtures_core/flutter_fixtures_core.dart';

class DatabaseDataQuery implements DataQuery<String, Map<String, dynamic>> {
  final Database database;

  DatabaseDataQuery(this.database);

  @override
  Future<Map<String, dynamic>?> find(String query) async {
    // Query your database
    final result = await database.query('fixtures', where: 'query = ?', whereArgs: [query]);
    return result.isNotEmpty ? result.first : null;
  }

  @override
  Future<FixtureCollection?> parse(Map<String, dynamic> source) async {
    // Parse database result into fixture collection
    return FixtureCollection(
      description: source['description'],
      items: (source['options'] as List).map((item) =>
        FixtureDocument(
          identifier: item['id'],
          description: item['description'],
          defaultOption: item['is_default'] ?? false,
          data: item['response_data'],
        )
      ).toList(),
    );
  }

  @override
  Future<Map<String, dynamic>?> data(FixtureDocument document) async {
    // Return the response data
    return document.data;
  }

  @override
  Future<FixtureDocument?> select(
    FixtureCollection fixture,
    DataSelectorView? view,
    DataSelectorType selector,
  ) async {
    // Use the FixtureSelector mixin for standard selection logic
    return switch (selector) {
      Pick() => await view?.pick(fixture),
      Default() => fixture.items.firstWhere((item) => item.defaultOption ?? false),
      Random() => fixture.items[Random().nextInt(fixture.items.length)],
    };
  }
}

🧩 Using the FixtureSelector Mixin #

The FixtureSelector mixin provides standard fixture selection logic:

class MyDataProvider with FixtureSelector implements DataQuery<String, Map<String, dynamic>> {
  @override
  Future<Map<String, dynamic>?> find(String input) async {
    // Your find implementation
  }

  @override
  Future<FixtureCollection?> parse(Map<String, dynamic> source) async {
    // Your parse implementation
  }

  @override
  Future<Map<String, dynamic>?> data(FixtureDocument document) async {
    // Your data implementation
  }

  // select() method is provided by the FixtureSelector mixin
}

📋 Data Model Reference #

FixtureCollection #

Container for multiple fixture response options:

final collection = FixtureCollection(
  description: 'User API responses',
  items: [
    FixtureDocument(
      identifier: 'success',
      description: '200 Success',
      defaultOption: true,
      data: {'users': [...]},
    ),
    // ... more fixtures
  ],
);

FixtureDocument #

Individual fixture response definition:

final document = FixtureDocument(
  identifier: 'success',           // Unique identifier
  description: '200 Success',      // Human-readable description
  defaultOption: true,             // Whether this is the default choice
  data: {'users': [...]},          // Inline response data
  dataPath: 'users_large.json',    // Or path to external data file
);

DataSelectorType #

Fixture selection strategies:

// Always use default fixture
final defaultSelector = DataSelectorType.defaultValue();

// Randomly select fixture
final randomSelector = DataSelectorType.random();

// Let user choose via UI (requires DataSelectorView implementation)
final pickSelector = DataSelectorType.pick();

DataSelectorView #

Interface for implementing fixture selection mechanisms:

abstract class DataSelectorView {
  Future<FixtureDocument?> pick(FixtureCollection fixture);
}

This interface is implemented by UI packages to provide user-driven fixture selection. The core package defines the contract, while implementation packages (like flutter_fixtures_ui) provide concrete implementations.

🔗 Integration #

This package provides the foundation for:

• flutter_fixtures_dio: Dio HTTP client implementation
• flutter_fixtures_ui: UI components for fixture selection
• flutter_fixtures: Complete library with all components

Use this package directly when building custom data providers or extending the Flutter Fixtures ecosystem.

📚 Examples #

For complete examples and usage patterns, see the Flutter Fixtures repository.

🤝 Contributing #

Contributions are welcome! Please read our contributing guide.

📄 License #

MIT License - see the LICENSE file for details.