test-data-factory

Test Data Factory

Generate factory helpers that make creating test data effortless. Eliminates boilerplate in test setup so writing tests has zero friction.

When This Skill Activates

Use this skill when the user:

• Has repetitive test setup code
• Asks for "test fixtures" or "test factories" or "sample data"
• Wants to reduce boilerplate in tests
• Says "my tests have too much setup"
• Is building a test suite and needs realistic sample data
• Mentions "builder pattern" for tests

Why Test Factories

// ❌ Without factory — every test repeats this
let item = Item(
    id: UUID(),
    title: "Test Item",
    description: "A test description",
    category: .general,
    createdAt: Date(),
    updatedAt: Date(),
    isFavorite: false,
    tags: [],
    author: User(id: UUID(), name: "Test User", email: "[email protected]")
)

// ✅ With factory — one line, override only what matters
let item = Item.fixture()
let favoriteItem = Item.fixture(isFavorite: true)
let taggedItem = Item.fixture(tags: ["swift", "testing"])

Process

Phase 1: Discover Models

Glob: **/*.swift (in source targets)
Grep: "struct.*:.*Identifiable|class.*:.*Identifiable|@Model"
Grep: "struct.*:.*Codable|struct.*:.*Sendable"

Identify models that appear in test files:

Grep: "let.*=.*Model(" in test targets (manual construction)

Phase 2: Choose Factory Pattern

Ask via AskUserQuestion:

1. Factory style?

   • Static factory methods (simpler, recommended)
   • Builder pattern (more flexible, for complex models)
   • Both

2. Where to add?

   • Test target extension (recommended — keeps production code clean)
   • Shared test helper file

Phase 3: Generate Factories

Pattern 1: Static Factory Extension

// Tests/Factories/Item+Factory.swift

import Foundation
@testable import YourApp

extension Item {
    /// Creates a test fixture with sensible defaults.
    /// Override only the properties relevant to your test.
    static func fixture(
        id: UUID = UUID(),
        title: String = "Test Item",
        description: String = "A test description",
        category: Category = .general,
        createdAt: Date = Date(timeIntervalSince1970: 1_700_000_000),
        updatedAt: Date = Date(timeIntervalSince1970: 1_700_000_000),
        isFavorite: Bool = false,
        tags: [String] = [],
        author: User = .fixture()
    ) -> Item {
        Item(
            id: id,
            title: title,
            description: description,
            category: category,
            createdAt: createdAt,
            updatedAt: updatedAt,
            isFavorite: isFavorite,
            tags: tags,
            author: author
        )
    }

    /// Named fixtures for common test scenarios
    static var sample: Item { .fixture() }
    static var favorite: Item { .fixture(isFavorite: true) }
    static var empty: Item { .fixture(title: "", description: "") }

    /// Collection fixtures
    static var sampleList: [Item] {
        [
            .fixture(id: UUID(), title: "First Item", category: .work),
            .fixture(id: UUID(), title: "Second Item", category: .personal),
            .fixture(id: UUID(), title: "Third Item", category: .general)
        ]
    }
}

extension User {
    static func fixture(
        id: UUID = UUID(),
        name: String = "Test User",
        email: String = "[email protected]"
    ) -> User {
        User(id: id, name: name, email: email)
    }

    static var sample: User { .fixture() }
}