fosmvvm-viewmodel-test-generator

# FOSMVVM ViewModel Test Generator Generate test files for ViewModels following FOSMVVM testing patterns. ## Conceptual Foundation > For full architecture context, see [FOSMVVMArchitecture.md](../../docs/FOSMVVMArchitecture.md#testing-support) | [OpenClaw reference]({baseDir}/references/FOSMVVMArchitecture.md) ViewModel testing in FOSMVVM verifies three critical aspects: 1. **Codable round-trip** - ViewModel encodes and decodes without data loss 2. **Versioning stability** - Structure hasn't changed unexpectedly 3. **Multi-locale translations** - All `@LocalizedString` properties have values in all supported locales The `LocalizableTestCase` protocol provides infrastructure that tests all three in a single call. --- ## When to Use This Skill - Creating tests for new ViewModels - Adding test coverage to existing ViewModels - Verifying localization completeness across locales - Testing ViewModels with embedded/nested child ViewModels - Verifying `@LocalizedSubs` substitution behavior ## What This Skill Generates | File | Location | Purpose | |------|----------|---------| | `{Name}ViewModelTests.swift` | `Tests/{Target}Tests/Localization/` | Test suite conforming to `LocalizableTestCase` | | `{Name}ViewModel.yml` | `Tests/{Target}Tests/TestYAML/` | YAML translations for test (if needed) | --- ## The Testing Pattern ### Standard Pattern (Most Tests) For most ViewModels, a single line provides complete coverage: ```swift @Test func dashboardViewModel() throws { try expectFullViewModelTests(DashboardViewModel.self) } ``` This verifies: - Codable encoding/decoding - Versioned ViewModel stability - Translations exist for all locales (en, es by default) **This is sufficient for the vast majority of ViewModel tests.** ### Extended Pattern (Specific Formatting Verification) When testing specific formatting behavior (substitutions, compound strings), add locale-specific assertions: ```swift @Test func greetingWithSubstitution() throws { try expectFullViewModelTests(GreetingViewModel.self) // Verify specific substitution behavior let vm: GreetingViewModel = try .stub() .toJSON(encoder: encoder(locale: en)) .fromJSON() #expect(try vm.welcomeMessage.localizedString == "Welcome, John!") } ``` This is optional - use only when verifying specific formatting techniques. --- ## LocalizableTestCase Protocol Test suites conform to `LocalizableTestCase` to access testing infrastructure: ```swift import FOSFoundation @testable import FOSMVVM import FOSTesting import Foundation import Testing @testable import {ViewModelsTarget} @Suite("My ViewModel Tests") struct MyViewModelTests: LocalizableTestCase { let locStore: LocalizationStore init() throws { self.locStore = try Self.loadLocalizationStore( bundle: {ViewModelsTarget}.resourceAccess, resourceDirectoryName: "" ) } } ``` The `{ViewModelsTarget}.resourceAccess` is the resource accessor defined when creating the ViewModels SPM target (via `FOSResourceAccessor` build tool plugin). ### What LocalizableTestCase Provides | Property/Method | Purpose | |-----------------|---------| | `locStore` | Required - the localization store | | `locales` | Optional - locales to test (default: en, es) | | `encoder(locale:)` | Creates a localizing JSONEncoder | | `en`, `es`, `enGB`, `enUS` | Locale constants | ### Testing Methods | Method | Use When | |--------|----------| | `expectFullViewModelTests(_:)` | **Primary** - complete ViewModel testing | | `expectTranslations(_:)` | Translation-only verification | | `expectFullFieldValidationModelTests(_:)` | Testing FieldValidationModel types | | `expectFullFormFieldTests(_:)` | Testing FormField instances | | `expectCodable(_:encoder:)` | Codable round-trip only | | `expectVersionedViewModel(_:encoder:)` | Versioning stability only | --- ## YAML Requirements ### ViewModels with @LocalizedString Every ViewModel with `@LocalizedString` properties needs YAML entries: ```swift @ViewModel public struct DashboardViewModel: RequestableViewModel { @LocalizedString public var pageTitle // Needs YAML entry @LocalizedString public var emptyMessage // Needs YAML entry public let itemCount: Int // No YAML needed } ``` ```yaml # DashboardViewModel.yml en: DashboardViewModel: pageTitle: "Dashboard" emptyMessage: "No items yet" es: DashboardViewModel: pageTitle: "Tablero" emptyMessage: "No hay elementos todavía" ``` ### Embedded ViewModels When a ViewModel contains child ViewModels, all types in the hierarchy need YAML entries: ```swift @ViewModel public struct BoardViewModel: RequestableViewModel { @LocalizedString public var title public let cards: [CardViewModel] // Child ViewModel } @ViewModel public struct CardViewModel { @LocalizedString public var cardTitle } ``` Both `BoardViewModel` and `CardViewModel` need YAML entries (can be in same or separate files). ### Private Test ViewModels When tests define private ViewModel structs for testing specific scenarios, those also need YAML: ```swift // In test file private struct TestParentViewModel: ViewModel { @LocalizedString var title let children: [TestChildViewModel] } private struct TestChildViewModel: ViewModel { @LocalizedString var label } ``` Add entries to a test YAML file for these private types. --- ## How to Use This Skill **Invocation:** /fosmvvm-viewmodel-test-generator **Prerequisites:** - ViewModel structure understood from conversation context - Localization properties identified (@LocalizedString, @LocalizedSubs, etc.) - YAML localization files exist or will be created - Child ViewModels identified (if any) **Workflow integration:** This skill is used when adding test coverage for ViewModels. The skill references conversation context automatically—no file paths or Q&A needed. Typically follows fosmvvm-viewmodel-generator. ## Pattern Implementation This skill references conversation context to determine test structure: ### ViewModel Analysis From conversation context, the skill identifies: - **ViewModels to test** (from prior discussion or codebase) - **Localization requirements** (@LocalizedString properties) - **Child ViewModels** (embedded within parent) - **Substitution behavior** (@LocalizedSubs needing specific verification) ### YAML Coverage Check Verifies completeness: - **ViewModel YAML entries** (all @LocalizedString properties) - **Child ViewModel entries** (nested types) - **Locale coverage** (en, es, or project-specific locales) ### Test File Generation Creates test suite with: - LocalizableTestCase conformance - Localization store initialization - expectFullViewModelTests() calls for each ViewModel - Optional specific formatting tests (substitutions, compound strings) ### Context Sources Skill references information from: - **Prior conversation**: ViewModels discussed or recently created - **ViewModel code**: If Claude has read ViewModel files into context - **YAML files**: From codebase analysis of existing localizations - **Test patterns**: From existing test files in project --- ## File Templates See [reference.md](reference.md) for complete file templates. --- ## Common Scenarios ### Testing a Single Top-Level ViewModel ```swift @Test func dashboardViewModel() throws { try expectFullViewModelTests(DashboardViewModel.self) } ``` ### Testing Multiple Related ViewModels ```swift @Test func boardViewModels() throws { try expectFullViewModelTests(BoardViewModel.self) try expectFullViewModelTests(ColumnViewModel.self) try expectFullViewModelTests(CardViewModel.self) } ``` ### Testing with Custom Locales ```swift var locales: Set<Locale> { [en, es, enGB] } // Override default @Test func multiLocaleViewModel() throws { try expectFullViewModelTests(MyViewModel.self) // Tests en, es, AND en-GB } ``` ### Testing Substitution Behavior ```swift @Test func greetingSubstitutions() throws { try expectFullViewModelTests(GreetingViewModel.self) let vm: GreetingViewModel = try .stub(userName: "Alice") .toJSON(encoder: encoder(locale: en)) .fromJSON() #expect(try vm.welcomeMessage.localizedString == "Welcome, Alice!") } ``` ### Testing Embedded ViewModels ```swift @Test func parentWithChildren() throws { // Tests parent AND verifies children can be encoded/decoded try expectFullViewModelTests(ParentViewModel.self) // Optionally verify specific child values let vm: ParentViewModel = try .stub() .toJSON(encoder: encoder(locale: en)) .fromJSON() #expect(try vm.children[0].label.localizedString == "Child 1") } ``` --- ## Troubleshooting ### "Missing Translation" Error ``` FOSLocalizableError: _pageTitle -- Missing Translation -- en ``` **Cause:** YAML entry missing for a `@LocalizedString` property. **Fix:** Add the property to the YAML file: ```yaml en: MyViewModel: pageTitle: "Page Title" # Add this ``` ### "Is pending localization" Error **Cause:** The ViewModel wasn't encoded with a localizing encoder. **Fix:** Ensure using `encoder(locale:)` or `expectFullViewModelTests()`. ### Test Passes But Translations Seem Wrong **Cause:** YAML values exist but may have typos or wrong content. **Fix:** Add specific assertions to verify exact values: ```swift let vm = try .stub().toJSON(encoder: encoder(locale: en)).fromJSON() #expect(try vm.title.localizedString == "Expected Value") ``` --- ## Naming Conventions | Concept | Convention | Example | |---------|------------|---------| | Test suite | `{Feature}ViewModelTests` | `DashboardViewModelTests` | | Test file | `{Feature}ViewModelTests.swift` | `DashboardViewModelTests.swift` | | YAML file | `{ViewModelName}.yml` | `DashboardViewModel.yml` | | Test method | `{viewModelName}()` or descriptive | `dashboardViewModel()` | --- ## See Also - [FOSMVVMArchitecture.md - Testing Support](../../docs/FOSMVVMArchitecture.md#testing-support) - Architecture overview - [fosmvvm-viewmodel-generator](../fosmvvm-viewmodel-generator/SKILL.md) - For creating ViewModels - [fosmvvm-fields-generator](../fosmvvm-fields-generator/SKILL.md) - For form validation testing - [reference.md](reference.md) - Complete file templates --- ## Version History | Version | Date | Changes | |---------|------|---------| | 1.0 | 2025-01-02 | Initial skill | | 1.1 | 2026-01-19 | Updated LocalizableTestCase example to use {ViewModelsTarget}.resourceAccess pattern. | | 1.2 | 2026-01-24 | Update to context-aware approach (remove file-parsing/Q&A). Skill references conversation context instead of asking questions or accepting file paths. |