# Kotlin Di

> Dependency Injection - Hilt, Koin, scopes, testing

- Skill: `majiayu000/kotlin-di` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/kotlin-di`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/kotlin-di/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/kotlin-di

---


# Kotlin DI Skill

Dependency Injection with Hilt and Koin.

## Topics Covered

### Hilt for Android
```kotlin
@HiltAndroidApp
class App : Application()

@Module
@InstallIn(SingletonComponent::class)
object AppModule {
    @Provides @Singleton
    fun provideDatabase(@ApplicationContext context: Context) =
        Room.databaseBuilder(context, AppDatabase::class.java, "app.db").build()

    @Provides
    fun provideUserDao(db: AppDatabase) = db.userDao()
}

@HiltViewModel
class UserViewModel @Inject constructor(
    private val repository: UserRepository
) : ViewModel()
```

### Koin for Multiplatform
```kotlin
val appModule = module {
    single { HttpClient(getEngine()) }
    single { UserRepository(get()) }
    viewModel { UserViewModel(get()) }
}

// Start Koin
startKoin {
    modules(appModule)
}

// Inject
val repository: UserRepository by inject()
```

### Testing with DI
```kotlin
@HiltAndroidTest
class UserViewModelTest {
    @get:Rule val hiltRule = HiltAndroidRule(this)

    @BindValue @JvmField
    val repository: UserRepository = mockk()

    @Inject lateinit var viewModel: UserViewModel

    @Before fun setup() { hiltRule.inject() }
}
```

## Troubleshooting

| Issue | Resolution |
|-------|------------|
| "No binding for..." | Add @Provides or @Binds |
| ViewModel not injected | Use hiltViewModel() in Compose |

## Usage
```
Skill("kotlin-di")
```