FakeManualImplementation.kt

interface NoteApi {
    suspend fun uploadNote(note: Note): Result
    suspend fun fetchAllNotes(): List<Note>
}

class RealNoteApi: NoteApi {
    override suspend fun uploadNote(note: Note): Result {
        //Real impl
    }

    override suspend fun fetchAllNotes(): List<Note> {
        //Real impl
    }
}

class FakeNoteApi: NoteApi {
    private val notes = mutableListOf<Note>()
    
    override suspend fun uploadNote(note: Note): Result {
        notes.add(note)
        
        return Result.Success
    }

    override suspend fun fetchAllNotes(): List<Note> {
        return notes
    }
}