step3/api/QuestionsApi.Tests/FlashcardImportExportModelTests.cs

using System.Text.Json;
using QuestionsApi.Models;
using QuestionsApi.Services.Flashcards;
using Xunit;

namespace QuestionsApi.Tests;

public sealed class FlashcardImportExportModelTests
{
    [Fact]
    public void JsonExport_RoundTrips_NotesCardsAndReviewHistory()
    {
        var export = new FlashcardJsonExport
        {
            SchemaVersion = 1,
            Settings = new FlashcardSettings { UserId = "user-1", NewCardsPerDay = 20, ReviewsPerDay = 200 },
            Decks = [new FlashcardDeck { Id = "deck-1", UserId = "user-1", Name = "Cardio", IsDefault = true }],
            Notes =
            [
                new FlashcardJsonExportNote
                {
                    Note = new FlashcardNote
                    {
                        Id = "note-1", UserId = "user-1", DeckId = "deck-1", StableId = "stable-1",
                        Type = FlashcardTypes.Cloze, Prompt = "{{c1::Paris}} is the capital of France",
                        Tags = ["geography"]
                    },
                    Cards =
                    [
                        new FlashcardSchedule
                        {
                            Id = "card-1", UserId = "user-1", NoteId = "note-1", Variant = 1,
                            State = FlashcardScheduleStates.Review, Stability = 12.3, Difficulty = 4.5,
                            DueUtc = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc)
                        }
                    ],
                    ReviewLogs =
                    [
                        new FlashcardReviewLog
                        {
                            Id = "log-1", UserId = "user-1", CardId = "card-1", Rating = FlashcardRatings.Good,
                            ReviewedUtc = new DateTime(2025, 12, 31, 0, 0, 0, DateTimeKind.Utc)
                        }
                    ],
                    Images = [new FlashcardJsonExportImage { AssetId = "asset-1", FileName = "x.png", ContentType = "image/png", Base64Bytes = Convert.ToBase64String([1, 2, 3]) }]
                }
            ]
        };

        var json = JsonSerializer.Serialize(export);
        var roundTripped = JsonSerializer.Deserialize<FlashcardJsonExport>(json);

        Assert.NotNull(roundTripped);
        var note = Assert.Single(roundTripped!.Notes);
        Assert.Equal("stable-1", note.Note.StableId);
        Assert.Equal(FlashcardTypes.Cloze, note.Note.Type);
        var card = Assert.Single(note.Cards);
        Assert.Equal(1, card.Variant);
        Assert.Equal(12.3, card.Stability);
        var log = Assert.Single(note.ReviewLogs);
        Assert.Equal(FlashcardRatings.Good, log.Rating);
        var image = Assert.Single(note.Images);
        Assert.Equal([1, 2, 3], Convert.FromBase64String(image.Base64Bytes));
    }

    [Fact]
    public void Fingerprint_IsStable_ForSameTypePromptAndAnswer_IgnoringSurroundingWhitespace()
    {
        var a = FlashcardNoteStore.Fingerprint(FlashcardTypes.Basic, "  What is 2+2?  ", "4");
        var b = FlashcardNoteStore.Fingerprint(FlashcardTypes.Basic, "What is 2+2?", "4");

        Assert.Equal(a, b);
    }

    [Fact]
    public void Fingerprint_DiffersWhenAnswerDiffers()
    {
        var a = FlashcardNoteStore.Fingerprint(FlashcardTypes.Basic, "What is 2+2?", "4");
        var b = FlashcardNoteStore.Fingerprint(FlashcardTypes.Basic, "What is 2+2?", "five");

        Assert.NotEqual(a, b);
    }

    [Fact]
    public void Fingerprint_DiffersByType_ForSamePromptAndAnswer()
    {
        var basic = FlashcardNoteStore.Fingerprint(FlashcardTypes.Basic, "text", "text");
        var cloze = FlashcardNoteStore.Fingerprint(FlashcardTypes.Cloze, "text", "text");

        Assert.NotEqual(basic, cloze);
    }
}