step3/api/QuestionsApi.Tests/FlashcardClozeParserTests.cs

using QuestionsApi.Services.Flashcards;
using Xunit;

namespace QuestionsApi.Tests;

public sealed class FlashcardClozeParserTests
{
    [Fact]
    public void Parse_ExtractsAnswerAndHint()
    {
        var deletions = FlashcardClozeParser.Parse("The capital of France is {{c1::Paris::country capital}}.");

        var deletion = Assert.Single(deletions);
        Assert.Equal(1, deletion.Number);
        Assert.Equal("Paris", deletion.Answer);
        Assert.Equal("country capital", deletion.Hint);
    }

    [Fact]
    public void Parse_WithoutHint_LeavesHintNull()
    {
        var deletions = FlashcardClozeParser.Parse("{{c1::Paris}}");

        Assert.Null(Assert.Single(deletions).Hint);
    }

    [Fact]
    public void DistinctClozeNumbers_DeduplicatesRepeatedNumbersAndSorts()
    {
        var text = "{{c2::b}} some text {{c1::a}} more {{c1::a-again}} {{c3::c}}";

        var numbers = FlashcardClozeParser.DistinctClozeNumbers(text);

        Assert.Equal([1, 2, 3], numbers);
    }

    [Theory]
    [InlineData("no cloze markers here")]
    [InlineData("{{c0::invalid, number must be >= 1}}")]
    [InlineData("{{cX::not a number}}")]
    [InlineData("{{c1::}}")]
    public void HasValidCloze_IsFalse_ForMalformedOrMissingMarkers(string text)
    {
        Assert.False(FlashcardClozeParser.HasValidCloze(text));
    }

    [Fact]
    public void HasValidCloze_IsTrue_WhenAtLeastOneValidMarkerExists()
    {
        Assert.True(FlashcardClozeParser.HasValidCloze("prefix {{c1::answer}} suffix"));
    }

    [Fact]
    public void RenderFront_HidesTargetNumber_RevealsOthers()
    {
        var text = "{{c1::Paris}} is the capital of {{c2::France}}";

        var front1 = FlashcardClozeParser.RenderFront(text, 1);
        var front2 = FlashcardClozeParser.RenderFront(text, 2);

        Assert.Equal("[...] is the capital of France", front1);
        Assert.Equal("Paris is the capital of [...]", front2);
    }

    [Fact]
    public void RenderFront_UsesHintWhenPresent()
    {
        var text = "{{c1::Paris::capital city}} is in France";

        var front = FlashcardClozeParser.RenderFront(text, 1);

        Assert.Equal("[capital city] is in France", front);
    }

    [Fact]
    public void RenderBack_RevealsAllAnswers()
    {
        var text = "{{c1::Paris}} is the capital of {{c2::France::hint}}";

        var back = FlashcardClozeParser.RenderBack(text, 1);

        Assert.Equal("Paris is the capital of France", back);
    }

    [Fact]
    public void Parse_SupportsMultilineClozeContent()
    {
        var text = "Line one\n{{c1::multi\nline\nanswer}}\nLine two";

        var deletion = Assert.Single(FlashcardClozeParser.Parse(text));

        Assert.Equal("multi\nline\nanswer", deletion.Answer);
    }
}