Added saving code blocks of every programming language (#1117)

app/Tests/Components/ExportableMarkdownTests.cs

@@ -0,0 +1,65 @@
+using AIStudio.Components;
+using AIStudio.Tools;
+
+using Markdig.Extensions.Mathematics;
+using Markdig.Syntax;
+
+namespace AIStudio.Tests.Components;
+
+/// <summary>
+/// Checks which code blocks of an answer get actions, such as a button to save them.
+/// </summary>
+/// <remarks>
+/// A block finds its file by where it starts. The chat renders the answer with a pipeline of its
+/// own, so the blocks are read the same way here; how an answer cut around a formula keeps its
+/// positions is checked in PlainFileExportTests.
+/// </remarks>
+[TestFixture]
+public sealed class ExportableMarkdownTests
+{
+    [Test]
+    public void EachCodeBlockFindsItsFile()
+    {
+        var answer = Lines(
+            "| Quarter | Revenue |",
+            "|---|---|",
+            "| Q1 | 100 |",
+            string.Empty,
+            "```python",
+            "print(100)",
+            "```",
+            string.Empty,
+            "```html",
+            "<p>100</p>",
+            "```");
+
+        var files = PlainFileExport.ExtractFiles(answer, ',');
+        var foundFiles = Render(answer).Descendants<FencedCodeBlock>().Select(block => ExportableMarkdown.FileAt(files, block.Span.Start));
+
+        Assert.That(foundFiles, Is.EqualTo(new[] { files[1], files[2] }), "The table comes first among the files, but it is no code block.");
+    }
+
+    [Test]
+    public void AFormulaFindsNoFile()
+    {
+        var answer = Lines("1. The energy follows from", string.Empty, "   $$", "   E = mc^2", "   $$");
+
+        var formula = Render(answer).Descendants<MathBlock>().Single();
+
+        Assert.That(ExportableMarkdown.FileAt(PlainFileExport.ExtractFiles(answer, ','), formula.Span.Start), Is.Null, "Markdig reads a formula as a fenced block, but nobody saves a formula as a text file.");
+    }
+
+    [Test]
+    public void ACodeBlockTheModelNeverClosedFindsNoFile()
+    {
+        var answer = Lines("The answer starts normally.", string.Empty, "```python", "def main():");
+
+        var block = Render(answer).Descendants<FencedCodeBlock>().Single();
+
+        Assert.That(ExportableMarkdown.FileAt(PlainFileExport.ExtractFiles(answer, ','), block.Span.Start), Is.Null, "The file would end wherever the answer broke off.");
+    }
+
+    private static MarkdownDocument Render(string answer) => Markdig.Markdown.Parse(answer, Markdown.CHAT_MARKDOWN_PIPELINE);
+
+    private static string Lines(params string[] lines) => string.Join(Environment.NewLine, lines);
+}