Add test

Author: theletterf

tests/Elastic.Markdown.Tests/TextFormat/IrregularWhitespaceTest.cs

@@ -0,0 +1,119 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using Elastic.Documentation.Diagnostics;
+using Elastic.Markdown.Tests.Inline;
+using FluentAssertions;
+
+namespace Elastic.Markdown.Tests.TextFormat;
+
+public class IrregularWhitespaceTest(ITestOutputHelper output) : InlineTest(output,
+"""
+# Heading with no-break space\u00A0character
+
+This is a paragraph with some\u2002en space and\u200Bzero width space.
+
+## Subheading with\u3000ideographic space
+
+* List item with\u00A0no-break space
+* Another item
+
+```csharp
+// Code with\u00A0no-break space
+var x = 1;
+```
+
+> Blockquote with\u2003em space
+"""
+)
+{
+    [Fact]
+    public void DetectsIrregularWhitespaceInHeading()
+    {
+        var diagnostics = Collector.Diagnostics
+            .Where(d => d.Line == 1)
+            .Where(d => d.Message.Contains("U+00A0"))
+            .ToList();
+            
+        diagnostics.Should().HaveCount(1);
+        diagnostics[0].Severity.Should().Be(Severity.Warning);
+    }
+
+    [Fact]
+    public void DetectsIrregularWhitespaceInParagraph()
+    {
+        var diagnostics = Collector.Diagnostics
+            .Where(d => d.Line == 3)
+            .Where(d => d.Message.Contains("irregular whitespace"))
+            .ToList();
+            
+        diagnostics.Should().HaveCountGreaterThanOrEqualTo(2);
+        
+        // Verify en space detection
+        diagnostics.Should().Contain(d => d.Message.Contains("U+2002"));
+        
+        // Verify zero width space detection
+        diagnostics.Should().Contain(d => d.Message.Contains("U+200B"));
+    }
+
+    [Fact]
+    public void DetectsIrregularWhitespaceInSubheading()
+    {
+        var diagnostics = Collector.Diagnostics
+            .Where(d => d.Line == 5)
+            .Where(d => d.Message.Contains("U+3000"))
+            .ToList();
+            
+        diagnostics.Should().HaveCount(1);
+        diagnostics[0].Severity.Should().Be(Severity.Warning);
+    }
+
+    [Fact]
+    public void DetectsIrregularWhitespaceInListItem()
+    {
+        var diagnostics = Collector.Diagnostics
+            .Where(d => d.Line == 7)
+            .Where(d => d.Message.Contains("U+00A0"))
+            .ToList();
+            
+        diagnostics.Should().HaveCount(1);
+        diagnostics[0].Severity.Should().Be(Severity.Warning);
+    }
+
+    [Fact]
+    public void DetectsIrregularWhitespaceInCodeBlock()
+    {
+        var diagnostics = Collector.Diagnostics
+            .Where(d => d.Line == 11)
+            .Where(d => d.Message.Contains("U+00A0"))
+            .ToList();
+            
+        diagnostics.Should().HaveCount(1);
+        diagnostics[0].Severity.Should().Be(Severity.Warning);
+    }
+
+    [Fact]
+    public void DetectsIrregularWhitespaceInBlockquote()
+    {
+        var diagnostics = Collector.Diagnostics
+            .Where(d => d.Line == 15)
+            .Where(d => d.Message.Contains("U+2003"))
+            .ToList();
+            
+        diagnostics.Should().HaveCount(1);
+        diagnostics[0].Severity.Should().Be(Severity.Warning);
+    }
+    
+    [Fact]
+    public void GeneratesProperWarningMessage()
+    {
+        var noBreakSpaceWarning = Collector.Diagnostics
+            .FirstOrDefault(d => d.Message.Contains("U+00A0"));
+            
+        noBreakSpaceWarning.Should().NotBeNull();
+        noBreakSpaceWarning!.Message.Should()
+            .Contain("Irregular whitespace character detected: U+00A0 (No-Break Space (NBSP))")
+            .And.Contain("may impair Markdown rendering");
+    }
+}