Fixed line endings in the reflection folder and tests on Windows (#1192)

app/Tests/Tools/PluginSystem/I18NSourceScannerTests.cs

@@ -101,7 +101,8 @@ public sealed class I18NSourceScannerTests
 
         var texts = I18NSourceScanner.FindTexts(SOURCE, "Notice.cs", []);
 
-        Assert.That(texts.Select(text => text.Text), Is.EqualTo(new[] { "## Welcome!\n\nThe first paragraph." }));
+        // The scanner keeps the line endings of the checkout, as the compiler does, and the collector makes them equal:
+        Assert.That(texts.Select(text => I18NKeyHash.NormalizeLineEndings(text.Text)), Is.EqualTo(new[] { "## Welcome!\n\nThe first paragraph." }));
     }
 
     [Test]

app/Tests/Tools/StringBuilderExtensionsTests.cs

@@ -0,0 +1,46 @@
+using System.Globalization;
+using System.Text;
+
+using SharedTools;
+
+namespace AIStudio.Tests.Tools;
+
+/// <summary>
+/// Checks that AppendLineLF ends every line with LF, whatever the system.
+/// </summary>
+/// <remarks>
+/// StringBuilder.AppendLine writes CR LF on Windows. These tests would show it there, while on macOS and Linux they
+/// pass with both.
+/// </remarks>
+[TestFixture]
+public sealed class StringBuilderExtensionsTests
+{
+    [Test]
+    public void EveryKindOfLineEndsWithLf()
+    {
+        var number = 4711;
+        var text = new StringBuilder()
+            .AppendLineLF("Erste Zeile")
+            .AppendLineLF()
+            .AppendLineLF($"Nummer {number}")
+            .AppendLineLF(null)
+            .ToString();
+
+        Assert.That(text, Is.EqualTo("Erste Zeile\n\nNummer 4711\n\n"));
+    }
+
+    [Test]
+    public void AnInterpolatedTextGoesIntoTheSameBuilderInItsPlace()
+    {
+        var value = 1.5;
+        var builder = new StringBuilder("Anfang ");
+
+        var returned = builder.AppendLineLF($"{value.ToString(CultureInfo.InvariantCulture)} und {"Text"}").Append("Ende");
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(returned, Is.SameAs(builder));
+            Assert.That(builder.ToString(), Is.EqualTo("Anfang 1.5 und Text\nEnde"));
+        }
+    }
+}