Initial commit.

PerfectNumbers.Core.Tests/StringBuilderPoolTests.cs

@@ -0,0 +1,36 @@
+using FluentAssertions;
+using Xunit;
+
+namespace PerfectNumbers.Core.Tests;
+
+public class StringBuilderPoolTests
+{
+    [Fact]
+    [Trait("Category", "Fast")]
+    public void Rent_ReturnsClearedBuilder()
+    {
+        var sb = StringBuilderPool.Rent();
+
+        sb.Length.Should().Be(0);
+
+        StringBuilderPool.Return(sb);
+    }
+
+    [Fact]
+    [Trait("Category", "Fast")]
+    public void Return_AllowsReuseOfBuilder()
+    {
+        var sb = StringBuilderPool.Rent();
+        sb.Append("data");
+
+        StringBuilderPool.Return(sb);
+
+        var reused = StringBuilderPool.Rent();
+
+        reused.Should().BeSameAs(sb);
+        reused.Length.Should().Be(0);
+
+        StringBuilderPool.Return(reused);
+    }
+}
+