Add test for deeply mixed Combine/Join nesting case

Co-authored-by: tarekgh <[email protected]>

Author: Copilot

src/Microsoft.CodeAnalysis.NetAnalyzers/tests/Microsoft.CodeAnalysis.NetAnalyzers.UnitTests/Microsoft.NetCore.Analyzers/Performance/CollapseMultiplePathOperationsTests.cs

@@ -380,6 +380,23 @@ public void M()
         string path = Path.Combine(Path.Join(Path.Combine(""a"", ""b""), ""c""), ""d"");
     }
 }
+";
+            await VerifyCS.VerifyAnalyzerAsync(csCode);
+        }
+
+        [Fact]
+        public async Task NoDiagnostic_DeeplyMixedCombineAndJoinNesting()
+        {
+            var csCode = @"
+using System.IO;
+
+public class Test
+{
+    public void M()
+    {
+        string path = Path.Combine(Path.Join(Path.Combine(Path.Combine(""a"", ""b""), ""c""), ""d""), ""e"");
+    }
+}
 ";
             await VerifyCS.VerifyAnalyzerAsync(csCode);
         }