Try to workaround non-deterministic test failures.

ICSharpCode.Decompiler.Tests/CorrectnessTestRunner.cs

@@ -329,8 +329,8 @@ namespace ICSharpCode.Decompiler.Tests
 				
 				Tester.RunAndCompareOutput(testFileName, outputFile.PathToAssembly, decompiledOutputFile.PathToAssembly, decompiledCodeFile);
 				
-				File.Delete(decompiledCodeFile);
-				File.Delete(decompiledOutputFile.PathToAssembly);
+				Tester.RepeatOnIOError(() => File.Delete(decompiledCodeFile));
+				Tester.RepeatOnIOError(() => File.Delete(decompiledOutputFile.PathToAssembly));
 			} finally {
 				if (outputFile != null)
 					outputFile.TempFiles.Delete();
@@ -354,8 +354,8 @@ namespace ICSharpCode.Decompiler.Tests
 
 				Tester.RunAndCompareOutput(testFileName, outputFile.PathToAssembly, decompiledOutputFile.PathToAssembly, decompiledCodeFile);
 
-				File.Delete(decompiledCodeFile);
-				File.Delete(decompiledOutputFile.PathToAssembly);
+				Tester.RepeatOnIOError(() => File.Delete(decompiledCodeFile));
+				Tester.RepeatOnIOError(() => File.Delete(decompiledOutputFile.PathToAssembly));
 			} finally {
 				if (outputFile != null)
 					outputFile.TempFiles.Delete();
@@ -375,9 +375,9 @@ namespace ICSharpCode.Decompiler.Tests
 				decompiledOutputFile = Tester.CompileCSharp(decompiledCodeFile, options);
 				
 				Tester.RunAndCompareOutput(testFileName, outputFile, decompiledOutputFile.PathToAssembly, decompiledCodeFile);
-				
-				File.Delete(decompiledCodeFile);
-				File.Delete(decompiledOutputFile.PathToAssembly);
+
+				Tester.RepeatOnIOError(() => File.Delete(decompiledCodeFile));
+				Tester.RepeatOnIOError(() => File.Delete(decompiledOutputFile.PathToAssembly));
 			} finally {
 				if (decompiledOutputFile != null)
 					decompiledOutputFile.TempFiles.Delete();

ICSharpCode.Decompiler.Tests/Helpers/Tester.VB.cs

@@ -5,6 +5,7 @@ using System.IO;
 using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.VisualBasic;

ICSharpCode.Decompiler.Tests/Helpers/Tester.cs

@@ -518,5 +518,21 @@ namespace ICSharpCode.Decompiler.Tests.Helpers
 				Assert.Fail(b.ToString());
 			}
 		}
+
+		internal static void RepeatOnIOError(Action action, int numTries = 5)
+		{
+			for (int i = 0; i < numTries - 1; i++) {
+				try {
+					action();
+					return;
+				} catch (IOException) {
+				} catch (UnauthorizedAccessException) {
+					// potential virus scanner problem
+				}
+				Thread.Sleep(10);
+			}
+			// If the last try still fails, don't catch the exception
+			action();
+		}
 	}
 }