Fix infinite loop in exception formatting when exceptions have cyclic references #3972
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… references The GetFormattedExceptionMessage method in ExceptionHelper.cs recursively traverses the inner exceptions of an exception to build a formatted error message string. However, it did not handle the case where the inner exceptions have a cyclic reference, causing an infinite loop. This change fixes that issue by keeping track of the exceptions seen during traversal in a HashSet. If an exception is encountered again, it breaks out of the loop and appends a "[Cyclic Exception Reference]" message to the output, avoiding the infinite recursion. The key changes are: Introduce a HashSet seenExceptions to keep track of exceptions encountered so far. Check if the current exception has already been seen. If so, append a "[Cyclic Exception Reference]" message and break out of the loop. If the current exception hasn't been seen, add it to the seenExceptions set and continue processing as before. A new test class ExceptionHelperTests has also been added with two test methods: GetFormattedExceptionMessage_WithCyclicExceptions_ShouldNotLoopInfinitely - Verifies that cyclic exceptions are handled correctly and don't cause infinite loops. GetFormattedExceptionMessage_WithNoCyclicExceptions_ShouldFormatNormally - Ensures that the normal formatting still works as expected for non-cyclic exceptions. This fixes microsoft#1234 Files changed: src/Adapter/MSTest.TestAdapter/Execution/ExceptionHelper.cs test/UnitTests/MSTestAdapter.UnitTests/Execution/ExceptionHelperTests.cs
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@microsoft-github-policy-service agree |
Fix formatting
campersau
reviewed
Oct 27, 2024
Co-authored-by: campersau <[email protected]>
Evangelink
reviewed
Oct 28, 2024
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| [TestClass] | ||
| public class ExceptionHelperTests |
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We are not using MSTest to test MSTest for some historical reason.
Suggested change
| [TestClass] | |
| public class ExceptionHelperTests | |
| public sealed class ExceptionHelperTests : TestContainer |
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| [TestMethod] | ||
| public void GetFormattedExceptionMessage_WithCyclicExceptions_ShouldNotLoopInfinitely() |
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| [TestMethod] | |
| public void GetFormattedExceptionMessage_WithCyclicExceptions_ShouldNotLoopInfinitely() | |
| public void GetFormattedExceptionMessage_WithCyclicExceptions_ShouldNotLoopInfinitely() |
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| [TestMethod] | ||
| public void GetFormattedExceptionMessage_WithNoCyclicExceptions_ShouldFormatNormally() |
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| [TestMethod] | |
| public void GetFormattedExceptionMessage_WithNoCyclicExceptions_ShouldFormatNormally() | |
| public void GetFormattedExceptionMessage_WithNoCyclicExceptions_ShouldFormatNormally() |
| for (Exception? curException = ex; | ||
| curException != null; | ||
| curException = curException.InnerException) | ||
| { | ||
| if (!seenExceptions.Add(curException)) | ||
| { | ||
| result.Append(" ---> [Cyclic Exception Reference]"); |
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Evangelink
reviewed
Oct 28, 2024
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I still don't understand this. An exception can't have a cyclical inner exception reference without using reflection to hack it (unless someone can give me source code to prove me wrong?) And that would hang on the throw anyway so this wouldn't solve that? |
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Good point! I assumed that the throw was good and it was hanging inside MSTest but that's the throw that's causing exception so nothing to do on MSTest side. Thanks @thomhurst |
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The
GetFormattedExceptionMessagemethod inExceptionHelper.csrecursively traverses the inner exceptions of an exception to build a formatted error message string. However, it didn't handle the case where the inner exceptions have a cyclic reference, causing an infinite loop.This change fixes that issue by keeping track of the exceptions seen during traversal in a HashSet. If an exception is encountered again, it breaks out of the loop and appends a "[Cyclic Exception Reference]" message to the output, avoiding the infinite recursion.
The key changes are:
This fixes #3971