System.Runtime.Serialization.Formatters.Tests.BinaryFormatterTests is failing in CI

[jaredpar]

This is blocking our ARM64 runs. Using the RoundtripManyObjectsInOneStream test as a marker to follow the failure.

System.Runtime.Serialization.Formatters.Tests.BinaryFormatterTests.RoundtripManyObjectsInOneStream

Console Log Summary

Appears to be a simple test failure

    System.Runtime.Serialization.Formatters.Tests.BinaryFormatterTests.ValidateAgainstBlobs [FAIL]
      System.NullReferenceException : Object reference not set to an instance of an object.
      Stack Trace:
        /_/src/libraries/System.Runtime.Serialization.Formatters/tests/BinaryFormatterTestData.cs(581,0): at System.Runtime.Serialization.Formatters.Tests.BinaryFormatterTests.SerializableObjects()+MoveNext()
        /_/src/libraries/Common/src/System/Collections/Generic/LargeArrayBuilder.SpeedOpt.cs(117,0): at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
        /_/src/libraries/Common/src/System/Collections/Generic/EnumerableHelpers.Linq.cs(111,0): at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
        /_/src/libraries/System.Linq/src/System/Linq/ToCollection.cs(18,0): at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
        /_/src/libraries/System.Runtime.Serialization.Formatters/tests/BinaryFormatterTestData.cs(81,0): at System.Runtime.Serialization.Formatters.Tests.BinaryFormatterTests.SerializableObjects_MemberData()

Builds

Build	Pull Request	Test Failure Count
#508988	Rolling	1
#509362	Rolling	1
#509595	Rolling	1
#509747	Rolling	1
#509802	Rolling	1
#509865	Rolling	1
#509985	Rolling	1

Configurations

• netcoreapp5.0-Linux-Release-arm64-CoreCLR_release-(Alpine.38.Arm64.Open)Ubuntu.1804.ArmArch.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.8-helix-arm64v8-a45aeeb-20190620184035

Helix Logs

Build	Pull Request	Console	Core	Test Results
#508988	Rolling	console.e86a0bb8.log
#509362	Rolling	console.64a09699.log
#509595	Rolling	console.efc052e0.log
#509747	Rolling	console.4d951fab.log
#509802	Rolling	console.d6fd071b.log
#509865	Rolling	console.6a67a89c.log
#509985	Rolling	console.1c97ea7d.log

[ViktorHofer]

Fixed with #31850