This specific test needs to be permanently disabled for Android I think.
<test name="System.IO.IsolatedStorage.Tests.HelperTests.GetDataDirectory(scope: Machine)" type="System.IO.IsolatedStorage.Tests.HelperTests" method="GetDataDirectory" time="0.0380145" result="Fail">
<failure exception-type="System.IO.IOException">
<message><![CDATA[System.IO.IOException : Read-only file system]]></message>
<stack-trace><![CDATA[ at System.IO.FileSystem.CreateDirectory(String fullPath) in System.Private.CoreLib.dll:token 0x600553a+0x1a2
at System.IO.Directory.CreateDirectory(String path) in System.Private.CoreLib.dll:token 0x60053e6+0x2d
at System.Environment.GetFolderPathCore(SpecialFolder folder, SpecialFolderOption option) in System.Private.CoreLib.dll:token 0x60002b0+0x65
at System.Environment.GetFolderPath(SpecialFolder folder, SpecialFolderOption option) in System.Private.CoreLib.dll:token 0x600029a+0x73
at System.IO.IsolatedStorage.Helper.GetDataDirectory(IsolatedStorageScope scope) in /_/src/libraries/System.IO.IsolatedStorage/src/System/IO/IsolatedStorage/Helper.Win32Unix.cs:line 25
at System.IO.IsolatedStorage.Tests.HelperTests.GetDataDirectory(IsolatedStorageScope scope) in /_/src/libraries/System.IO.IsolatedStorage/tests/System/IO/IsolatedStorage/HelperTests.cs:line 47
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) in System.Private.CoreLib.dll:token 0x6004b15+0x6a]]></stack-trace>
</failure>
This specific test needs to be permanently disabled for Android I think.