PR Summary

• Replace $PSDefaultParameterValues with $global:PSDefaultParameterValues to correctly restore skipping settings.
• Skip FileSystem Provider Extended tests on Linux because Hidden flag is not supported on Linux in .Net 5 Preview. The tests should be fixed in follow PR.
• Pending two Linux tests because of .Net 5.0 Preview bug System.Diagnostics.Process.ProcessName returning incorrect information on Linux with .NET 5 dotnet/runtime#33673.
  (PowerShell process name is ConsoleHost mai instead of pwsh)
• (Tracking issue Process.Parent property is null on Linux if the process name contains a space #12908) Pending one Linux test because of PowerShell bug manifested due to mentioned .Net bug
  

  PowerShell/src/System.Management.Automation/CoreCLR/CorePsPlatform.cs

  Lines 972 to 985 in 5ef69e8

  	// read /proc/<pid>/stat
  	// 4th column will contain the ppid, 92 in the example below
  	// ex: 93 (bash) S 92 93 2 4294967295 ...
  	var path = $"/proc/{pid}/stat";
  	try
  	{
  	var stat = System.IO.File.ReadAllText(path);
  	var parts = stat.Split(' ', 5);
  	if (parts.Length < 5)
  	{
  	return invalidPid;
  	}
  	return Int32.Parse(parts[3]);

  
  Since a process names contains a space ( ConsoleHost mai) the split returns additional extra element and we get wrong value with parts[3].

PR Context

I discovered that CIs skip silently many tests which run after the Clipboard tests.

I have more general concern - I saw that tests was skipped on Linux but not on Windows and MacOS and I don't understand how this can be. My concern is that there is a bug. I hope MSFT can investigate this.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Experimental feature(s) needed
    • Experimental feature name(s):
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed:
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and enumerated concerns in the summary. This may include:
    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode (which runs in a different PS Host).
    • Impact on Completions (both in the console and in editors) - one of PowerShell's most powerful features.
    • Impact on PSScriptAnalyzer (which provides linting & formatting in the editor extensions).
    • Impact on EditorSyntax (which provides syntax highlighting with in VSCode, GitHub, and many other editors).