Get-ChildItem -Name and Get-ChildItem -Include / -Exclude unexpectedly follow symlinks with -Recurse

[mklement0]

PowerShell Core (unlike Windows PowerShell) by default is supposed to not follow symlinks (symbolic links) to directories during recursive traversal with Get-ChildItem -Recurse (you can opt in with -FollowSymlink).

While this generally works, using the -Name or -Include / -Exclude switches unexpectedly causes symlinks to be followed even without the -FollowSymlink switch.

Note: On Windows, the tests currently fail categorically, due to an unrelated bug: #9127

Steps to reproduce (on Unix)

Run the following Pester tests:

Describe "Get-ChildItem: symlink-following tests" {
  BeforeAll {
    Push-Location TestDrive:/
    # Create a directory with 2 files in it. 
    $null = New-Item -Type Directory someDir
    1..2 | % { $_ > "someDir/$_.txt" }
    # Create a symlink to that directory, as a sibling.
    New-Item -Type SymbolicLink someDirLink -Target someDir
  }
  AfterAll {
    Pop-Location
  }
  
  It "Get-ChildItem -Recurse doesn't follow dir. symlinks." {
    (Get-ChildItem -File -Recurse).Count | Should -Be 2
  }

  It "Get-ChildItem -Recurse -Path with a wildcard doesn't follow dir. symlinks." {
    (Get-ChildItem -File -Recurse -Path *).Count | Should -Be 2
  }

  It "Get-ChildItem -Recurse -Name doesn't follow dir. symlinks." {
    (Get-ChildItem -File -Recurse -Name).Count | Should -Be 2
  }

  It "Get-ChildItem -Recurse -Include doesn't follow dir. symlinks." {
    (Get-ChildItem -File -Recurse -Include *).Count | Should -Be 2
  }

  It "Get-ChildItem -Recurse -Exclude doesn't follow dir. symlinks." {
    (Get-ChildItem -File -Recurse -Exclude nosuch).Count | Should -Be 2
  }
  
}

Expected behavior

All tests should pass.

Actual behavior

The last 3 tests fail.

Environment data

PowerShell Core 6.2.0-rc.1

[ChrSchultz]

on Windows all tests fails,
Describing Get-ChildItem: symlink-following tests
[-] Get-ChildItem -Recurse doesn't follow dir. symlinks. 6ms Expected 2, but got 3.
15: (Get-ChildItem -File -Recurse).Count | Should -Be 2
at <ScriptBlock>, C:\Users\ic-sc\test.ps1: line 15
[-] Get-ChildItem -Recurse -Path with a wildcard doesn't follow dir. symlinks. 5ms Expected 2, but got 3.
19: (Get-ChildItem -File -Recurse -Path *).Count | Should -Be 2 at <ScriptBlock>, C:\Users\ic-sc\test.ps1: line 19
[-] Get-ChildItem -Recurse -Name doesn't follow dir. symlinks. 7ms Expected 2, but got 3.
23: (Get-ChildItem -File -Recurse -Name).Count | Should -Be 2 at <ScriptBlock>, C:\Users\ic-sc\test.ps1: line 23
[-] Get-ChildItem -Recurse -Include doesn't follow dir. symlinks. 7ms Expected 2, but got 3.
27: (Get-ChildItem -File -Recurse -Include *).Count | Should -Be 2 at <ScriptBlock>, C:\Users\ic-sc\test.ps1: line 27
[-] Get-ChildItem -Recurse -Exclude doesn't follow dir. symlinks. 8ms Expected 2, but got 3.
31: (Get-ChildItem -File -Recurse -Exclude nosuch).Count | Should -Be 2 at <ScriptBlock>, C:\Users\ic-sc\test.ps1: line 31
Tests completed in 146ms
Tests Passed: 0, Failed: 5, Skipped: 0, Pending: 0, Inconclusive: 0

[mklement0]

@ChrSchultz: That is due to an unrelated bug, reported in #9127 - I've added this info to the OP.

[Bertaz]

By changing #L4 New-Item -Type SymbolicLink someDirLink -Target someDir into New-Item -Type SymbolicLink someDirLink -Target .\someDir the tests can ignore the unrelated bug.
That bug is specifically caused by #15161, which was closed as duplicate of the more comprehensive issue #15235. (#9127 is closed as fixed, but was only partially fixed)

Result:

Describing Get-ChildItem: symlink-following tests
  [+] Get-ChildItem -Recurse doesn't follow dir. symlinks. 5ms (4ms|2ms)
  [+] Get-ChildItem -Recurse -Path with a wildcard doesn't follow dir. symlinks. 5ms (4ms|1ms)
  [-] Get-ChildItem -Recurse -Name doesn't follow dir. symlinks. 7ms (7ms|1ms)
   Expected 2, but got 4.
   at (Get-ChildItem -File -Recurse -Name).Count | Should -Be 2, C:\pester\symFollow.Tests.ps1:23
   at <ScriptBlock>, C:\pester\symFollow.Tests.ps1:23
  [-] Get-ChildItem -Recurse -Include doesn't follow dir. symlinks. 8ms (8ms|1ms)
   Expected 2, but got 4.
   at (Get-ChildItem -File -Recurse -Include *).Count | Should -Be 2, C:\pester\symFollow.Tests.ps1:27
   at <ScriptBlock>, C:\pester\symFollow.Tests.ps1:27
  [-] Get-ChildItem -Recurse -Exclude doesn't follow dir. symlinks. 10ms (10ms|1ms)
   Expected 2, but got 4.
   at (Get-ChildItem -File -Recurse -Exclude nosuch).Count | Should -Be 2, C:\pester\symFollow.Tests.ps1:31
   at <ScriptBlock>, C:\pester\symFollow.Tests.ps1:31
Tests completed in 116ms
Tests Passed: 2, Failed: 3, Skipped: 0 NotRun: 0

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has been marked as "No Activity" as there has been no activity for 6 months. It has been closed for housekeeping purposes.