Prerequisites
Steps to reproduce
In .NET 9, a breaking change introduced empty string support to environment variables. As of that change, the only way to remove an environment variable is to set it to null via Environment.SetEnvironmentVariable(). I've confirmed this behavior in .NET 9 with C#.
PR #24133 introduced .NET 9, and the above breaking change, into PowerShell v7.5.0-preview.4.
However, setting an environment variable to $null in [Environment]::SetEnvironmentVariable() now sets the environment variable to an empty string, instead of the expected behavior of unsetting the environment variable. Notably, setting the variable to null via the ENV provider works as expected.
The below tests explain the expected behavior, but Environment Variable.System.Environment.Should unset environment variables with null fails because [Environment]::GetEnvironmentVariable() yields an empty string '' instead of $null.
Describe 'Environment Variable' {
Context 'System.Environment' {
It 'Should unset environment variables with null' {
[System.Environment]::SetEnvironmentVariable('TEST_DOTNETAPI_NULL', $null)
[System.Environment]::GetEnvironmentVariable('TEST_DOTNETAPI_NULL') | Should -Be $null
}
# See breaking change in .NET 9:
# https://learn.microsoft.com/en-us/dotnet/core/compatibility/core-libraries/9.0/empty-env-variable
It 'Should set environment variables with empty string' -Skip:([Environment]::Version.Major -lt 9) {
[System.Environment]::SetEnvironmentVariable('TEST_DOTNETAPI_EMPTY', '')
[System.Environment]::GetEnvironmentVariable('TEST_DOTNETAPI_EMPTY') | Should -Be ''
}
}
Context 'ENV Drive' {
It 'Should unset environment variables with null' {
$ENV:TEST_ENV_NULL = $null
$ENV:TEST_ENV_NULL | Should -Be $null
}
# See breaking change in .NET 9:
# https://learn.microsoft.com/en-us/dotnet/core/compatibility/core-libraries/9.0/empty-env-variable
It 'Should set environment variables with empty string' -Skip:([Environment]::Version.Major -lt 9) {
$ENV:TEST_ENV_EMPTY = ''
$ENV:TEST_ENV_EMPTY | Should -Be ''
}
}
}Expected behavior
Actual behavior
> Invoke-Pester .\EnvironmentVariable.Tests.ps1
Starting discovery in 1 files.
Discovery found 4 tests in 7ms.
Running tests.
[-] Environment Variable.System.Environment.Should unset environment variables with null 4ms (3ms|0ms)
Expected $null, but got <empty>.
at [System.Environment]::GetEnvironmentVariable('TEST_DOTNETAPI_NULL') | Should -Be $null, C:\EnvironmentVariableTest\EnvironmentVariable.Tests.ps1:6
at <ScriptBlock>, C:\EnvironmentVariableTest\EnvironmentVariable.Tests.ps1:6
Tests completed in 60ms
Tests Passed: 3, Failed: 1, Skipped: 0, Inconclusive: 0, NotRun: 0Error details
No response
Environment data
Name Value
---- -----
PSVersion 7.5.0-rc.1
PSEdition Core
GitCommitId 7.5.0-rc.1
OS Microsoft Windows 10.0.22631
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0Visuals
No response
Prerequisites
Steps to reproduce
In .NET 9, a breaking change introduced empty string support to environment variables. As of that change, the only way to remove an environment variable is to set it to
nullviaEnvironment.SetEnvironmentVariable(). I've confirmed this behavior in .NET 9 with C#.PR #24133 introduced .NET 9, and the above breaking change, into PowerShell v7.5.0-preview.4.
However, setting an environment variable to
$nullin[Environment]::SetEnvironmentVariable()now sets the environment variable to an empty string, instead of the expected behavior of unsetting the environment variable. Notably, setting the variable to null via the ENV provider works as expected.The below tests explain the expected behavior, but
Environment Variable.System.Environment.Should unset environment variables with nullfails because[Environment]::GetEnvironmentVariable()yields an empty string''instead of$null.Expected behavior
All four tests passActual behavior
Error details
No response
Environment data
Visuals
No response