get-childitem env: fails on Windows when an environment variable is defined twice, cased differently #6305
Description
The problem:
get-childitem env: fails on Windows when an environment variable exists twice, each instance cased differently.
The scenario:
On Windows, set the environment variable NPM_CONFIG_PATH to control where the npm cache is created. And use npm to run unit tests, use powershell within a unit test, and from powershell invoke get-childitem env:. Note, it is common to use npm test to build and test a nodejs project.
It appears npm internally creates environment variables to manage state, and a lower-case variable npm_config_path is created. When powershell is invoked from the unit test, the environment variables NPM_CONFIG_PATH and npm_config_path are both set.
Steps to reproduce
On Windows, tested with npm v5.6.0 in my PATH.
Write-Host "******************** SETTING NPM_CONFIG_PATH ********************"
$null = mkdir env-test
cd env-test
$env:NPM_CONFIG_PATH = $PWD
Write-Host "******************** CREATING PACKAGE.JSON ********************"
& npm init --force --yes
Write-Host "******************** MODIFYING PACKAGE.JSON ********************"
$package = Get-Content package.json | ConvertFrom-Json
$package.scripts.test = "pwsh -command Get-ChildItem env:"
Set-Content -LiteralPath package.json -Encoding UTF8 -Value (ConvertTo-Json -InputObject $package -Depth 99)
Get-Content package.json
Write-Host "******************** TESTING ENV PS DRIVE, VIA NPM ********************"
& npm testExpected behavior
PowerShell should gracefully handle the duplicate environment variable. The set builtin in cmd.exe handles it gracefully. .NET Environment.GetEnvironmentVariables() handles it gracefully.
Actual behavior
Get-ChildItem fails with "An item with the same key has already been added. Key: NPM_CONFIG_PATH"
Environment data
> $PSVersionTable
Name Value
---- -----
PSVersion 6.0.1
PSEdition Core
GitCommitId v6.0.1
OS Microsoft Windows 10.0.16299
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0