René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"get-childitem env: fails on Windows when an environment variable is defined twice, cased differently","articleBody":"The problem:\r\n`get-childitem env:` fails on Windows when an environment variable exists twice, each instance cased differently.\r\n\r\nThe scenario:\r\nOn 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.\r\n\r\nIt 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.\r\n\r\nSteps to reproduce\r\n------------------\r\n\r\nOn Windows, tested with npm v5.6.0 in my PATH.\r\n\r\n```powershell\r\nWrite-Host \"******************** SETTING NPM_CONFIG_PATH ********************\"\r\n$null = mkdir env-test\r\ncd env-test\r\n$env:NPM_CONFIG_PATH = $PWD\r\nWrite-Host \"******************** CREATING PACKAGE.JSON ********************\"\r\n\u0026 npm init --force --yes\r\nWrite-Host \"******************** MODIFYING PACKAGE.JSON ********************\"\r\n$package = Get-Content package.json | ConvertFrom-Json\r\n$package.scripts.test = \"pwsh -command Get-ChildItem env:\"\r\nSet-Content -LiteralPath package.json -Encoding UTF8 -Value (ConvertTo-Json -InputObject $package -Depth 99)\r\nGet-Content package.json\r\nWrite-Host \"******************** TESTING ENV PS DRIVE, VIA NPM ********************\"\r\n\u0026 npm test\r\n```\r\n\r\nExpected behavior\r\n-----------------\r\n\r\nPowerShell should gracefully handle the duplicate environment variable. The `set` builtin in cmd.exe handles it gracefully. .NET `Environment.GetEnvironmentVariables()` handles it gracefully.\r\n\r\nActual behavior\r\n---------------\r\n\r\nGet-ChildItem fails with \\\"An item with the same key has already been added. Key: NPM_CONFIG_PATH\\\"\r\n\r\nEnvironment data\r\n----------------\r\n\r\n```powershell\r\n\u003e $PSVersionTable\r\nName                           Value\r\n----                           -----\r\nPSVersion                      6.0.1\r\nPSEdition                      Core\r\nGitCommitId                    v6.0.1\r\nOS                             Microsoft Windows 10.0.16299\r\nPlatform                       Win32NT\r\nPSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}\r\nPSRemotingProtocolVersion      2.3\r\nSerializationVersion           1.1.0.1\r\nWSManStackVersion              3.0\r\n```\r\n","author":{"url":"https://github.com/ericsciple","@type":"Person","name":"ericsciple"},"datePublished":"2018-03-03T01:55:32.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":15},"url":"https://github.com/6305/PowerShell/issues/6305"}