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powershellpester

Is there a way to mock an $? return using Pester?

I'm writing tests for a PowerShell application, using Pester.

I have been able to create mocks for most functions, but I haven't been able to mock a function returning the $? variable. I'm currently using it to evaluate the returns from AWS CLI commands.

This is, for example, to mock a failing AWS CLI command return.

Any thoughts?

Solution

  • We created an auxiliary function and passed the $? value.

    function Test-LastExitCodeIsFalse ($last_exit) {
    if ($last_exit) {
       return $false
    }
    $true
}

    And a usage being

    aws s3 <an aws command>
if (Test-LastExitCodeIsFalse($?)) {
   throw "AWS Exception"
}

    Using Pester, then we just mock the Test-LastExitCodeIsFalse function to return false. And we have a unit test with a failing AWS instance :)