Pester: Cannot access parent scoped variable

Question

I have the following simple test in Pester:

# Name.Tests.ps1

$name = "foo"

Describe "Check name" {
  It "should have the correct value" {
    $name | Should -Be "foo"
  }
}

So when I navigate to the folder containing the test script and run Invoke-Pester, I was expecting the test to pass. Instead, I get the following error:

[-]Check name.should have the correct value. Expected 'foo', but got $null...

Any idea why this fails and why $name is set to null in the It block - shouldn't $name still be set to foo as it's from the parent scope?

@NekoMusume yeah of course `$global:name` and even `$script:name` works but why does it need to be global/script scoped? The examples online don't seem to require that scoping (for eg: https://medium.com/charot/test-arm-templates-using-pester-azure-devops-837b5006c30c) — Khan, Jun 23 '20 at 17:28
You have a typo, `It "should have the correct value` has no ending quotes — Nico Nekoru, Jun 23 '20 at 17:30
This will most likely be because of Pester v5 where tears are pre-discovered which affects how variables are scoped. — Mark Wragg, Jun 23 '20 at 17:41
Ok, so probably a bug then? In any case, any suggestions on how the scoping can be fixed but without resorting to global/script scopes? — Khan, Jun 23 '20 at 17:45

score 7 · Accepted Answer · answered Jun 23 '20 at 18:02

There are new rules to follow for Pester v5 and one of them is the following (https://github.com/pester/Pester#discovery--run):

Put all your code into It, BeforeAll, BeforeEach, AfterAll or AfterEach. Put no code directly into Describe, Context or on the top of your file, without wrapping it in one of these blocks, unless you have a good reason to do so. ... All misplaced code will run during Discovery, and its results won't be available during Run.

So placing the variable assignment in either BeforeAll or BeforeEach within the Describe block should get it working:

Describe "Check name" {
  BeforeAll {
    $name = "foo"
  }
  It "should have the correct value" {
    $name | Should -Be "foo"
  }
}

Thanks to @Mark Wragg for pointing me to the right direction!

score 0 · Answer 2 · answered Jun 23 '20 at 18:43

Here is what i had to do:

#mine only happens during a foreach loop
$names = @("foo", "foo2")

Describe "Check name - all errors" {
    foreach($rec in $names)
    {
        It "should have the correct value" {
            $rec | Should -Be "foo"
        }
    }
}

#this is what i had to do to fix it :(
Describe "Check name - fixed" {
    foreach($rec in $names)
    {
        It "should have the correct value" -TestCases @(
            @{
                rec = $rec
            }
        ) {
            $rec | Should -Be "foo"
        }
    }
}

Pester: Cannot access parent scoped variable

2 Answers2

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