List existing test cases in Pester script

Question

Folks,

I'd like to use Pester to automate the cmdlet testing. Is there a way to list available test cases (such as describe blocks) without actual executing? Is there a command like this? Thanks.

mclayton mclayton · Accepted Answer · 2019-08-29T19:02:10

In general, no.

The Describe, Context and It keywords might look like a static DSL, but they're actually just PowerShell cmdlets that take a string and a script block as a parameter - the tests themselves are only "materialized" (for want of a better word) when the script runs.

As an extreme example, consider this test script. How many tests are there in it?

Describe 'Weird Test Cases' {

    Context 'Context' {

        for( $i = 0; $i -lt (Get-Random -Maximum 25); $i++ )
        {
            It "Test #$($i)" {
                $true | Should -Be $true;
            }
        }

        if( $false )
        {
            It "Should never execute" {
                $true | Should -Be $true;
            }
        }

    }

}

In a more simple example you could potentially use the built-in PowerShell Parser Class to parse your script and look for invocations of cmdlets called It, but that would be very brittle and likely to give wrong results in a lot of cases. It would also be a lot of work to consider test filters like the Tag and ExcludeTag parameters on Invoke-Pester.

However, if you want to know how many tests were run afterwards you can use the PassThru switch wth Invoke-Pester which will return an xml report on the tests that ran and their results, and you could process that to find out how many were executed.

List existing test cases in Pester script

1 Answers