Pester Example

example.Tests.ps1

# Import the stuff you'll be testing.  Could be dot-sourcing a ps1 file here, importing a module, whatever you need.
# If importing a mdoule, make sure you've only got one copy of it imported, or weird things can happen when you start
# to get into mocking.

Remove-Module [S]omeDscResource
Import-Module $PSScriptRoot\SomeDscResource.psm1

# All of the Pester tests in a script must go inside a Describe block; you can mave many Describe blocks in the same
# script, if you like.  Make sure to put the opening brace on the same line as Describe, since this is just a function
# pretending to be a keyword; no assistance from the parser allowing us to put opening braces on their own lines.

Describe 'Test-TargetResource' {

    # Pester tests go into blocks using the 'It' keyword.  If the body of the It block throws a terminating error, it's
    # a failed test.  Otherwise, it succeeds.  Output is ignored.

    It 'Returns false when the item does not exist' {
        $result = Test-TargetResource -Name SomeBogusName -Ensure Present

        # Pester has some built-in assertions; check the about_Should help file.  Aside from giving a slightly more
        # human-readable look to the test script itself, they also give useful output when the test fails, such as
        # the line number in the test file where the Should assertion came from, pointing out exactly where strings
        # differ, that sort of thing.

        $result | Should Be $false
    }

    # Inside a describe, you can optionally define a Context block as a child scope.  This can be used to group
    # similar tests together, and also has an impact on mocking.  (Mocks defined within a Context go out of scope
    # at the end of that Context without affecting the rest of the Describe.)

    Context 'Whatever' {
        It 'Tests something else' {
            $true | Should Be $true
        }
    }
}

# Mocking is a much larger topic, and much of Pester's complexity is there.  It allows you to stub out functions or
# cmdlets so your script can safely be tested without requiring external services or changing anything.

# https://github.com/pester/Pester/wiki/Mocking-with-Pester
# https://github.com/pester/Pester/wiki/Unit-Testing-within-Modules

Line # 2 word four change from 'mdoule' to 'module'