Additional Pester tests needed

[devblackops]

Description

Additional integration Pester tests are needed to verify the various psake/InvokeBuild tasks function as expected.

Sub-tasks

🟢 Good First Issues (unit tests, no fixture module needed)

• Tests: Clear-PSBuildOutputFolder #94 Clear-PSBuildOutputFolder
• Tests: Initialize-PSBuild #95 Initialize-PSBuild
• Tests: Test-PSBuildScriptAnalysis #96 Test-PSBuildScriptAnalysis

Integration Tests (require fixture module)

• Tests: Create shared fixture module #97 Create shared fixture module (prerequisite for all below)
• Tests: Build-PSBuildModule #98 Build-PSBuildModule
• Tests: Build-PSBuildMarkdown #99 Build-PSBuildMarkdown
• Tests: Build-PSBuildMAMLHelp #100 Build-PSBuildMAMLHelp
• Tests: Build-PSBuildUpdatableHelp #101 Build-PSBuildUpdatableHelp
• Tests: Test-PSBuildPester #102 Test-PSBuildPester
• Tests: Publish-PSBuildModule #103 Publish-PSBuildModule

Notes

• All new tests target Pester 6.0.0, pinned to an exact version in requirements.psd1 (Pester 5 entered maintenance mode with the 6.0.0 release on 2026-07-07 — see decision comment below)
• Use the classic Should -Be assertion syntax (valid in both Pester 5 and 6), not the new Should-* assertion family, so tests remain trivially backportable to Pester 5.9 if needed
• This decision affects only this repository's own test suite. The shipped module's Pester support contract (Test-PSBuildPester minimum of 5.0.0, manifest RequiredModules) is unchanged
• Shared fixture module lives at tests/fixtures/TestModule/
• Build-PSBuildUpdatableHelp requires Windows (skip on Linux CI runners)