Configures Pester v5 for testing PowerShell CLIs, scripts, and cmdlets - Describe/Context/It blocks, Should assertions, Mock for isolating external dependencies, BeforeAll/BeforeEach setup hooks, Invoke-Pester with PesterConfiguration for tags, code coverage, and NUnit/JUnit XML output in CI. Use when the unit-under-test is a PowerShell script, function, or CLI tool invoked from pwsh on Windows or cross-platform.