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Get Started Free →github/pester-migration
Pester migration skill for upgrading PowerShell Pester test suites across major versions — v3→v4, v4→v5, and v5→v6. Covers the Discovery/Run two-phase model, moving setup into BeforeAll, $PSScriptRoot vs $MyInvocation, mock changes (Assert-MockCalled → Should -Invoke, removed fall-through), Invoke-Pester parameters → PesterConfiguration, data-driven -ForEach/-TestCases, and the v6 breaking changes.
Passed 20 of 21 test cases with the skill, and 15 of 21 without it.
and 5 more in the full report
5 fixed16 passed either way1 still failing0 broke
Tokens, turns and time describe resource use, not a dollar price.
One of 4 test cases the skill fixed. Same model, same prompt, with and without the skill.
We are planning to upgrade our test suite from Pester 5 to Pester 6. What PowerShell runtime version requirements apply to running Pester 6?
| Checked | Without skill | With skill |
|---|---|---|
| The response states that Pester 6 requires Windows PowerShell 5.1 or PowerShell 7.4+. | Missed | Passed |
The instructions your model reads when the skill loads.
Pester is the test framework for PowerShell. Test files end in *.Tests.ps1 and use
Describe / Context / It blocks with Should assertions. This skill upgrades an existing
suite from one major Pester version to the next and gets it green again.
Mental model: each major jump has a different character. v3→v4 is mostly a syntax rename. v4→v5 is a fundamental runtime change (the Discovery/Run split) and is the hard one. v5→v6 is largely backwards-compatible — a handful of previously-deprecated things now throw. Migrate one major at a time; never skip a version.
Detailed, symptom-driven guides live in references/ — load the one(s) for the jump you are doing.
| Reference | When to load |
|---|---|
| v3-to-v4.md | Should Be → Should -Be, Contain → FileContentMatch, Assert-VerifiableMocks → Assert-VerifiableMock, array-assertion edge cases. |
| v4-to-v5.md | The big one. Discovery/Run phases, BeforeAll setup, $PSScriptRoot, BeforeDiscovery, -ForEach, mock scoping, Should -Throw wildcards, Invoke-Pester → New-PesterConfiguration. |
| v5-to-v6.md | PowerShell 5.1/7.4+ only, per-file discovery+run, empty -ForEach throws, duplicate setup blocks throw, name <...> templates evaluate, Assert-MockCalled removed, mocks no longer fall through, code-coverage tracer, legacy Invoke-Pester params removed. |
Canonical source: the official migration guides at https://pester.dev/docs/migrations/ — this skill mirrors them. When in doubt, prefer the website.
Find the installed version(s) and the version the tests were written for. These can differ.
# Installed Pester version(s) on this machine
Get-Module Pester -ListAvailable | Select-Object Name, Version, Path
# Version currently imported in the session
(Get-Module Pester).Version
Tell the source version from the test code with these heuristics:
You see in *.Tests.ps1 / build scripts | Suite was written for |
|---|
test cases passed, vs 15 / 21 without
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