Agent-Skills.md

Agent Skills: Pester `Should -*` → `Should-*` Migration

Experimental (preview) Pester skill for migrating classic Should -Be (v5) assertion syntax to the new Should-* (v6) assertions (note the hyphen, no space), e.g. `Should -Be` -> `Should-Be`, `Should -Not -Be` -> `Should-NotBe`. Tracks Pester 6, which is still a release candidate, so this guidance may change; verified against Pester 6.0.0-rc2. Use when converting Pester v5 assertions to Pester v6 Should-* operators, modernizing a Pester test suite, or when a user asks to migrate, convert, or rewrite `Should -...` calls in .Tests.ps1 / PowerShell files.

UncategorizedID: github/awesome-copilot/pester-should-migration

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github/awesome-copilot
githubLicense: MIT
38,9014,927

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pnpm dlx add-skill https://github.com/github/awesome-copilot/tree/HEAD/skills/pester-should-migration

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skills/pester-should-migration/SKILL.md

Skill Metadata

Name
pester-should-migration
Description
'Experimental (preview) Pester skill for migrating classic Should -Be (v5) assertion syntax to the new Should-* (v6) assertions (note the hyphen, no space), e.g. `Should -Be` -> `Should-Be`, `Should -Not -Be` -> `Should-NotBe`. Tracks Pester 6, which is still a release candidate, so this guidance may change; verified against Pester 6.0.0-rc2. Use when converting Pester v5 assertions to Pester v6 Should-* operators, modernizing a Pester test suite, or when a user asks to migrate, convert, or rewrite `Should -...` calls in .Tests.ps1 / PowerShell files.'

Pester Should -* → Should-* Migration

Convert classic Pester v5 assertions (Should -Be, space then parameter) to the new Pester v6 Should-* assertions (Should-Be, hyphen, no space).

Status: experimental / preview. Verified against Pester 6.0.0-rc2. The classic Should -Be style still works in v6, so migrate incrementally and keep the suite green.

Companion skill. This skill covers the optional move to the new Should-* operators. To upgrade a suite across major Pester versions (v3→v4→v5→v6 — the runtime, mocks, and config), use the separate pester-migration skill. In v6 the classic Should -Be keeps working, so adopting Should-* is independent of any version bump.

When to Use

  • Modernizing a Pester suite to the v6 Should-* assertions.
  • A user asks to migrate / convert / rewrite Should -... calls.
  • You want clearer, type-aware failure messages from the new assertions.

Know This First

  • Both syntaxes work side by side in Pester v6. Migration is optional and can be done one test (or one file) at a time. Nothing breaks if you leave some classic.
  • Requires Pester v6+. The Should-* commands do not exist in v5.
  • Negation is a separate command, not a -Not switch: Should -Not -Be → Should-NotBe. There is no -Not parameter on the new assertions.
  • The actual value still comes from the pipeline ($x | Should-Be 1) or from -Actual (Should-Be -Actual $x -Expected 1). -Because carries over unchanged.
  • Most renames are mechanical, but several have behavior changes you must check by hand — see Gotchas.

Procedure

Step 1 — Find the classic assertions

Search the target for the classic space-separated syntax (the tell is Should -, or Should followed by -Not):

Should -          # any classic operator
Should -Not -     # negated classic operator
Assert-MockCalled # also removed in v6 -> Should-Invoke

Limit the scope to PowerShell test files (*.Tests.ps1, *.ps1).

Step 2 — Apply the mapping

Most-used conversions (full list in references/assertion-map.md):

| Classic (v5) | New (v6) | |---|---| | $x \| Should -Be 1 | $x \| Should-Be 1 | | $x \| Should -Not -Be 1 | $x \| Should-NotBe 1 | | $x \| Should -BeExactly 'A' | $x \| Should-BeString 'A' -CaseSensitive | | $x \| Should -BeGreaterOrEqual 2 | $x \| Should-BeGreaterThanOrEqual 2 | | $x \| Should -BeLessOrEqual 2 | $x \| Should-BeLessThanOrEqual 2 | | $x \| Should -BeLike 'a*' | $x \| Should-BeLikeString 'a*' | | $x \| Should -Match 're' | $x \| Should-MatchString 're' | | $x \| Should -BeOfType [int] | $x \| Should-HaveType ([int]) | | $x \| Should -BeNullOrEmpty | depends — see gotchas (no single equivalent) | | $c \| Should -HaveCount 3 | $c \| Should-BeCollection -Count 3 | | $c \| Should -Contain 2 | $c \| Should-ContainCollection 2 | | { ... } \| Should -Throw 'msg' | { ... } \| Should-Throw -ExceptionMessage 'msg' | | Should -Invoke Get-Thing | Should-Invoke Get-Thing | | Should -InvokeVerifiable | Should-Invoke -Verifiable |

Step 3 — Check the behavioral gotchas (do NOT skip)

These do not translate by a plain rename. Read each before converting:

  1. Case sensitivity. Classic Should -Be is case-insensitive on strings; so is Should-Be. But classic Should -BeExactly (case-sensitive) has no plain equivalent — use Should-BeString -CaseSensitive. (Should-Be is never case-sensitive.) Same pattern for BeLikeExactly → Should-BeLikeString -CaseSensitive and MatchExactly → Should-MatchString -CaseSensitive.
  2. Truthy vs. true. Classic Should -BeTrue / -BeFalse accept any truthy / falsy value (1, 'x', 0, '', $null, @()). The new Should-BeTrue / Should-BeFalse are strict (exactly $true / $false). To preserve the old loose behavior use Should-BeTruthy / Should-BeFalsy. Only use the strict ones when the value really is a boolean.
  3. BeNullOrEmpty has no single equivalent. Pick by intent: $null → Should-BeNull; empty string → Should-BeEmptyString; empty collection → Should-BeCollection -Count 0; broad "falsy" → Should-BeFalsy. The negation Should -Not -BeNullOrEmpty similarly splits into Should-NotBeNull / Should-NotBeEmptyString / Should-NotBeWhiteSpaceString.
  4. Collections. Classic Should -Be also compares arrays; the new Should-Be is a value assertion and errors if -Expected is a collection ("You provided a collection to the -Expected parameter"). Use Should-BeCollection to compare arrays. Should -Contain (single-item membership) → Should-ContainCollection. The new command also takes a collection of expected items and checks they are all present, in the right order (1, 2, 3 | Should-ContainCollection @(1, 2)). For exact, whole-collection equality use Should-BeCollection instead.
  5. Pipeline unwrapping. The pipeline unwraps input: a value assertion sees @(1) as 1 and @() as $null, and a typed collection ([int[]]) is re-collected as [object[]]. When the exact value or concrete collection type matters (e.g. Should-HaveType), pass it with -Actual instead of piping.
  6. No Should-* equivalent. Should -Exist and the Should -FileContentMatch* family have no new counterpart. Either keep the classic assertion, or rewrite with PowerShell: Test-Path $p | Should-BeTrue, (Get-Content $p -Raw) | Should-MatchString 're'.
  7. Should -BeIn direction. No Should-BeIn. Reverse the operands: $value | Should -BeIn $collection → $collection | Should-ContainCollection $value (note the actual/expected swap), or keep the classic form.

Step 4 — Verify

Run the suite and confirm it's still green — the new messages differ, but passes must stay passes:

Invoke-Pester -Path ./tests

If a converted assertion newly fails, re-check the gotchas above (most often #2 truthy/falsy, #3 null-or-empty, or #4 collections).

Step 5 — (Optional) Enforce the new style

Once a suite is fully migrated, switch off the classic syntax so it can't creep back:

$config = New-PesterConfiguration
$config.Should.DisableV5 = $true

With this set, any remaining Should -Be throws and points at the Should-Be form.

Output

Summarize what changed: files touched, count of assertions converted, any classic assertions intentionally left (e.g. Should -Exist), and any conversions that need a human decision (truthy/falsy, null-or-empty, collection semantics).

Reference

  • references/assertion-map.md — full operator-by-operator table with before/after examples and workarounds.
  • Live command reference: https://pester.dev/docs/commands/Should-Be (swap in any Should-* name) for exact parameters and examples.
  • Concepts: https://pester.dev/docs/assertions/should-command (value vs. collection assertions, pipeline vs. -Actual).
  • v5→v6 upgrade guide: https://pester.dev/docs/migrations/v5-to-v6.