fix(vscode): persist the post-processed Cobertura document before the coverage-threshold assertion (#565)

[drmoisan]

Suggested title

fix(vscode): persist the post-processed Cobertura document before the coverage-threshold assertion (#565)

Summary

• scripts/vscode/Invoke-MSTestWithCoverage.ps1 previously called Assert-CoberturaLineCoverageThreshold before Set-Content persisted the post-processed Cobertura XML, so a failing (sub-threshold) run threw before the judged document was ever written to disk, leaving the raw, un-post-processed dotnet-coverage output at the -CoverageOutput path instead.
• Fix is a pure two-statement reorder inside Invoke-MSTestWithCoverageMain: Set-Content now runs immediately after $processedXmlContent is computed and before Assert-CoberturaLineCoverageThreshold is called. No logic, threshold value, or message text changed.
• Adds one new Pester regression test to tests/scripts/vscode/Invoke-MSTest.RunSettings.Tests.ps1 proving Set-Content is invoked exactly once before the threshold assertion can throw on a sub-threshold run.
• This branch was cut before sibling issue Bug: coverage-cobertura-mstest-powershell-tooling-defects #733 (already merged to main) refactored this same file, splitting Assert-CoberturaLineCoverageThreshold out into a new file, scripts/vscode/Invoke-MSTestWithCoverage.Threshold.ps1. The branch was reconciled against the current main, the defect was re-confirmed still present at the drifted line numbers, and the fix was executed and verified against the reconciled tree.
• Threshold value (80%) and message text are unchanged and independently confirmed unmodified in both Invoke-MSTestWithCoverage.Helpers.ps1 and the relocated Invoke-MSTestWithCoverage.Threshold.ps1 (empty diffs against main for both files).
• 6/6 acceptance criteria in spec.md verified and checked off; zero blocking findings in policy-audit, code-review, and feature-audit.

Why

Only the failure path was affected — a passing run always wrote the correct document. But the failure path is exactly when someone reads the artifact on disk to diagnose a coverage shortfall, and what they found was a document with different numbers than the one that produced the failure message (absolute paths, unmerged third-party packages, duplicate classes, and the double-counted line totals that issue #441 had already corrected). A failed gate also left behind an artifact that, if fed to any downstream consumer, silently reported the pre-#441 inflated denominator. Issue #563 (a separate, unrelated contradiction in the threshold value) is explicitly out of scope for this fix, which touches statement order only.

What Changed

Core logic:

• scripts/vscode/Invoke-MSTestWithCoverage.ps1 — swapped the Set-Content and Assert-CoberturaLineCoverageThreshold calls inside Invoke-MSTestWithCoverageMain (net +2/-2 lines).

Tests:

• tests/scripts/vscode/Invoke-MSTest.RunSettings.Tests.ps1 — added one new It to the existing Describe 'Invoke-MSTestWithCoverageMain' block (net +8 lines), inserted between the pre-existing 'fails when the search root cannot be found' test and the sibling-issue-Bug: coverage-cobertura-mstest-powershell-tooling-defects #733-added '.claude worktree' exclusion test.

Docs/evidence:

• docs/features/active/2026-09-02-invoke-mstestwithcoverage-threshold-before-setcontent-565/ — issue, spec, research, atomic plan, full Phase 0-6 evidence trail, and policy-audit/code-review/feature-audit artifacts.

Architecture / How It Fits Together

Invoke-MSTestWithCoverageMain collects coverage via dotnet-coverage, post-processes the raw Cobertura XML for Koverage compatibility (ConvertTo-KoverageCoberturaXml), and previously validated the resulting line-rate before writing it to disk. The fix only reorders when the write happens relative to the validation; Assert-CoberturaLineCoverageThreshold remains a pure read-and-throw function with no side effect that could observe or be observed by Set-Content, so the reorder is behaviorally safe under both the passing and failing case.

Verification

Completed (from evidence trail):

• RED before / GREEN after: pre-fix simulation showed the new test failing (Set-Content invoked 0 times before the throw); post-fix run showed 28/28 tests passed in the target file.
• Full PowerShell suite (10 files, 93 tests): 93 passed, 0 failed, 0 skipped.
• PoshQC format: no rewrites needed on either owned file.
• PSScriptAnalyzer: 0 diagnostics on either owned file (matches baseline).
• Coverage on scripts/vscode/Invoke-MSTestWithCoverage.ps1: 90.09% before and after (no regression).
• git diff against main confirmed empty for both Invoke-MSTestWithCoverage.Helpers.ps1 and Invoke-MSTestWithCoverage.Threshold.ps1 (threshold value/message untouched).
• feature-review: policy-audit PASS, code-review PASS (0 blocking), feature-audit PASS (6/6 AC verified).

Recommended (CI):

• PowerShell workflow(s) covering scripts/vscode/** and tests/scripts/vscode/**.

Backward Compatibility / Migration Notes

None. No function signature, parameter, output format, or configuration surface changed. Passing runs (coverage at or above 80%) are unaffected because both statements always executed in that case; only the failing-run artifact-on-disk behavior changes, and only for the better (it now matches the document that produced the failure).

Risks and Mitigations

• Risk: none identified beyond the reordered two statements themselves — this is a minimal, self-contained fix confined to a single production file plus one test file.
• Mitigation / rollback: the change is a direct two-line swap; rollback is a straightforward revert of the diff.

Review Guide

Suggested order:

1. scripts/vscode/Invoke-MSTestWithCoverage.ps1 — the actual fix (4-line diff).
2. tests/scripts/vscode/Invoke-MSTest.RunSettings.Tests.ps1 — the new regression test (8-line diff).
3. docs/features/active/2026-09-02-invoke-mstestwithcoverage-threshold-before-setcontent-565/spec.md — acceptance criteria and their check-off state.
4. Remaining files are evidence artifacts (baseline/QA-gate/regression-testing captures) and the three review artifacts (policy-audit, code-review, feature-audit); skim for the pass/fail signal in each rather than reading line by line.

Follow-ups

• Issue Coverage threshold contradiction remains: CLAUDE.md/csharp.md say 80%, general-unit-test.md/quality-tiers.md say 85%/75%, and two live gates disagree #563 (threshold value contradiction) remains open and is deliberately out of scope for this fix.

GitHub Auto-close

• Closes Invoke-MSTestWithCoverage.ps1 asserts coverage threshold before Set-Content, leaving the raw un-post-processed Cobertura on disk when the gate fails #565