Add generic missed-path coverage reporting (#421)

## Summary
Adds missed-path reporting to the upstream Process-PSModule coverage
flow so consumer repositories do not need repo-local post-coverage jobs.

## Changes
- Extended .github/actions/Get-PesterCodeCoverage to generate a generic
missed-path report from merged coverage data.
- Added a Missed paths section to the code coverage step summary.
- Emit CodeCoverage-MissedPaths.md and CodeCoverage-MissedPaths.json
under CodeCoverage-MissedPaths/.
- Upload CodeCoverage-MissedPaths as an artifact in
.github/workflows/Get-CodeCoverage.yml.

## Notes
- The implementation intentionally avoids repo-specific heuristics and
groups misses by file path and missed line coverage.
- Artifact upload runs with if: always() so the report is still
available when coverage threshold enforcement fails.

---------

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: MariusStorhaug

.github/actions/Get-PesterCodeCoverage/README.md

@@ -9,8 +9,9 @@ This GitHub Action is a part of the [PSModule framework](https://github.com/PSMo
 ## Features
 
 - Combines multiple code coverage reports from parallel test runs
-- Generates markdown/HTML tables showing missed & executed commands
+- Generates Markdown/HTML tables showing missed & executed commands
 - Displays analyzed files and coverage statistics
+- Generates a generic missed-path report (Markdown + JSON)
 - Configurable step summary sections
 - Threshold enforcement for minimum code coverage
 
@@ -40,6 +41,10 @@ This GitHub Action is a part of the [PSModule framework](https://github.com/PSMo
 
 ## Outputs
 
+| Name | Description |
+| ---- | ----------- |
+| `MissedPathReportPath` | Folder path containing `CodeCoverage-MissedPaths.md` and `CodeCoverage-MissedPaths.json` |
+
 ### GitHub Step Summary
 
 The action generates a detailed summary visible in the GitHub Actions UI:
@@ -53,6 +58,7 @@ The action generates a detailed summary visible in the GitHub Actions UI:
    - **Missed Commands**: HTML table with code snippets
    - **Executed Commands**: HTML table with code snippets
    - **Analyzed Files**: List of covered files
+   - **Missed Paths**: Aggregated missed-command counts grouped by file path
 
 Example summary:
 

.github/actions/Get-PesterCodeCoverage/action.yml

@@ -35,6 +35,11 @@ inputs:
     description: The target for code coverage.
     required: false
 
+outputs:
+  MissedPathReportPath:
+    description: Path to the generated missed-path report folder.
+    value: ${{ steps.Get-PesterCodeCoverage.outputs.MissedPathReportPath }}
+
 runs:
   using: composite
   steps:

.github/actions/Get-PesterCodeCoverage/src/main.ps1

@@ -158,6 +158,73 @@ $success = $coveragePercent -ge $coveragePercentTarget
 $statusIcon = $success ? '✅' : '❌'
 $stats | Format-Table -AutoSize | Out-String
 
+$missedPathGroups = $codeCoverage.CommandsMissed |
+    Where-Object { -not [string]::IsNullOrWhiteSpace($_.File) } |
+    Group-Object -Property File |
+    Sort-Object -Property @(
+        @{ Expression = 'Count'; Descending = $true },
+        @{ Expression = 'Name'; Descending = $false }
+    )
+
+$missedPaths = foreach ($group in $missedPathGroups) {
+    $lines = $group.Group |
+        Where-Object { $_.Line -is [ValueType] } |
+        ForEach-Object { [int]$_.Line } |
+        Sort-Object -Unique
+    $missedLines = if ($lines.Count -eq 0) { '' } else { $lines -join ', ' }
+    [pscustomobject]@{
+        Path           = $group.Name
+        MissedCommands = [int]$group.Count
+        MissedLines    = $missedLines
+    }
+}
+
+$missedPathReportPath = 'CodeCoverage-MissedPaths'
+$null = New-Item -Path $missedPathReportPath -ItemType Directory -Force
+
+$missedPathReport = [ordered]@{
+    GeneratedAtUtc  = [DateTime]::UtcNow.ToString('o')
+    CoveragePercent = [double]$coveragePercent
+    CoverageTarget  = [double]$coveragePercentTarget
+    MissedPaths     = @($missedPaths)
+}
+
+$missedPathReportJsonPath = Join-Path -Path $missedPathReportPath -ChildPath 'CodeCoverage-MissedPaths.json'
+$missedPathReportMarkdownPath = Join-Path -Path $missedPathReportPath -ChildPath 'CodeCoverage-MissedPaths.md'
+$missedPathReport | ConvertTo-Json -Depth 10 | Set-Content -Path $missedPathReportJsonPath -Encoding utf8NoBOM
+
+$missedPathMarkdown = [System.Collections.Generic.List[string]]::new()
+$null = $missedPathMarkdown.Add('# Code Coverage Missed Paths')
+$null = $missedPathMarkdown.Add('')
+$null = $missedPathMarkdown.Add("| Coverage | Target | Missed Paths | Missed Commands |")
+$null = $missedPathMarkdown.Add("| --- | --- | --- | --- |")
+$coverageSummaryRow = '| {0}% | {1}% | {2} | {3} |' -f (
+    [Math]::Round($coveragePercent, 2)
+), (
+    [Math]::Round($coveragePercentTarget, 2)
+), $missedPaths.Count, $codeCoverage.CommandsMissedCount
+$null = $missedPathMarkdown.Add($coverageSummaryRow)
+$null = $missedPathMarkdown.Add('')
+$null = $missedPathMarkdown.Add('## Paths')
+$null = $missedPathMarkdown.Add('| Path | Missed Commands | Missed Lines |')
+$null = $missedPathMarkdown.Add('| --- | ---: | --- |')
+if ($missedPaths.Count -eq 0) {
+    $null = $missedPathMarkdown.Add('| _None_ | 0 |  |')
+} else {
+    foreach ($pathEntry in $missedPaths) {
+        $safePath = ([string]$pathEntry.Path).Replace('|', '\|')
+        $safeLines = ([string]$pathEntry.MissedLines).Replace('|', '\|')
+        $null = $missedPathMarkdown.Add("| $safePath | $($pathEntry.MissedCommands) | $safeLines |")
+    }
+}
+
+$missedPathMarkdown | Set-Content -Path $missedPathReportMarkdownPath -Encoding utf8NoBOM
+Write-Output 'Missed path report generated:'
+$missedPaths | Select-Object -First 20 | Format-Table -Property Path, MissedCommands, MissedLines -AutoSize | Out-String
+if ($env:GITHUB_OUTPUT) {
+    "MissedPathReportPath=$missedPathReportPath" >> $env:GITHUB_OUTPUT
+}
+
 # Build HTML table for 'missed' commands
 $tableheader = @'
 <table>
@@ -300,6 +367,18 @@ LogGroup 'Step Summary - Set step summary' {
                     }
                 }
             }
+
+            Details "Missed paths [$($missedPaths.Count)]" {
+                if ($missedPaths.Count -eq 0) {
+                    Paragraph {
+                        Write-Output 'No missed paths were detected.'
+                    }
+                } else {
+                    Table {
+                        $missedPaths | Select-Object -First 100
+                    }
+                }
+            }
         }
     }
 

.github/workflows/Get-CodeCoverage.yml

@@ -34,3 +34,11 @@ jobs:
           Prerelease: ${{ fromJson(inputs.Settings).Prerelease }}
           Verbose: ${{ fromJson(inputs.Settings).Verbose }}
           Version: ${{ fromJson(inputs.Settings).Version }}
+
+      - name: Upload CodeCoverage-MissedPaths artifact
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: CodeCoverage-MissedPaths
+          path: CodeCoverage-MissedPaths
+          if-no-files-found: warn