Fix CI coverage aggregation by normalizing LCOV source paths

.github/workflows/rust.yml

@@ -112,8 +112,9 @@ jobs:
         if: always()
         run: |-
           Import-Module ./helpers.build.psm1 -Force
+          $binPath = Get-ArtifactDirectoryPath | Select-Object -ExpandProperty Bin
           $exportParams = @{
-            BinDirectory     = Join-Path $PWD 'bin'
+            BinDirectory     = $binPath
             ProfileDirectory = '${{ steps.coverage-env.outputs.prof_dir }}'
             OutputPath       = 'pester-lcov.info'
             Verbose          = $true
@@ -203,8 +204,9 @@ jobs:
         if: always()
         run: |-
           Import-Module ./helpers.build.psm1 -Force
+          $binPath = Get-ArtifactDirectoryPath | Select-Object -ExpandProperty Bin
           $exportParams = @{
-            BinDirectory     = Join-Path $PWD 'bin'
+            BinDirectory     = $binPath
             ProfileDirectory = '${{ steps.coverage-env.outputs.prof_dir }}'
             OutputPath       = 'pester-lcov.info'
             Verbose          = $true
@@ -301,8 +303,9 @@ jobs:
         if: always()
         run: |-
           Import-Module ./helpers.build.psm1 -Force
+          $binPath = Get-ArtifactDirectoryPath | Select-Object -ExpandProperty Bin
           $exportParams = @{
-            BinDirectory     = Join-Path $PWD 'bin'
+            BinDirectory     = $binPath
             ProfileDirectory = '${{ steps.coverage-env.outputs.prof_dir }}'
             OutputPath       = 'pester-lcov.info'
             Verbose          = $true
@@ -326,7 +329,11 @@ jobs:
 
   coverage-report:
     if: github.event_name == 'pull_request'
-    needs: [linux-build, macos-build, windows-build, linux-pester, macos-pester, windows-pester]
+    # Use Linux coverage only: merging all platforms inflates total line count
+    # because each platform has platform-specific source files (Windows adds ~4500
+    # lines from registry/service/DISM resources). Single-platform coverage matches
+    # local `build.ps1 -codecoverage` results and avoids misleadingly low percentages.
+    needs: [linux-build, linux-pester]
     runs-on: ubuntu-latest
     permissions:
       pull-requests: write
@@ -339,7 +346,7 @@ jobs:
       - name: Download coverage artifacts
         uses: actions/download-artifact@v4
         with:
-          pattern: '*-coverage'
+          pattern: 'linux*coverage'
           path: coverage-data
 
       - name: Consolidate coverage data

helpers.build.psm1

@@ -2099,15 +2099,19 @@ function Export-PesterCodeCoverageReport {
             throw "llvm-profdata merge failed with exit code $LASTEXITCODE"
         }
 
-        # Find all executable binaries in the bin directory
-        $nonBinaryExtensions = @('.pdb', '.d', '.ps1', '.psm1', '.psd1', '.json', '.yaml', '.yml', '.txt', '.md')
+        # Find all executable binaries in the bin directory.
+        # On Unix, Rust produces binaries with no file extension. We identify them by
+        # excluding known non-binary extensions. We cannot rely solely on the execute
+        # permission bit because artifact upload/download may not preserve it.
+        $nonBinaryExtensions = @('.pdb', '.d', '.ps1', '.psm1', '.psd1', '.json', '.yaml', '.yml', '.txt', '.md', '.sh')
         $binaries = @(
             if ($IsWindows) {
                 Get-ChildItem -Path $BinDirectory -Filter '*.exe' -File
             } else {
                 Get-ChildItem -Path $BinDirectory -File | Where-Object {
-                    $_.Extension -notin $nonBinaryExtensions -and
-                    ($_.Mode -match 'x')
+                    -not $_.Extension -or
+                    ($_.Extension -notin $nonBinaryExtensions -and
+                     $_.UnixMode -and $_.UnixMode -match 'x')
                 }
             }
         )
@@ -2147,6 +2151,76 @@ function Export-PesterCodeCoverageReport {
     }
 }
 
+function ConvertTo-NormalizedLcovSourcePath {
+    <#
+        .SYNOPSIS
+        Normalizes an LCOV SF: path to a relative, forward-slash path for consistent merging.
+
+        .DESCRIPTION
+        LCOV files generated on different platforms contain platform-specific absolute paths
+        (e.g., /home/runner/work/DSC/DSC/src/foo.rs on Linux, D:\a\DSC\DSC\src\foo.rs on
+        Windows). This function strips common CI workspace prefixes and normalizes path
+        separators so that the same source file is recognized across platforms when merging
+        coverage data.
+
+        .PARAMETER RawPath
+        The raw SF: path value from an LCOV file.
+
+        .OUTPUTS
+        A normalized relative path using forward slashes.
+    #>
+    [CmdletBinding()]
+    [OutputType([string])]
+    param(
+        [Parameter(Mandatory)]
+        [string]$RawPath
+    )
+
+    process {
+        $normalized = $RawPath
+
+        # Normalize backslashes to forward slashes
+        $normalized = $normalized.Replace('\', '/')
+
+        # Strip common CI workspace prefixes:
+        # GitHub Actions Linux/macOS: /home/runner/work/<repo>/<repo>/ or /Users/runner/work/<repo>/<repo>/
+        # GitHub Actions Windows: D:/a/<repo>/<repo>/ (after backslash normalization)
+        $patterns = @(
+            '^/home/[^/]+/work/[^/]+/[^/]+/'     # Linux: /home/runner/work/DSC/DSC/
+            '^/Users/[^/]+/work/[^/]+/[^/]+/'     # macOS: /Users/runner/work/DSC/DSC/
+            '^[A-Za-z]:/a/[^/]+/[^/]+/'           # Windows: D:/a/DSC/DSC/
+        )
+
+        foreach ($pattern in $patterns) {
+            if ($normalized -match $pattern) {
+                $normalized = $normalized -replace $pattern, ''
+                break
+            }
+        }
+
+        # If still absolute (starts with / or a drive letter), try to find a known source
+        # directory marker and make relative from there (e.g., from the crate root)
+        if ($normalized.StartsWith('/') -or $normalized -match '^[A-Za-z]:/') {
+            # Look for common Rust project markers in the path
+            $markers = @('/src/', '/tests/', '/benches/', '/examples/')
+            foreach ($marker in $markers) {
+                $markerIdx = $normalized.IndexOf($marker)
+                if ($markerIdx -gt 0) {
+                    # Find the crate directory (one level up from src/tests/etc.)
+                    $prefix = $normalized.Substring(0, $markerIdx)
+                    $lastSlash = $prefix.LastIndexOf('/')
+                    if ($lastSlash -ge 0) {
+                        $normalized = $normalized.Substring($lastSlash + 1)
+                        break
+                    }
+                }
+            }
+        }
+
+        return $normalized
+    }
+}
+
 function Merge-LcovFile {
     <#
         .SYNOPSIS
@@ -2157,6 +2231,10 @@ function Merge-LcovFile {
         counts for matching source files. When the same line appears in multiple reports,
         the hit counts are summed.
 
+        Source file paths are normalized to relative paths before merging so that LCOV
+        files generated on different platforms (with different absolute workspace paths
+        and path separators) are correctly recognized as covering the same source files.
+
         .PARAMETER Path
         Array of paths to LCOV files to merge.
 
@@ -2173,7 +2251,7 @@ function Merge-LcovFile {
     )
 
     process {
-        # Structure: $coverage[sourceFile][lineNumber] = hitCount
+        # Structure: $coverage[normalizedSourceFile][lineNumber] = hitCount
         $coverage = @{}
 
         foreach ($lcovPath in $Path) {
@@ -2185,7 +2263,7 @@ function Merge-LcovFile {
             $currentFile = $null
             foreach ($line in Get-Content -Path $lcovPath) {
                 if ($line -match '^SF:(.+)$') {
-                    $currentFile = $Matches[1]
+                    $currentFile = ConvertTo-NormalizedLcovSourcePath -RawPath $Matches[1]
                     if (-not $coverage.ContainsKey($currentFile)) {
                         $coverage[$currentFile] = @{}
                     }

tests/helpers.build.coverage.tests.ps1

@@ -0,0 +1,170 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+Describe 'ConvertTo-NormalizedLcovSourcePath' {
+    BeforeAll {
+        Import-Module (Join-Path $PSScriptRoot '..' 'helpers.build.psm1') -Force
+    }
+
+    Context 'Linux GitHub Actions paths' {
+        It 'Strips /home/runner/work/<repo>/<repo>/ prefix' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath '/home/runner/work/DSC/DSC/dsc_lib/src/dscresources/command_resource.rs'
+            $result | Should -Be 'dsc_lib/src/dscresources/command_resource.rs'
+        }
+
+        It 'Handles varying usernames' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath '/home/vsts/work/MyProject/MyProject/src/main.rs'
+            $result | Should -Be 'src/main.rs'
+        }
+    }
+
+    Context 'macOS GitHub Actions paths' {
+        It 'Strips /Users/runner/work/<repo>/<repo>/ prefix' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath '/Users/runner/work/DSC/DSC/dsc_lib/src/dscresources/command_resource.rs'
+            $result | Should -Be 'dsc_lib/src/dscresources/command_resource.rs'
+        }
+    }
+
+    Context 'Windows GitHub Actions paths' {
+        It 'Strips D:/a/<repo>/<repo>/ prefix after backslash normalization' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath 'D:\a\DSC\DSC\dsc_lib\src\dscresources\command_resource.rs'
+            $result | Should -Be 'dsc_lib/src/dscresources/command_resource.rs'
+        }
+
+        It 'Handles C: drive' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath 'C:\a\DSC\DSC\dsc_lib\src\main.rs'
+            $result | Should -Be 'dsc_lib/src/main.rs'
+        }
+    }
+
+    Context 'Already relative paths' {
+        It 'Returns relative paths unchanged (with normalized separators)' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath 'dsc_lib/src/main.rs'
+            $result | Should -Be 'dsc_lib/src/main.rs'
+        }
+
+        It 'Normalizes backslashes in relative paths' {
+            $result = ConvertTo-NormalizedLcovSourcePath -RawPath 'dsc_lib\src\main.rs'
+            $result | Should -Be 'dsc_lib/src/main.rs'
+        }
+    }
+
+    Context 'Cross-platform consistency' {
+        It 'Produces the same output for the same file on all platforms' {
+            $linuxPath = '/home/runner/work/DSC/DSC/dsc_lib/src/configure.rs'
+            $macosPath = '/Users/runner/work/DSC/DSC/dsc_lib/src/configure.rs'
+            $windowsPath = 'D:\a\DSC\DSC\dsc_lib\src\configure.rs'
+
+            $linuxResult = ConvertTo-NormalizedLcovSourcePath -RawPath $linuxPath
+            $macosResult = ConvertTo-NormalizedLcovSourcePath -RawPath $macosPath
+            $windowsResult = ConvertTo-NormalizedLcovSourcePath -RawPath $windowsPath
+
+            $linuxResult | Should -Be $macosResult
+            $macosResult | Should -Be $windowsResult
+            $linuxResult | Should -Be 'dsc_lib/src/configure.rs'
+        }
+    }
+}
+
+Describe 'Merge-LcovFile' {
+    BeforeAll {
+        Import-Module (Join-Path $PSScriptRoot '..' 'helpers.build.psm1') -Force
+    }
+
+    Context 'Merging files with different platform paths for the same source' {
+        BeforeAll {
+            $linuxLcov = Join-Path $TestDrive 'linux-lcov.info'
+            $macosLcov = Join-Path $TestDrive 'macos-lcov.info'
+            $windowsLcov = Join-Path $TestDrive 'windows-lcov.info'
+            $outputPath = Join-Path $TestDrive 'merged.info'
+
+            # Same file, same line coverage, different absolute paths
+            @'
+SF:/home/runner/work/DSC/DSC/dsc_lib/src/main.rs
+DA:1,5
+DA:2,3
+DA:3,0
+LF:3
+LH:2
+end_of_record
+'@ | Set-Content -Path $linuxLcov -NoNewline
+
+            @'
+SF:/Users/runner/work/DSC/DSC/dsc_lib/src/main.rs
+DA:1,2
+DA:2,0
+DA:3,4
+LF:3
+LH:2
+end_of_record
+'@ | Set-Content -Path $macosLcov -NoNewline
+
+            @'
+SF:D:\a\DSC\DSC\dsc_lib\src\main.rs
+DA:1,1
+DA:2,0
+DA:3,0
+LF:3
+LH:1
+end_of_record
+'@ | Set-Content -Path $windowsLcov -NoNewline
+
+            Merge-LcovFile -Path @($linuxLcov, $macosLcov, $windowsLcov) -OutputPath $outputPath
+            $script:mergedContent = Get-Content -Path $outputPath -Raw
+        }
+
+        It 'Produces a single source file entry (not three duplicates)' {
+            $sfCount = ([regex]::Matches($script:mergedContent, '^SF:', [System.Text.RegularExpressions.RegexOptions]::Multiline)).Count
+            $sfCount | Should -Be 1
+        }
+
+        It 'Sums hit counts for matching lines' {
+            # Line 1: 5 + 2 + 1 = 8
+            $script:mergedContent | Should -Match '(?m)^DA:1,8\r?$'
+            # Line 2: 3 + 0 + 0 = 3
+            $script:mergedContent | Should -Match '(?m)^DA:2,3\r?$'
+            # Line 3: 0 + 4 + 0 = 4
+            $script:mergedContent | Should -Match '(?m)^DA:3,4\r?$'
+        }
+
+        It 'Reports all 3 lines covered (all have non-zero sum)' {
+            $script:mergedContent | Should -Match '(?m)^LH:3\r?$'
+        }
+
+        It 'Reports 3 total lines' {
+            $script:mergedContent | Should -Match '(?m)^LF:3\r?$'
+        }
+    }
+
+    Context 'Merging files with unique sources that do not overlap' {
+        BeforeAll {
+            $lcov1 = Join-Path $TestDrive 'lcov1.info'
+            $lcov2 = Join-Path $TestDrive 'lcov2.info'
+            $outputPath = Join-Path $TestDrive 'merged-unique.info'
+
+            @'
+SF:/home/runner/work/DSC/DSC/dsc_lib/src/foo.rs
+DA:1,5
+LF:1
+LH:1
+end_of_record
+'@ | Set-Content -Path $lcov1 -NoNewline
+
+            @'
+SF:/home/runner/work/DSC/DSC/dsc_lib/src/bar.rs
+DA:1,3
+LF:1
+LH:1
+end_of_record
+'@ | Set-Content -Path $lcov2 -NoNewline
+
+            Merge-LcovFile -Path @($lcov1, $lcov2) -OutputPath $outputPath
+            $script:mergedUniqueContent = Get-Content -Path $outputPath -Raw
+        }
+
+        It 'Preserves both source file entries' {
+            $sfCount = ([regex]::Matches($script:mergedUniqueContent, '^SF:', [System.Text.RegularExpressions.RegexOptions]::Multiline)).Count
+            $sfCount | Should -Be 2
+        }
+    }
+}