From e3638e809319f2f68fde2f1ffccf9791d5d6d7e7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Jare=C5=A1?= <me@jakubjares.com>
Date: Fri, 24 Jul 2026 00:04:49 +0200
Subject: [PATCH] Resolve relative CodeCoverage.ReportRoot to an absolute path
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Get-RelativePath makes the coverage report paths relative by stripping the
report root prefix off the (absolute) file paths. When ReportRoot, or its
Run.RepoRoot fallback, is a relative path the prefix never matches, so the
report keeps the absolute paths.

Get-ReportRoot now resolves the path to absolute before it is used.

Fix #2920

🤖
---
 src/functions/Coverage.ps1       | 18 +++++++++++++++---
 tst/functions/Coverage.Tests.ps1 | 26 ++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/functions/Coverage.ps1 b/src/functions/Coverage.ps1
index a65784ee3..03fb25aa6 100644
--- a/src/functions/Coverage.ps1
+++ b/src/functions/Coverage.ps1
@@ -727,11 +727,23 @@ function Get-CoverageReport {
 }
 
 function Get-ReportRoot {
-    if ($null -ne $PesterPreference.CodeCoverage.ReportRoot.Value) {
-        return $PesterPreference.CodeCoverage.ReportRoot.Value
+    $reportRoot = if ($null -ne $PesterPreference.CodeCoverage.ReportRoot.Value) {
+        $PesterPreference.CodeCoverage.ReportRoot.Value
+    }
+    else {
+        $PesterPreference.Run.RepoRoot.Value
+    }
+
+    if ([string]::IsNullOrEmpty($reportRoot)) {
+        return $reportRoot
     }
 
-    $PesterPreference.Run.RepoRoot.Value
+    # Resolve to an absolute path. Get-RelativePath strips this prefix off the
+    # (absolute) file paths, so a relative ReportRoot/RepoRoot would never match
+    # and the report would keep the absolute paths instead of making them
+    # relative (#2920). GetUnresolvedProviderPathFromPSPath resolves against the
+    # current location without requiring the path to exist.
+    $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath($reportRoot)
 }
 
 function Get-RelativePath {
diff --git a/tst/functions/Coverage.Tests.ps1 b/tst/functions/Coverage.Tests.ps1
index 29f23db4f..dda93ff78 100644
--- a/tst/functions/Coverage.Tests.ps1
+++ b/tst/functions/Coverage.Tests.ps1
@@ -1414,4 +1414,30 @@ InPesterModuleScope {
     #             }
     #         }
     #     }
+
+    Describe 'Get-ReportRoot' {
+        It 'resolves a relative CodeCoverage.ReportRoot to an absolute path (#2920)' {
+            $PesterPreference = [PesterConfiguration]::Default
+            $PesterPreference.CodeCoverage.ReportRoot = '.'
+            [System.IO.Path]::IsPathRooted((Get-ReportRoot)) | Should -BeTrue
+        }
+
+        It 'resolves a relative Run.RepoRoot fallback to an absolute path (#2920)' {
+            $PesterPreference = [PesterConfiguration]::Default
+            $PesterPreference.Run.RepoRoot = '.'
+            [System.IO.Path]::IsPathRooted((Get-ReportRoot)) | Should -BeTrue
+        }
+
+        It 'lets a relative ReportRoot still yield relative file paths in the report (#2920)' {
+            # Reproduces #2920: with a relative ReportRoot, Get-RelativePath could
+            # not strip the prefix from the absolute file paths, so the report kept
+            # the absolute paths. Get-ReportRoot now resolves to absolute first.
+            $PesterPreference = [PesterConfiguration]::Default
+            $PesterPreference.CodeCoverage.ReportRoot = '.'
+            $absRoot = $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath('.')
+            $absFile = Join-Path -Path $absRoot -ChildPath (Join-Path 'sub' 'File.ps1')
+            $expected = 'sub{0}File.ps1' -f [System.IO.Path]::DirectorySeparatorChar
+            Get-RelativePath -Path $absFile -RelativeTo (Get-ReportRoot) | Should -Be $expected
+        }
+    }
 }