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+applyTo: ".github/**/*.{yml,yaml}"
+---
+
+# Publishing Pester Test Results Instructions
+
+This document describes how the PowerShell repository uses GitHub Actions to publish Pester test results.
+
+## Overview
+
+The PowerShell repository uses a custom composite GitHub Action located at `.github/actions/test/process-pester-results` to process and publish Pester test results in CI/CD workflows.
+This action aggregates test results from NUnitXml formatted files, creates a summary in the GitHub Actions job summary, and uploads the results as artifacts.
+
+## How It Works
+
+### Action Location and Structure
+
+**Path**: `.github/actions/test/process-pester-results/`
+
+The action consists of two main files:
+
+1. **action.yml** - The composite action definition
+1. **process-pester-results.ps1** - PowerShell script that processes test results
+
+### Action Inputs
+
+The action accepts the following inputs:
+
+- **name** (required): A descriptive name for the test run (e.g., "UnelevatedPesterTests-CI")
+    - Used for naming the uploaded artifact and in the summary
+    - Format: `junit-pester-{name}`
+
+- **testResultsFolder** (optional): Path to the folder containing test result XML files
+    - Default: `${{ runner.workspace }}/testResults`
+    - The script searches for all `*.xml` files in this folder recursively
+
+### Action Workflow
+
+The action performs the following steps:
+
+1. **Process Test Results**
+    - Runs `process-pester-results.ps1` with the provided name and test results folder
+    - Parses all NUnitXml formatted test result files (`*.xml`)
+    - Aggregates test statistics across all files:
+        - Total test cases
+        - Errors
+        - Failures
+        - Not run tests
+        - Inconclusive tests
+        - Ignored tests
+        - Skipped tests
+        - Invalid tests
+
+1. **Generate Summary**
+    - Creates a markdown summary using the `$GITHUB_STEP_SUMMARY` environment variable
+    - Uses `Write-Log` and `Write-LogGroupStart`/`Write-LogGroupEnd` functions from `build.psm1`
+    - Outputs a formatted summary with all test statistics
+    - Example format:
+
+    ```markdown
+    # Summary of {Name}
+
+    - Total Tests: X
+    - Total Errors: X
+    - Total Failures: X
+    - Total Not Run: X
+    - Total Inconclusive: X
+    - Total Ignored: X
+    - Total Skipped: X
+    - Total Invalid: X
+    ```
+
+1. **Upload Artifacts**
+    - Uses `actions/upload-artifact@v4` to upload test results
+    - Artifact name: `junit-pester-{name}`
+    - Always runs (even if previous steps fail) via `if: always()`
+    - Uploads the entire test results folder
+
+1. **Exit Status**
+    - Fails the job (exit 1) if:
+        - Any test errors occurred (`$testErrorCount -gt 0`)
+        - Any test failures occurred (`$testFailureCount -gt 0`)
+        - No test cases were run (`$testCaseCount -eq 0`)
+
+## Usage in Test Actions
+
+The `process-pester-results` action is called by two platform-specific composite test actions:
+
+### Linux/macOS Tests: `.github/actions/test/nix`
+
+Used in:
+
+- `.github/workflows/linux-ci.yml`
+- `.github/workflows/macos-ci.yml`
+
+Example usage (lines 99-104 in `nix/action.yml`):
+
+```yaml
+- name: Convert, Publish, and Upload Pester Test Results
+  uses: "./.github/actions/test/process-pester-results"
+  with:
+    name: "${{ inputs.purpose }}-${{ inputs.tagSet }}"
+    testResultsFolder: "${{ runner.workspace }}/testResults"
+```
+
+### Windows Tests: `.github/actions/test/windows`
+
+Used in:
+
+- `.github/workflows/windows-ci.yml`
+
+Example usage (line 78-83 in `windows/action.yml`):
+
+```yaml
+- name: Convert, Publish, and Upload Pester Test Results
+  uses: "./.github/actions/test/process-pester-results"
+  with:
+    name: "${{ inputs.purpose }}-${{ inputs.tagSet }}"
+    testResultsFolder: ${{ runner.workspace }}\testResults
+```
+
+## Workflow Integration
+
+The process-pester-results action is integrated into the CI workflows through a multi-level hierarchy:
+
+### Level 1: Main CI Workflows
+
+- `linux-ci.yml`
+- `macos-ci.yml`
+- `windows-ci.yml`
+
+### Level 2: Test Jobs
+
+Each workflow contains multiple test jobs with different purposes and tag sets:
+
+- `UnelevatedPesterTests` with tagSet `CI`
+- `ElevatedPesterTests` with tagSet `CI`
+- `UnelevatedPesterTests` with tagSet `Others`
+- `ElevatedPesterTests` with tagSet `Others`
+
+### Level 3: Platform Test Actions
+
+Test jobs use platform-specific actions:
+
+- `nix` for Linux and macOS
+- `windows` for Windows
+
+### Level 4: Process Results Action
+
+Platform actions call `process-pester-results` to publish results
+
+## Test Execution Flow
+
+1. **Build Phase**: Source code is built (e.g., in `ci_build` job)
+1. **Test Preparation**:
+    - Build artifacts are downloaded
+    - PowerShell is bootstrapped
+    - Test binaries are extracted
+1. **Test Execution**:
+    - `Invoke-CITest` is called with:
+        - `-Purpose`: Test purpose (e.g., "UnelevatedPesterTests")
+        - `-TagSet`: Test category (e.g., "CI", "Others")
+        - `-OutputFormat NUnitXml`: Results format
+    - Results are written to `${{ runner.workspace }}/testResults`
+1. **Results Processing**:
+    - `process-pester-results` action runs
+    - Results are aggregated and summarized
+    - Artifacts are uploaded
+    - Job fails if any tests failed or errored
+
+## Key Dependencies
+
+### PowerShell Modules
+
+- **build.psm1**: Provides utility functions
+    - `Write-Log`: Logging function with GitHub Actions support
+    - `Write-LogGroupStart`: Creates collapsible log groups
+    - `Write-LogGroupEnd`: Closes collapsible log groups
+
+### GitHub Actions Features
+
+- **GITHUB_STEP_SUMMARY**: Environment variable for job summary
+- **actions/upload-artifact@v4**: For uploading test results
+- **Composite Actions**: For reusable workflow steps
+
+### Test Result Format
+
+- **NUnitXml**: XML format for test results
+- Expected XML structure with `test-results` root element containing:
+    - `total`: Total number of tests
+    - `errors`: Number of errors
+    - `failures`: Number of failures
+    - `not-run`: Number of tests not run
+    - `inconclusive`: Number of inconclusive tests
+    - `ignored`: Number of ignored tests
+    - `skipped`: Number of skipped tests
+    - `invalid`: Number of invalid tests
+
+## Best Practices
+
+1. **Naming Convention**: Use descriptive names that include both purpose and tagSet:
+    - Format: `{purpose}-{tagSet}`
+    - Example: `UnelevatedPesterTests-CI`
+
+1. **Test Results Location**:
+    - Default location: `${{ runner.workspace }}/testResults`
+    - Use platform-appropriate path separators (Windows: `\`, Unix: `/`)
+
+1. **Always Upload**: The artifact upload step uses `if: always()` to ensure results are uploaded even when tests fail
+
+1. **Error Handling**: The action will fail the job if:
+    - Tests have errors or failures (intentional fail-fast behavior)
+    - No tests were executed (potential configuration issue)
+    - `GITHUB_STEP_SUMMARY` is not set (environment issue)
+
+## Customizing for Your Repository
+
+To use this pattern in another repository:
+
+1. **Copy the Action Files**:
+    - Copy `.github/actions/test/process-pester-results/` directory
+    - Ensure the PowerShell script has proper permissions
+
+1. **Adjust Dependencies**:
+    - Modify or remove the `Import-Module "$PSScriptRoot/../../../../build.psm1"` line
+    - Implement equivalent `Write-Log` and `Write-LogGroup*` functions if needed
+
+1. **Customize Summary Format**:
+    - Modify the here-string in `process-pester-results.ps1` to change summary format
+    - Add additional metrics or formatting as needed
+
+1. **Call from Your Workflows**:
+
+    ```yaml
+    - name: Process Test Results
+      uses: "./.github/actions/test/process-pester-results"
+      with:
+        name: "my-test-run"
+        testResultsFolder: "path/to/results"
+    ```
+
+## Related Documentation
+
+- [GitHub Actions: Creating composite actions](https://docs.github.com/en/actions/creating-actions/creating-a-composite-action)
+- [GitHub Actions: Job summaries](https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#adding-a-job-summary)
+- [GitHub Actions: Uploading artifacts](https://docs.github.com/en/actions/using-workflows/storing-workflow-data-as-artifacts)
+- [Pester: PowerShell testing framework](https://pester.dev/)
+- [NUnit XML Format](https://docs.nunit.org/articles/nunit/technical-notes/usage/Test-Result-XML-Format.html)
+
+## Troubleshooting
+
+### No Test Results Found
+
+- Verify `testResultsFolder` path is correct
+- Ensure tests are generating NUnitXml formatted output
+- Check that `*.xml` files exist in the specified folder
+
+### Action Fails with "GITHUB_STEP_SUMMARY is not set"
+
+- Ensure the action runs within a GitHub Actions environment
+- Cannot be run locally without mocking this environment variable
+
+### All Tests Pass but Job Fails
+
+- Check if any tests are marked as errors (different from failures)
+- Verify that at least some tests executed (`$testCaseCount -eq 0`)
+
+### Artifact Upload Fails
+
+- Check artifact name for invalid characters
+- Ensure the test results folder exists
+- Verify actions/upload-artifact version compatibility