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[release/v7.6] Fix merge conflict checker for empty file lists and filter *.cs files #26556

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Merged
daxian-dbw merged 1 commit into from
Dec 2, 2025
Merged

[release/v7.6] Fix merge conflict checker for empty file lists and filter *.cs files #26556

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86 changes: 86 additions & 0 deletions .github/actions/infrastructure/merge-conflict-checker/README.md
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# Merge Conflict Checker

This composite GitHub Action checks for Git merge conflict markers in files changed in pull requests.

## Purpose

Automatically detects leftover merge conflict markers (`<<<<<<<`, `=======`, `>>>>>>>`) in pull request files to prevent them from being merged into the codebase.

## Usage

### In a Workflow

```yaml
- name: Check for merge conflict markers
uses: "./.github/actions/infrastructure/merge-conflict-checker"
```

### Complete Example

```yaml
jobs:
merge_conflict_check:
name: Check for Merge Conflict Markers
runs-on: ubuntu-latest
if: github.event_name == 'pull_request'
permissions:
pull-requests: read
contents: read
steps:
- name: checkout
uses: actions/checkout@v5

- name: Check for merge conflict markers
uses: "./.github/actions/infrastructure/merge-conflict-checker"
```

## How It Works

1. **File Detection**: Uses GitHub's API to get the list of files changed in the pull request
2. **Marker Scanning**: Reads each changed file and searches for the following markers:
- `<<<<<<<` (conflict start marker)
- `=======` (conflict separator)
- `>>>>>>>` (conflict end marker)
3. **Result Reporting**:
- If markers are found, the action fails and lists all affected files
- If no markers are found, the action succeeds

## Outputs

- `files-checked`: Number of files that were checked
- `conflicts-found`: Number of files containing merge conflict markers

## Behavior

- **Event Support**: Only works with `pull_request` events
- **File Handling**:
- Checks only files that were added, modified, or renamed
- Skips deleted files
- **Filters out `*.cs` files** (C# files are excluded from merge conflict checking)
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Copilot AI Dec 2, 2025

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The README doesn't explain why *.cs files are excluded from merge conflict checking. Based on the PR description mentioning "exclude *.cs files from merge conflict checking to avoid false positives during C# builds", this rationale should be documented.

Suggestion:

  - **Filters out `*.cs` files** (C# files are excluded from merge conflict checking to avoid false positives from C# build-generated files)

This helps users understand the reasoning behind this design decision.

Suggested change
- **Filters out `*.cs` files** (C# files are excluded from merge conflict checking)
- **Filters out `*.cs` files** (C# files are excluded from merge conflict checking to avoid false positives from C# build-generated files, which may contain patterns resembling merge conflict markers)

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- Skips binary/unreadable files
- Skips directories
- **Empty File List**: Gracefully handles cases where no files need checking (e.g., PRs that only delete files)

## Example Output

When conflict markers are detected:

```
❌ Merge conflict markers detected in the following files:
- src/example.cs
Markers found: <<<<<<<, =======, >>>>>>>
- README.md
Markers found: <<<<<<<, =======, >>>>>>>
Comment on lines +70 to +73
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The example output shows src/example.cs with conflict markers, but this contradicts the documented behavior that *.cs files are filtered out. Since C# files are excluded from merge conflict checking (as stated in line 59), they should not appear in the example output.

Update the example to show only non-cs files, for instance:

❌ Merge conflict markers detected in the following files:
  - README.md
    Markers found: <<<<<<<, =======, >>>>>>>
  - src/example.txt
    Markers found: <<<<<<<, =======, >>>>>>>
Suggested change
- src/example.cs
Markers found: <<<<<<<, =======, >>>>>>>
- README.md
Markers found: <<<<<<<, =======, >>>>>>>
- README.md
Markers found: <<<<<<<, =======, >>>>>>>
- src/example.txt
Markers found: <<<<<<<, =======, >>>>>>>

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Please resolve these conflicts before merging.
```

When no markers are found:

```
✅ No merge conflict markers found
```

## Integration

This action is integrated into the `linux-ci.yml` workflow and runs automatically on all pull requests to ensure code quality before merging.
37 changes: 37 additions & 0 deletions .github/actions/infrastructure/merge-conflict-checker/action.yml
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name: 'Check for Merge Conflict Markers'
description: 'Checks for Git merge conflict markers in changed files for pull requests'
author: 'PowerShell Team'

outputs:
files-checked:
description: 'Number of files checked for merge conflict markers'
value: ${{ steps.check.outputs.files-checked }}
conflicts-found:
description: 'Number of files with merge conflict markers'
value: ${{ steps.check.outputs.conflicts-found }}

runs:
using: 'composite'
steps:
- name: Get changed files
id: changed-files
uses: "./.github/actions/infrastructure/get-changed-files"

- name: Check for merge conflict markers
id: check
shell: pwsh
env:
CHANGED_FILES_JSON: ${{ steps.changed-files.outputs.files }}
run: |
# Get changed files from environment variable (secure against injection)
$changedFilesJson = $env:CHANGED_FILES_JSON
# Ensure we always have an array (ConvertFrom-Json returns null for empty JSON arrays)
$changedFiles = @($changedFilesJson | ConvertFrom-Json)
# Import ci.psm1 and run the check
Import-Module "$env:GITHUB_WORKSPACE/tools/ci.psm1" -Force
Test-MergeConflictMarker -File $changedFiles -WorkspacePath $env:GITHUB_WORKSPACE
branding:
icon: 'alert-triangle'
color: 'red'
246 changes: 246 additions & 0 deletions test/infrastructure/ciModule.Tests.ps1
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# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.

# NOTE: This test file tests the Test-MergeConflictMarker function which detects Git merge conflict markers.
# IMPORTANT: Do NOT use here-strings or literal conflict markers (e.g., "<<<<<<<", "=======", ">>>>>>>")
# in this file, as they will trigger conflict marker detection in CI pipelines.
# Instead, use string multiplication (e.g., '<' * 7) to dynamically generate these markers at runtime.

Describe "Test-MergeConflictMarker" {
BeforeAll {
# Import the module
Import-Module "$PSScriptRoot/../../tools/ci.psm1" -Force

# Create a temporary test workspace
$script:testWorkspace = Join-Path $TestDrive "workspace"
New-Item -ItemType Directory -Path $script:testWorkspace -Force | Out-Null

# Create temporary output files
$script:testOutputPath = Join-Path $TestDrive "outputs.txt"
$script:testSummaryPath = Join-Path $TestDrive "summary.md"
}

AfterEach {
# Clean up test files after each test
if (Test-Path $script:testWorkspace) {
Get-ChildItem $script:testWorkspace -File -ErrorAction SilentlyContinue | Remove-Item -Force -ErrorAction SilentlyContinue
}
Remove-Item $script:testOutputPath -Force -ErrorAction SilentlyContinue
Remove-Item $script:testSummaryPath -Force -ErrorAction SilentlyContinue
}

Context "When no files are provided" {
It "Should handle empty file array gracefully" {
# The function now accepts empty arrays to handle cases like delete-only PRs
$emptyArray = @()
Test-MergeConflictMarker -File $emptyArray -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "files-checked=0"
$outputs | Should -Contain "conflicts-found=0"

$summary = Get-Content $script:testSummaryPath -Raw
$summary | Should -Match "No Files to Check"
}
}

Context "When files have no conflicts" {
It "Should pass for clean files" {
$testFile = Join-Path $script:testWorkspace "clean.txt"
"This is a clean file" | Out-File $testFile -Encoding utf8

Test-MergeConflictMarker -File @("clean.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "files-checked=1"
$outputs | Should -Contain "conflicts-found=0"

$summary = Get-Content $script:testSummaryPath -Raw
$summary | Should -Match "No Conflicts Found"
}
}

Context "When files have conflict markers" {
It "Should detect <<<<<<< marker" {
$testFile = Join-Path $script:testWorkspace "conflict1.txt"
"Some content`n" + ('<' * 7) + " HEAD`nConflicting content" | Out-File $testFile -Encoding utf8

{ Test-MergeConflictMarker -File @("conflict1.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath } | Should -Throw

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "files-checked=1"
$outputs | Should -Contain "conflicts-found=1"
}

It "Should detect ======= marker" {
$testFile = Join-Path $script:testWorkspace "conflict2.txt"
"Some content`n" + ('=' * 7) + "`nMore content" | Out-File $testFile -Encoding utf8

{ Test-MergeConflictMarker -File @("conflict2.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath } | Should -Throw
}

It "Should detect >>>>>>> marker" {
$testFile = Join-Path $script:testWorkspace "conflict3.txt"
"Some content`n" + ('>' * 7) + " branch-name`nMore content" | Out-File $testFile -Encoding utf8

{ Test-MergeConflictMarker -File @("conflict3.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath } | Should -Throw
}

It "Should detect multiple markers in one file" {
$testFile = Join-Path $script:testWorkspace "conflict4.txt"
$content = "Some content`n" + ('<' * 7) + " HEAD`nContent A`n" + ('=' * 7) + "`nContent B`n" + ('>' * 7) + " branch`nMore content"
$content | Out-File $testFile -Encoding utf8

{ Test-MergeConflictMarker -File @("conflict4.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath } | Should -Throw

$summary = Get-Content $script:testSummaryPath -Raw
$summary | Should -Match "Conflicts Detected"
$summary | Should -Match "conflict4.txt"
}

It "Should detect conflicts in multiple files" {
$testFile1 = Join-Path $script:testWorkspace "conflict5.txt"
('<' * 7) + " HEAD" | Out-File $testFile1 -Encoding utf8

$testFile2 = Join-Path $script:testWorkspace "conflict6.txt"
('=' * 7) | Out-File $testFile2 -Encoding utf8

{ Test-MergeConflictMarker -File @("conflict5.txt", "conflict6.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath } | Should -Throw

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "files-checked=2"
$outputs | Should -Contain "conflicts-found=2"
}
}

Context "When markers are not at line start" {
It "Should not detect markers in middle of line" {
$testFile = Join-Path $script:testWorkspace "notconflict.txt"
"This line has <<<<<<< in the middle" | Out-File $testFile -Encoding utf8

Test-MergeConflictMarker -File @("notconflict.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "conflicts-found=0"
}

It "Should not detect markers with wrong number of characters" {
$testFile = Join-Path $script:testWorkspace "wrongcount.txt"
('<' * 6) + " Only 6`n" + ('<' * 8) + " 8 characters" | Out-File $testFile -Encoding utf8

Test-MergeConflictMarker -File @("wrongcount.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "conflicts-found=0"
}
}

Context "When handling special file scenarios" {
It "Should skip non-existent files" {
Test-MergeConflictMarker -File @("nonexistent.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "files-checked=0"
}

It "Should handle absolute paths" {
$testFile = Join-Path $script:testWorkspace "absolute.txt"
"Clean content" | Out-File $testFile -Encoding utf8

Test-MergeConflictMarker -File @($testFile) -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "conflicts-found=0"
}

It "Should handle mixed relative and absolute paths" {
$testFile1 = Join-Path $script:testWorkspace "relative.txt"
"Clean" | Out-File $testFile1 -Encoding utf8

$testFile2 = Join-Path $script:testWorkspace "absolute.txt"
"Clean" | Out-File $testFile2 -Encoding utf8

Test-MergeConflictMarker -File @("relative.txt", $testFile2) -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Should -Contain "files-checked=2"
$outputs | Should -Contain "conflicts-found=0"
}
}
Comment on lines +138 to +169
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Missing test coverage for the *.cs file filtering feature. The PR description and implementation include logic to filter out *.cs files from merge conflict checking (lines 1057-1069 in ci.psm1), but there are no tests validating this behavior.

Suggested tests to add:

  1. Test that *.cs files are filtered out when provided
  2. Test that the filtered count is correctly reported
  3. Test that when all files are *.cs, the function handles it gracefully (already implemented in code but not tested)
  4. Test mixed scenarios with both *.cs and non-cs files

Example test:

It "Should filter out *.cs files from checking" {
    $testCsFile = Join-Path $script:testWorkspace "file.cs"
    $testTxtFile = Join-Path $script:testWorkspace "file.txt"
    "Clean content" | Out-File $testCsFile -Encoding utf8
    "Clean content" | Out-File $testTxtFile -Encoding utf8

    Test-MergeConflictMarker -File @("file.cs", "file.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

    $outputs = Get-Content $script:testOutputPath
    $outputs | Should -Contain "files-checked=1"  # Only txt file checked
}

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Context "When summary and output generation" {
It "Should generate proper GitHub Actions outputs format" {
$testFile = Join-Path $script:testWorkspace "test.txt"
"Clean file" | Out-File $testFile -Encoding utf8

Test-MergeConflictMarker -File @("test.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath

$outputs = Get-Content $script:testOutputPath
$outputs | Where-Object {$_ -match "^files-checked=\d+$"} | Should -Not -BeNullOrEmpty
$outputs | Where-Object {$_ -match "^conflicts-found=\d+$"} | Should -Not -BeNullOrEmpty
}

It "Should generate markdown summary with conflict details" {
$testFile = Join-Path $script:testWorkspace "marked.txt"
$content = "Line 1`n" + ('<' * 7) + " HEAD`nLine 3`n" + ('=' * 7) + "`nLine 5"
$content | Out-File $testFile -Encoding utf8

{ Test-MergeConflictMarker -File @("marked.txt") -WorkspacePath $script:testWorkspace -OutputPath $script:testOutputPath -SummaryPath $script:testSummaryPath } | Should -Throw

$summary = Get-Content $script:testSummaryPath -Raw
$summary | Should -Match "# Merge Conflict Marker Check Results"
$summary | Should -Match "marked.txt"
$summary | Should -Match "\| Line \| Marker \|"
}
}
}

Describe "Install-CIPester" {
BeforeAll {
# Import the module
Import-Module "$PSScriptRoot/../../tools/ci.psm1" -Force
}

Context "When checking function exists" {
It "Should export Install-CIPester function" {
$function = Get-Command Install-CIPester -ErrorAction SilentlyContinue
$function | Should -Not -BeNullOrEmpty
$function.ModuleName | Should -Be 'ci'
}

It "Should have expected parameters" {
$function = Get-Command Install-CIPester
$function.Parameters.Keys | Should -Contain 'MinimumVersion'
$function.Parameters.Keys | Should -Contain 'MaximumVersion'
$function.Parameters.Keys | Should -Contain 'Force'
}

It "Should accept version parameters" {
$function = Get-Command Install-CIPester
$function.Parameters['MinimumVersion'].ParameterType.Name | Should -Be 'String'
$function.Parameters['MaximumVersion'].ParameterType.Name | Should -Be 'String'
$function.Parameters['Force'].ParameterType.Name | Should -Be 'SwitchParameter'
}
}

Context "When validating real execution" {
# These tests only run in CI where we can safely install/test Pester

It "Should successfully run without errors when Pester exists" {
if (!$env:CI) {
Set-ItResult -Skipped -Because "Test requires CI environment to safely install Pester"
}

{ Install-CIPester -ErrorAction Stop } | Should -Not -Throw
}

It "Should accept custom version parameters" {
if (!$env:CI) {
Set-ItResult -Skipped -Because "Test requires CI environment to safely install Pester"
}

{ Install-CIPester -MinimumVersion '4.0.0' -MaximumVersion '5.99.99' -ErrorAction Stop } | Should -Not -Throw
}
}
}

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