<!-- GENERATED FILE - DO NOT EDIT This file was generated by [MarkdownSnippets](https://github.com/SimonCropp/MarkdownSnippets). Source File: /readme.source.md To change this file edit the source file and then run MarkdownSnippets. -->

<img src="/src/icon.png" height="30px"> DiffEngine

DiffEngine manages launching and cleanup of diff tools. It is designed to be used by any Snapshot/Approval testing library.<!-- singleLineInclude: intro. path: /docs/mdsource/intro.include.md -->

See Milestones for release notes.

Currently used by:

• ApprovalTests
• Shouldly
• Verify

Sponsors

Entity Framework Extensions<!-- include: sponsors. path: /docs/mdsource/sponsors.include.md -->

Entity Framework Extensions is a major sponsor and is proud to contribute to the development this project.

Developed using JetBrains IDEs

<!-- endInclude -->

<!-- toc -->

Contents

• NuGet
• Supported Tools
• Launching a tool
• Closing a tool
• File type detection
• BuildServerDetector
  • Override in tests
• AiCliDetector
• Disable for a machine/process
• Disable in code
• Icons<!-- endToc -->
• Tools<!-- include: doc-index. path: /docs/mdsource/doc-index.include.md -->
• Tool Order
• Custom Tool
• DiffEngineTray
• Code versus machine level settings<!-- endInclude -->

NuGet

• https://nuget.org/packages/DiffEngine/

Supported Tools

• AraxisMerge Windows/OSX (Cost: Paid)<!-- include: diffToolList. path: /src/DiffEngine.Tests/diffToolList.include.md -->
• BeyondCompare Windows/OSX/Linux (Cost: Paid)
• Cursor Windows/OSX/Linux (Cost: Free and Paid)
• DeltaWalker Windows/OSX (Cost: Paid)
• Diffinity Windows (Cost: Free with option to donate)
• ExamDiff Windows (Cost: Paid)
• Guiffy Windows/OSX (Cost: Paid)
• Kaleidoscope OSX (Cost: Paid)
• KDiff3 Windows/OSX (Cost: Free)
• Meld Windows/OSX/Linux (Cost: Free)
• MsExcelDiff Windows (Cost: Requires Excel installed)
• MsWordDiff Windows (Cost: Requires Word installed)
• Neovim Windows/OSX/Linux (Cost: Free with option to sponsor)
• P4Merge Windows/OSX/Linux (Cost: Free)
• Rider Windows/OSX/Linux (Cost: Paid with free option for OSS)
• SublimeMerge Windows/OSX/Linux (Cost: Paid)
• TkDiff OSX (Cost: Free)
• TortoiseGitIDiff Windows (Cost: Free)
• TortoiseGitMerge Windows (Cost: Free)
• TortoiseIDiff Windows (Cost: Free)
• TortoiseMerge Windows (Cost: Free)
• Vim Windows/OSX (Cost: Free with option to donate)
• VisualStudio Windows (Cost: Paid and free options)
• VisualStudioCode Windows/OSX/Linux (Cost: Free)
• WinMerge Windows (Cost: Free with option to donate)<!-- endInclude -->

Launching a tool

A tool can be launched using the following:

<!-- snippet: DiffRunnerLaunch -->

<a id='snippet-DiffRunnerLaunch'></a>

await DiffRunner.LaunchAsync(tempFile, targetFile);

^{<a href='/src/DiffEngine.Tests/DiffRunnerTests.cs#L68-L72' title='Snippet source file'>snippet source</a> | <a href='#snippet-DiffRunnerLaunch' title='Start of snippet'>anchor</a>}

<!-- endSnippet -->

Note that this method will respect the above difference behavior in terms of Auto refresh and MDI behaviors.

Closing a tool

A tool can be closed using the following:

<!-- snippet: DiffRunnerKill -->

<a id='snippet-DiffRunnerKill'></a>

DiffRunner.Kill(file1, file2);

^{<a href='/src/DiffEngine.Tests/DiffRunnerTests.cs#L82-L86' title='Snippet source file'>snippet source</a> | <a href='#snippet-DiffRunnerKill' title='Start of snippet'>anchor</a>}

<!-- endSnippet -->

Note that this method will respect the above difference behavior in terms of MDI behavior.

File type detection

DiffEngine use EmptyFiles to determine if a given file or extension is a binary or text. Custom extensions can be added, or existing ones changed.

BuildServerDetector

BuildServerDetector.Detected returns true if the current code is running on a build/CI server.

Supports:

• AppVeyor
• Travis
• Jenkins
• GitHub Actions
• AzureDevops
• TeamCity
• MyGet
• GitLab
• GoCD

There are also individual properties to check for each specific build system

<!-- snippet: BuildServerDetectorProps -->

<a id='snippet-BuildServerDetectorProps'></a>

var isWsl = BuildServerDetector.IsWsl;
var isTravis = BuildServerDetector.IsTravis;
var isJenkins = BuildServerDetector.IsJenkins;
var isGithubAction = BuildServerDetector.IsGithubAction;
var isAzureDevops = BuildServerDetector.IsAzureDevops;
var isTeamCity = BuildServerDetector.IsTeamCity;
var isGitLab = BuildServerDetector.IsGitLab;
var isMyGet = BuildServerDetector.IsMyGet;
var isGoDc = BuildServerDetector.IsGoDc;
var isDocker = BuildServerDetector.IsDocker;
var isAppVeyor = BuildServerDetector.IsAppVeyor;

^{<a href='/src/DiffEngine.Tests/BuildServerDetectorTest.cs#L8-L22' title='Snippet source file'>snippet source</a> | <a href='#snippet-BuildServerDetectorProps' title='Start of snippet'>anchor</a>}

<!-- endSnippet -->

Override in tests

BuildServerDetector.Detected can be set at test time. The value is stored in an AsyncLocal, so it is scoped to the current async context and does not leak to other threads or tests running in parallel.

<!-- snippet: BuildServerDetectorDetectedOverride -->

<a id='snippet-BuildServerDetectorDetectedOverride'></a>

[Test]
public async Task SetDetectedPersistsInAsyncContext()
{
    var original = BuildServerDetector.Detected;
    try
    {
        BuildServerDetector.Detected = true;
        await Assert.That(BuildServerDetector.Detected).IsTrue();

        await Task.Delay(1);

        await Assert.That(BuildServerDetector.Detected).IsTrue();
    }
    finally
    {
        BuildServerDetector.Detected = original;
    }
}

[Test]
public async Task SetDetectedDoesNotLeakToOtherContexts()
{
    var parentValue = BuildServerDetector.Detected;

    await Task.Run(async () =>
    {
        BuildServerDetector.Detected = true;
        await Assert.That(BuildServerDetector.Detected).IsTrue();
    });

    await Assert.That(BuildServerDetector.Detected).IsEqualTo(parentValue);
}

^{<a href='/src/DiffEngine.Tests/BuildServerDetectorTest.cs#L27-L62' title='Snippet source file'>snippet source</a> | <a href='#snippet-BuildServerDetectorDetectedOverride' title='Start of snippet'>anchor</a>}

<!-- endSnippet -->

AiCliDetector

AiCliDetector.Detected returns true if the current code is running in an AI-powered CLI environment.

Supports:

• [GitHub Copilot CLI](https://docs.github.com/en