Assent is a simple assertion library for long strings. By default it uses common diff tools to report on and resolve test failures.

It is test framework agnostic and works with .NET Framework 4.5, NET Standard 1.3 and .NET Core 1.0.

Install the package from nuget by adding Assent to your project.json dependencies or running install-package Assent from the NuGet tool window.

In your test, do your usual setup and execution, but replace your assert line with:

this.Assent("String To Assert")

The behaviour can be customised by passing a Configuration object:

var configuration = configuration.UsingExtension("json");
this.Assent("String To Assert", configuration);

You can use your favourite assertion library, see the Comparer wiki page.

When the test is run, it will look for an approved file in the same directory as the code file. See Naming on how this is achieved and how to customise this. On the first run, an empty approved file is created and the diff tool will show, allowing you to validate the tests result and copy it over to the approved file. For more detail, see How It Works

Having a diff tool pop up during an automated build is not ideal, so it can be disabled by setting the AssentNonInteractive environment variable to true.

Refer to the Wiki

.NET Core Cake build scripts from https://github.com/michael-wolfenden/dotnetcore-build

Inspiration is drawn from ApprovalTests, if you need a more powerful tool, and you are using the .NET Framework, it is worth a look.

AppVeyor for supporting OSS and providing free CI builds