title: "Mocking Entity Framework when Unit Testing ASP.NET Web API 2 | Microsoft Docs"
author: tfitzmac
description: "This guidance and application demonstrate how to create unit tests for your Web API 2 application that uses the Entity Framework. It shows how to modify the..."
> This guidance and application demonstrate how to create unit tests for your Web API 2 application that uses the Entity Framework. It shows how to modify the scaffolded controller to enable passing a context object for testing, and how to create test objects that work with Entity Framework.
>
> For an introduction to unit testing with ASP.NET Web API, see [Unit Testing with ASP.NET Web API 2](unit-testing-with-aspnet-web-api.md).
>
> This tutorial assumes you are familiar with the basic concepts of ASP.NET Web API. For an introductory tutorial, see [Getting Started with ASP.NET Web API 2](../getting-started-with-aspnet-web-api/tutorial-your-first-web-api.md).
>
> ## Software versions used in the tutorial
>
>
> - [Visual Studio 2013](https://www.microsoft.com/visualstudio/eng/2013-downloads)
> - Web API 2
## In this topic
This topic contains the following sections:
- [Prerequisites](#prereqs)
- [Download code](#download)
- [Create application with unit test project](#appwithunittest)
- [Create the model class](#modelclass)
- [Add the controller](#controller)
- [Add dependency injection](#dependency)
- [Install NuGet packages in test project](#testpackages)
- [Create test context](#testcontext)
- [Create tests](#tests)
- [Run tests](#runtests)
If you have already completed the steps in [Unit Testing with ASP.NET Web API 2](unit-testing-with-aspnet-web-api.md), you can skip to the section [Add the controller](#controller).
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## Prerequisites
Visual Studio 2013 or Visual Studio Express 2013 for Web
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## Download code
Download the [completed project](https://code.msdn.microsoft.com/Unit-Testing-with-ASPNET-e2867d4d). The downloadable project includes unit test code for this topic and for the [Unit Testing ASP.NET Web API 2](unit-testing-with-aspnet-web-api.md) topic.
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## Create application with unit test project
You can either create a unit test project when creating your application or add a unit test project to an existing application. This tutorial shows creating a unit test project when creating the application.
Create a new ASP.NET Web Application named **StoreApp**.
In the New ASP.NET Project windows, select the **Empty** template and add folders and core references for Web API. Select the **Add unit tests** option. The unit test project is automatically named **StoreApp.Tests**. You can keep this name.
After creating the application, you will see it contains two projects - **StoreApp** and **StoreApp.Tests**.
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## Create the model class
In your StoreApp project, add a class file to the **Models** folder named **Product.cs**. Replace the contents of the file with the following code.
Click **Add** to create the controller with automatically-generated code. The code includes methods for creating, retrieving, updating and deleting instances of the Product class. The following code shows the method for add a Product. Notice that the method returns an instance of **IHttpActionResult**.
IHttpActionResult is one of the new features in Web API 2, and it simplifies unit test development.
In the next section, you will customize the generated code to facilitate passing test objects to the controller.
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## Add dependency injection
Currently, the ProductController class is hard-coded to use an instance of the StoreAppContext class. You will use a pattern called dependency injection to modify your application and remove that hard-coded dependency. By breaking this dependency, you can pass in a mock object when testing.
Right-click the **Models** folder, and add a new interface named **IStoreAppContext**.
Open the ProductController.cs file. Change the existing code to match the highlighted code. These changes break the dependency on StoreAppContext and enable other classes to pass in a different object for the context class. This change will enable you to pass in a test context during unit tests.
There is one more change you must make in ProductController. In the **PutProduct** method, replace the line that sets the entity state to modified with a call to the MarkAsModified method.
When you use the Empty template to create an application, the unit test project (StoreApp.Tests) does not include any installed NuGet packages. Other templates, such as the Web API template, include some NuGet packages in the unit test project. For this tutorial, you must include the Entity Framework packge and the Microsoft ASP.NET Web API 2 Core package to the test project.
Right-click the StoreApp.Tests project and select **Manage NuGet Packages**. You must select the StoreApp.Tests project to add the packages to that project.
From the Online packages, find and install the EntityFramework package (version 6.0 or later). If it appears that the EntityFramework package is already installed, you may have selected the StoreApp project instead of the the StoreApp.Tests project.
Find and install Microsoft ASP.NET Web API 2 Core package.
Close the Manage NuGet Packages window.
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## Create test context
Add a class named **TestDbSet** to the test project. This class serves as the base class for your test data set. Replace the code with the following code.
By default, your test project includes an empty test file named **UnitTest1.cs**. This file shows the attributes you use to create test methods. For this tutorial, you can delete this file because you will add a new test class.
Add a class named **TestProductController** to the test project. Replace the code with the following code.
You are now ready to run the tests. All of the method that are marked with the **TestMethod** attribute will be tested. From the **Test** menu item, run the tests.
