单元测试项目坚持要求引用EntityFramework

Question

I have an issue that just came up in a unit test project insisting that it requires a reference of EntityFramework, I am convinced it doesn't need it. Other projects are referencing the project/extension method that the unit test project is referencing/testing and using the extension method just fine without a reference to EntityFramework.

I have found that if I simply execute the extension method as a static method in the unit test project then the unit test project compiles just fine – just completely baffled. I did not see anything informative in the build output.

This does not compile:

[TestMethod]
public void BuildsEmptyRadioButtonList()
{
    var htmlHelper = Creator.GetHelper();

    var radioButtonList = htmlHelper.RadioButtonList("RadioGaga", new SelectListItem[0]);

    var expected = MvcHtmlString.Create(@"...");
    Assert.AreEqual(expected.ToHtmlString(), radioButtonList.ToHtmlString());
}

Build output:

1>------ Build started: Project: HA.Shared.Utilities.Mvc.Tests, Configuration: Debug Any CPU ------
1>C:\hatfs\Web2014\4-Test\Source\HA.Shared.Utilities.Mvc.Tests\HtmlHelperRadioExtensionsTests.cs(25,17,25,20): error CS0012: The type 'System.Data.Entity.IDbSet`1<T0>' is defined in an assembly that is not referenced. You must add a reference to assembly 'EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
========== Build: 0 succeeded, 1 failed, 8 up-to-date, 0 skipped ==========

The error is pointing to the “var” in the line that starts with “var radioButtonList”, I tried changing the “var” to “IHtmlString” with no change.

This does compile:

[TestMethod]
public void BuildsEmptyRadioButtonList()
{
    var htmlHelper = Creator.GetHelper();

    var radioButtonList = HtmlHelperRadioExtensions.RadioButtonList(htmlHelper, "RadioGaga", new SelectListItem[0]);

    var expected = MvcHtmlString.Create(@"...");
    Assert.AreEqual(expected.ToHtmlString(), radioButtonList.ToHtmlString());
}

Build output:

1>------ Build started: Project: HA.Shared.Utilities.Mvc.Tests, Configuration: Debug Any CPU ------
1>  HA.Shared.Utilities.Mvc.Tests -> C:\hatfs\Web2014\4-Test\Source\HA.Shared.Utilities.Mvc.Tests\bin\Debug\HA.Shared.Utilities.Mvc.Tests.dll
========== Build: 1 succeeded, 0 failed, 8 up-to-date, 0 skipped ==========

The signature of the RadioButtonList method is: public static MvcHtmlString RadioButtonList( this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> listItems, object radioButtonHtmlAttributes = null, object labelHtmlAttributes = null, bool vertical = false)

Answer 1

I just figured out the issue. I recently added an extension method ReturnsSet (below), to more easily mock IDbSet s off of DbContext s in a shared unit test "helpers" project. Though I do not know why, apparently the compiler still felt that it needed a reference to EntityFramework to compile the specific project where the issue arose. When I comment out the new ReturnsSet extension method, the specific unit test project compiles using the extension method form of syntax.

using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data.Entity;
using System.Linq;

using Moq;
using Moq.Language.Flow;

public static class DbMockHelpers
{
    public static Mock<IDbSet<TEntity>> MockSingle<TEntity>(TEntity data) 
        where TEntity : class, new()
    {
        return MockDbSet(new[] { data });
    }

    public static Mock<IDbSet<TEntity>> MockDbSet<TEntity>(params TEntity[] data)
        where TEntity : class, new()
    {
        return MockDbSet(data.AsEnumerable());
    }

    public static Mock<IDbSet<TEntity>> MockDbSet<TEntity>(IEnumerable<TEntity> data) 
        where TEntity : class, new()
    {
        var list = data == null ? new List<TEntity>() : data.ToList();
        var observable = new ObservableCollection<TEntity>(list);
        var dbSet = new Mock<IDbSet<TEntity>>();
        dbSet.Setup(d => d.Add(It.IsAny<TEntity>())).Callback((TEntity entity) => list.Add(entity));
        dbSet.Setup(d => d.Remove(It.IsAny<TEntity>())).Callback((TEntity entity) => list.Remove(entity));
        dbSet.Setup(d => d.Attach(It.IsAny<TEntity>())).Callback((TEntity entity) => list.Add(entity));
        dbSet.Setup(d => d.Create()).Returns(new TEntity());
        dbSet.Setup(d => d.GetEnumerator()).Returns(() => list.GetEnumerator());
        dbSet.Setup(d => d.Local).Returns(observable);
        dbSet.Setup(d => d.ElementType).Returns(typeof(TEntity));
        dbSet.Setup(d => d.Provider).Returns(list.AsQueryable().Provider);
        dbSet.Setup(d => d.Expression).Returns(list.AsQueryable().Expression);
        return dbSet;
    } 

    public static IDbSet<TEntity> DbSet<TEntity>(IEnumerable<TEntity> data) 
        where TEntity : class, new()
    {
        return MockDbSet(data).Object;
    }

    public static IDbSet<TEntity> DbSet<TEntity>(params TEntity[] data)
        where TEntity : class, new()
    {
        return MockDbSet(data).Object;
    }

    // commenting out this method allowed the project to compile without the reference to EF
    public static IReturnsResult<T> ReturnsSet<T, TProperty, TEntity>(this ISetupGetter<T, TProperty> setupGetter, params TEntity[] data)
        where T : class
        where TProperty : IDbSet<TEntity>
        where TEntity : class, new()
    {
        return setupGetter.Returns((TProperty)DbSet(data));
    }
}