Mocking Entity Framework for your Unit Tests using NBuilder

If you need to Mock Entity Framework in your Unit Tests you may end up referring to this article: https://msdn.microsoft.com/en-us/library/dn314429.aspx

In the article, they require you to create a test collection of your DbSet objects which are subsequently passed to your DbContext instance.

In addition, if you have multiple DbSet objects which are involved in a particular query, then this increases your workload even further!

However, you can use a framework such as NBuilder which is available as a NuGet package in order to simplify some of this code for you:

	var mockSet1 = new Mock<DbSet<Table1>>();
	var mockSet2 = new Mock<DbSet<Table2>>();
	var mockSet3 = new Mock<DbSet<Table3>>();
	var mockSet4 = new Mock<DbSet<Table4>>();
	var mockContext = new Mock<MyDbContext>(ConnectionString);
	var table1List = Builder<Table1>
	.CreateListOfSize(ListSize)
	.Build().AsQueryable();
	var table2List = Builder<Table2>
	.CreateListOfSize(ListSize)
	.Build().AsQueryable();
	var table3List = Builder<Table3>
	.CreateListOfSize(ListSize)
	.Build().AsQueryable();
	var table4List = Builder<Table4>
	.CreateListOfSize(ListSize)
	.Build().AsQueryable();
	mockSet1.As<IQueryable<Table1>>().Setup(m => m.Provider).Returns(table1List.Provider);
	mockSet1.As<IQueryable<Table1>>().Setup(m => m.Expression).Returns(table1List.Expression);
	mockSet1.As<IQueryable<Table1>>().Setup(m => m.ElementType).Returns(table1List.ElementType);
	mockSet1.As<IQueryable<Table1>>().Setup(m => m.GetEnumerator()).Returns(table1List.GetEnumerator());
	mockSet2.As<IQueryable<Table2>>().Setup(m => m.Provider).Returns(table2List.Provider);
	mockSet2.As<IQueryable<Table2>>().Setup(m => m.Expression).Returns(table2List.Expression);
	mockSet2.As<IQueryable<Table2>>().Setup(m => m.ElementType).Returns(table2List.ElementType);
	mockSet2.As<IQueryable<Table2>>().Setup(m => m.GetEnumerator()).Returns(table2List.GetEnumerator());
	mockSet3.As<IQueryable<Table3>>().Setup(m => m.Provider).Returns(table3List.Provider);
	mockSet3.As<IQueryable<Table3>>().Setup(m => m.Expression).Returns(table3List.Expression);
	mockSet3.As<IQueryable<Table3>>().Setup(m => m.ElementType).Returns(table3List.ElementType);
	mockSet3.As<IQueryable<Table3>>().Setup(m => m.GetEnumerator()).Returns(table3List.GetEnumerator());
	mockSet4.As<IQueryable<Table4>>().Setup(m => m.Provider).Returns(table4List.Provider);
	mockSet4.As<IQueryable<Table4>>().Setup(m => m.Expression).Returns(table4List.Expression);
	mockSet4.As<IQueryable<Table4>>().Setup(m => m.ElementType).Returns(table4List.ElementType);
	mockSet4.As<IQueryable<Table4>>().Setup(m => m.GetEnumerator()).Returns(table4List.GetEnumerator());
	mockContext.Setup(m => m.Table1).Returns(mockSet1.Object);
	mockContext.Setup(m => m.Table2).Returns(mockSet2.Object);
	mockContext.Setup(m => m.Table3).Returns(mockSet3.Object);
	mockContext.Setup(m => m.Table4).Returns(mockSet4.Object);

view raw MockingEntityFramework.cs hosted with ❤ by GitHub

Alternatively, you can use some NuGet packages which takes away some of the extra setup for Mocking Entity Framework such as the following:

https://github.com/RichardSilveira/EntityFramework.MoqHelper

https://github.com/scott-xu/EntityFramework.Testing