How to use Moq to satisfy a MEF import dependency for unit testing?

Question

This is my interface

public interface IWork
{
    string GetIdentifierForItem(Information information);
}

and my class

publ         


        

Answer 1

You don't need to Mock the Lazy<T,TMetadta>. It is flexible enough to work with your test. Instead, Mock the IWindowTypeInfo

[TestMethod]
public void GetIDTest()
{
    var windowTypeInfoMock = new Mock<IWindowTypeInfo>();
    windowTypeInfoMock.Setup(foo => foo.Name).Returns("Data");
    windowTypeInfoMock.Setup(foo => foo.UniqueID).Returns("someString");
    var lazyWindow =
         new Lazy<IWindowType, IWindowTypeInfo>(windowTypeInfoMock.Object);

    var WindowTypesList = new List<Lazy<IWindowType, IWindowTypeInfo>>();
    WindowTypesList.Add(lazyWindow);

    var a = new A();
    a.WindowTypes = WindowTypesList;
    var InfoMock = new Mock<Information>();
    InfoMock.Setup(foo => foo.TargetName).Returns("Data");

    string expected = "someString";
    string actual;
    actual = a.GetIdentifierForItem(InfoMock.Object);
    Assert.AreEqual(expected, actual);
}

Your test passes on my machine with only small modifications, you do not need to use a composition container for this test.

Answer 2

This is how it may be done, after setting up the mocks

1) Creating a CompositionContainer, that holds the imports.

2) Adding Mocks to the container.

container.ComposeExportedValue(mock.Object);

3) Create an instance of tested class

4) Compose mocks to the import

container.ComposeParts(instance);