gistfile1.cs

[Fact]
public Task Fetch_WithBlogSelectedAndOneResult_DisplaysOnePost()
{
    // arrange
    var result = new[] { new Post() };

    metaWeblogService
         .GetRecentPostsAsync(Arg.Any<BlogSetting>(), Arg.Any<int>())
         .Returns(()=>Task.Factory.FromResult(new []{new Post()});

    subject.SelectedBlog = new BlogSetting();

    // act
    return subject
        .Fetch()
        .ContinueWith(t=>Assert.NotEmpty(subject.Posts));
}