我可以创建一个我可以添加的模拟数据库上下文,然后搜索吗？

Question

我有一个简单的文档管理器,它在asp.net c#MVC项目中注入我的控制器.该项目是数据库优先的,Document表由documentId一个自动递增的整数索引.

我一直在尝试编写一个测试以测试以下实现的测试CreateNewDocument,在成功添加文档之后查找它并返回新的文档ID.

问题是我无法找到一种方法来模拟MyEntityFrameWorkEntities我可以添加文档然后使用linq搜索该文档.我认为它不起作用,因为嘲笑_context.Document.Add并没有真正做任何事情.

我的问题是这样的:我需要改变我的DocumentManager,这样的代码是可测试(例如通过更换.First用.FirstOrDefault和显示,如果返回null函数返回零),或可我(我应该)设置我的嘲笑不同,所以我能保持DocumentManager原样并写一个通过的测试？

public class DocumentManager : IDocumentManager
{
    private readonly MyEntityFrameWorkEntities _context;

    public DocumentManager(MyEntityFrameWorkEntities context)
    {
        _context = context;
    }

    public int CreateNewDocument(int userId)
    {
        var newDocumentGuid = Guid.NewGuid(); 
        var newDocument = new Document
        {
            UserId = userId,
            DateCreated = DateTime.Now,
            DocumentGuid = newDocumentGuid
        };
        _context.Document.Add(newDocument);
        _context.SaveChanges();
        // the .First here doesn't return anything when called from tests
        return _context.Document.First(d => d.DocumentGuid == newDocumentGuid).DocumentId;
    }
}

public partial class MyEntityFrameWorkEntities : DbContext
{
    public MyEntityFrameWorkEntities() : base("name=MyEntityFrameWorkEntities")
    {
    }

    public virtual DbSet<Document> Document { get; set; }
    /* ...etc... */
}

和测试类:

[TestMethod]
public void TestCreateNewDocument()
{
    var mockContext = new Mock<MyEntityFrameWorkEntities>();

    var mockDocumentDbSet = GetQueryableMockDocumentDbSet();

    mockContext.Setup(m => m.Document).Returns(mockDocumentDbSet.Object);

    var documentManager = new DocumentManager(mockContext.Object);

    var newDocId = documentManager.CreateNewDocument(123);

    // This line doesn't get hit as the .First falls over before here
    Assert.AreNotEqual(newDocId, 0);
}

private static Mock<DbSet<Document>> GetQueryableMockDocumentDbSet()
{
    var data = new List<Document> { GetDocument(111, 11), GetDocument(222, 22), GetDocument(333, 33) }.AsQueryable();
    var mockDocumentDbSet = new Mock<DbSet<Document>>();
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.Provider).Returns(data.Provider);
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.Expression).Returns(data.Expression);
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.ElementType).Returns(data.ElementType);
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());
    return mockDocumentDbSet;
}

private static Document GetDocument(int documentId, int userId)
{
    return new Document
    {
        DocumentId = documentId,
        UserId = userId,
        DateCreated = DateTime.Now.AddDays(-1),
        DocumentGuid = Guid.NewGuid(),
    };
}

Answer 1

您可以使用回调设置模拟DbSet的Add()方法,该回调会将项目添加到您的后备列表中:

private static Mock<DbSet<Document>> GetQueryableMockDocumentDbSet()
{
    var data = new List<Document> { GetDocument(111, 11), GetDocument(222, 22), GetDocument(333, 33) };

    var mockDocumentDbSet = new Mock<DbSet<Document>>();
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.Provider).Returns(data.AsQueryable().Provider);
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.Expression).Returns(data.AsQueryable().Expression);
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.ElementType).Returns(data.AsQueryable().ElementType);
    mockDocumentDbSet.As<IQueryable<Document>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());
    mockDocumentDbSet.Setup(m => m.Add(It.IsAny<Document>())).Callback<Document>(data.Add);
    return mockDocumentDbSet;

}

您随后对First()的调用应该能够检索该项目.