重构因类型而异的重复代码

Question

我构建了一些测试辅助方法，为 entity framework 构建了一个模拟 DBContext。这些方法包含重复代码，我假设必须有更好的方法来执行此操作。我只是想不通怎么办。我尝试创建 MockDbContextBuilder<> class，但失败了，因为我没有 DbSet<>。有任何想法吗？以下是我试图重构为一个方法的三个示例：

    private Mock<IPSNContext> BuildMockDbContext(List<TestEntity> list)
    {
        _mockDbSet = new Mock<DbSet<TestEntity>>();
        _mockDbSet.As<IQueryable<TestEntity>>().Setup(m => m.Provider).Returns(list.AsQueryable().Provider);
        _mockDbSet.As<IQueryable<TestEntity>>().Setup(m => m.Expression).Returns(list.AsQueryable().Expression);
        _mockDbSet.As<IQueryable<TestEntity>>().Setup(m => m.ElementType).Returns(list.AsQueryable().ElementType);
        _mockDbSet.As<IQueryable<TestEntity>>().Setup(m => m.GetEnumerator()).Returns(list.AsQueryable().GetEnumerator());

        foreach (var item in list)
        {
            _mockDbSet.Setup(m => m.Find(item.Id)).Returns(item);
        }

        var mockContext = new Mock<IPSNContext>();
        mockContext.Setup(c => c.Set<TestEntity>())
                    .Returns(_mockDbSet.Object);
        return mockContext;
    }

    private Mock<IPSNContext> BuildMockDbContext(List<MessageBoardTopic> list)
    {
        _mockDbSet = new Mock<DbSet<MessageBoardTopic>>();
        _mockDbSet.As<IQueryable<MessageBoardTopic>>().Setup(m => m.Provider).Returns(list.AsQueryable().Provider);
        _mockDbSet.As<IQueryable<MessageBoardTopic>>().Setup(m => m.Expression).Returns(list.AsQueryable().Expression);
        _mockDbSet.As<IQueryable<MessageBoardTopic>>().Setup(m => m.ElementType).Returns(list.AsQueryable().ElementType);
        _mockDbSet.As<IQueryable<MessageBoardTopic>>().Setup(m => m.GetEnumerator()).Returns(list.AsQueryable().GetEnumerator());

        foreach (var item in list)
        {
            _mockDbSet.Setup(m => m.Find(item.Id)).Returns(item);
        }

        var mockContext = new Mock<IPSNContext>();
        mockContext.Setup(c => c.Set<MessageBoardTopic>())
                    .Returns(_mockDbSet.Object);        
        return mockContext;
    }

    private Mock<IPSNContext> BuildMockDbContext(List<MessageBoardReply> list)
    {
        _mockDbSet = new Mock<DbSet<MessageBoardReply>>();
        _mockDbSet.As<IQueryable<MessageBoardReply>>().Setup(m => m.Provider).Returns(list.AsQueryable().Provider);
        _mockDbSet.As<IQueryable<MessageBoardReply>>().Setup(m => m.Expression).Returns(list.AsQueryable().Expression);
        _mockDbSet.As<IQueryable<MessageBoardReply>>().Setup(m => m.ElementType).Returns(list.AsQueryable().ElementType);
        _mockDbSet.As<IQueryable<MessageBoardReply>>().Setup(m => m.GetEnumerator()).Returns(list.AsQueryable().GetEnumerator());

        foreach (var item in list)
        {
            _mockDbSet.Setup(m => m.Find(item.Id)).Returns(item);
        }

        var mockContext = new Mock<IPSNContext>();
        mockContext.Setup(c => c.Set<MessageBoardReply>())
                    .Returns(_mockDbSet.Object);
        return mockContext;
    }

Answer 1

您可以使用泛型类型的方法，例如：

    private Mock<IPSNContext> BuildMockDbContext<T>(List<T> list)
    {
                _mockDbSet = new Mock<DbSet<T>>();
                _mockDbSet.As<IQueryable<T>>().Setup(m => m.Provider).Returns(list.AsQueryable().Provider);
                _mockDbSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(list.AsQueryable().Expression);
                _mockDbSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(list.AsQueryable().ElementType);
                _mockDbSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(list.AsQueryable().GetEnumerator());

                foreach (var item in list)            
                    _mockDbSet.Setup(m => m.Find(item.Id)).Returns(item);            

                var mockContext = new Mock<IPSNContext>();
                mockContext.Setup(c => c.Set<MessageBoardTopic>())
                            .Returns(_mockDbSet.Object);

                return mockContext;
   }

重构因类型而异的重复代码

Refactoring duplicate code that differs by type

c#

oop

generics

inheritance

refactoring