余小章 @ 大內殿堂

此篇是研究性質，不建議 Mock EF

打從 EF6 開始，就可以使用 Mock Framework 來進行 DbSet 測試，下篇是使用 moq

https://msdn.microsoft.com/en-us/data/dn314429.aspx

我想把它換成 NSubstitute

我需要模擬兩各物件，DbContext、DbSet，比較麻煩的是DbSet，需要模擬四個方法

1. Provider
2. Expression
3. ElementType
4. GetEnumerator()

Mock DbSet：

var data = new List<Employee>()
{
    new Employee() { EmployeeID = 1, LastName = "余", FirstName = "小章" },
    new Employee() { EmployeeID = 2, LastName = "王", FirstName = "小華" },
    new Employee() { EmployeeID = 3, LastName = "蔡", FirstName = "比巴" },
}.AsQueryable();

var mockDbSet = Substitute.For<IDbSet<Employee>, DbSet<Employee>>();
mockDbSet.Provider.Returns(data.Provider);
mockDbSet.Expression.Returns(data.Expression);
mockDbSet.ElementType.Returns(data.ElementType);
mockDbSet.GetEnumerator().Returns(data.GetEnumerator()); 

 

Mock DbContext：

var mockDbContext = Substitute.For<NorthwindDbContext>();
mockDbContext.Employees.Returns(mockDbSet);

 

把這4個成員用擴充方法包起來

public static class ExtentionMethods
{
    public static IDbSet<T> Initialize<T>(this IDbSet<T> dbSet, IQueryable<T> data) where T : class
    {
        dbSet.Provider.Returns(data.Provider);
        dbSet.Expression.Returns(data.Expression);
        dbSet.ElementType.Returns(data.ElementType);
        dbSet.GetEnumerator().Returns(data.GetEnumerator());
        return dbSet;
    }
} 

 

完整程式碼：

https://dotblogsamples.codeplex.com/SourceControl/latest#Simple.RadGridPaging/UnitTestProject1/UnitTest1.cs

[TestMethod]
public void Mock_DbContext()
{
    //arrange
    var data = new List<Employee>()
    {
        new Employee() { EmployeeID = 1, LastName = "余", FirstName = "小章" },
        new Employee() { EmployeeID = 2, LastName = "王", FirstName = "小華" },
        new Employee() { EmployeeID = 3, LastName = "蔡", FirstName = "比巴" },
    }.AsQueryable();

    //var mockDbSet = Substitute.For<IDbSet<Employee>, DbSet<Employee>>();
    //mockDbSet.Provider.Returns(data.Provider);
    //mockDbSet.Expression.Returns(data.Expression);
    //mockDbSet.ElementType.Returns(data.ElementType);
    //mockDbSet.GetEnumerator().Returns(data.GetEnumerator());

    var mockDbSet = Substitute.For<IDbSet<Employee>, DbSet<Employee>>().Initialize(data);

    var mockDbContext = Substitute.For<NorthwindDbContext>();
    mockDbContext.Employees.Returns(mockDbSet);

    //act
    var query = mockDbContext.Employees.FirstOrDefault(p => p.EmployeeID == 2);

    //assert
    Assert.AreEqual("小華", query.FirstName);
} 

 

NSubstistute 越看越順眼

文章出自：https://www.dotblogs.com.tw/yc421206/2015/02/16/149502

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