[英]Mocking async DbContext functions with input parameter with C#/Moq Framework
我做了一個DbContext的模擬,並填充了測試數據。 DbSet是一個受保護的類,因此無法模擬結果,因此我找到了擴展方法。
public static class DbSetMocking
{
private static Mock<DbSet<T>> CreateMockSet<T>(IQueryable<T> data)
where T : class
{
var queryableData = data.AsQueryable();
var mockSet = new Mock<DbSet<T>>();
mockSet.As<IQueryable<T>>().Setup(m => m.Provider)
.Returns(queryableData.Provider);
mockSet.As<IQueryable<T>>().Setup(m => m.Expression)
.Returns(queryableData.Expression);
mockSet.As<IQueryable<T>>().Setup(m => m.ElementType)
.Returns(queryableData.ElementType);
mockSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator())
.Returns(queryableData.GetEnumerator());
return mockSet;
}
public static IReturnsResult<TContext> ReturnsDbSet<TEntity, TContext>(this IReturns<TContext, DbSet<TEntity>> setup, TEntity[] entities)
where TEntity : class
where TContext : DbContext
{
var mockSet = CreateMockSet(entities.AsQueryable());
return setup.Returns(mockSet.Object);
}
public static IReturnsResult<TContext> ReturnsDbSet<TEntity, TContext>(this IReturns<TContext, DbSet<TEntity>> setup, IQueryable<TEntity> entities)
where TEntity : class
where TContext : DbContext
{
var mockSet = CreateMockSet(entities);
return setup.Returns(mockSet.Object);
}
public static IReturnsResult<TContext> ReturnsDbSet<TEntity, TContext>(this IReturns<TContext, DbSet<TEntity>> setup, IEnumerable<TEntity> entities)
where TEntity : class
where TContext : DbContext
{
var mockSet = CreateMockSet(entities.AsQueryable());
return setup.Returns(mockSet.Object);
}
}
創建一個DbContext模擬:
var db = new Mock<DbContext>();
//Populate
this.db.Setup(x => x.MyObjects).ReturnsDbSet(
new List<MyObject>
{
new MyObject{Id=1, Description="Test"},
}
);
其次,我正在嘗試將Mocks擴展為包括Find(id)和FindAsync(id)方法。 這些方法位於DbSetMocking類中。 查找方法工作正常:
mockSet.Setup(m => m.Find(It.IsAny<object[]>()))
.Returns<object[]>(id => StaticMethodtoFindStuff<T>(queryableData, id));
但是,我無法使FindAsync方法正常工作。 到目前為止,這是我嘗試過的:
mockSet.Setup(m => m.FindAsync(It.IsAny<object[]>()))
.Returns(Task.FromResult(StaticMethodtoFindStuff<T>(queryableData, 1)));
此功能有效,但隨后我無法訪問該函數設置的參數。 嘗試了這一操作,編譯工作正常,但執行失敗,並顯示錯誤msg:
類型'System.Object []'的對象不能轉換為類型'System.Threading.Tasks.Task`1 [System.Object []]'。
mockSet.Setup(m => m.FindAsync(It.IsAny<object[]>()))
.Returns<Task<object[]>>(d =>
{
return Task.FromResult(StaticMethodtoFindStuff<T>(queryableData, d));
});
有人知道如何實現此功能嗎?
嘗試更改此行:
mockSet.Setup(m => m.FindAsync(It.IsAny<object[]>()))
.Returns<Task<object[]>>(d =>
{
return Task.FromResult(StaticMethodtoFindStuff<T>(queryableData, d));
});
至:
mockSet.Setup(m => m.FindAsync(It.IsAny<object[]>()))
.Returns<object[]>(d =>
{
return Task.FromResult(StaticMethodtoFindStuff<T>(queryableData, d));
});
這里的問題是, .Returns<T>
通用參數T
不是結果的類型,而是那是在.Setup
方法中傳遞給函數的第一個參數的類型-對於您的對象是[]。
查看Moq源代碼以獲取更多信息:
這是來源的引文,請檢查T1和T2參數注釋:
/// <summary>
/// Specifies a function that will calculate the value to return from the method,
/// retrieving the arguments for the invocation.
/// </summary>
/// <typeparam name="T1">The type of the first argument of the invoked method.</typeparam>
/// <typeparam name="T2">The type of the second argument of the invoked method.</typeparam>
/// <param name="valueFunction">The function that will calculate the return value.</param>
/// <return>Returns a calculated value which is evaluated lazily at the time of the invocation.</return>
/// <example>
/// <para>
/// The return value is calculated from the value of the actual method invocation arguments.
/// Notice how the arguments are retrieved by simply declaring them as part of the lambda
/// expression:
/// </para>
/// <code>
/// mock.Setup(x => x.Execute(
/// It.IsAny<int>(),
/// It.IsAny<int>()))
/// .Returns((int arg1, int arg2) => arg1 + arg2); //I fixed that line, it's different in the documentation and is incorrect
/// </code>
/// </example>
IReturnsResult<TMock> Returns<T1, T2>(Func<T1, T2, TResult> valueFunction);
您還可以看到,它使用可變數目的泛型參數定義了多個Returns重載,因此您可以模擬最多包含16個參數的方法。
終於弄明白了。 原來我在那里缺少一個“異步”關鍵字。 代碼是:
mockSet.Setup(m => m.FindAsync(It.IsAny<object[]>()))
.Returns<object[]>(async (d) =>
{
return await Task.FromResult(StaticMethodtoFindStuff<T>(queryableData, d));
});
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