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AutoMapper cannot use TestDbAsyncEnumerable for IQueryable

I implemented fakes TestDbAsync https://msdn.microsoft.com/en-us/library/dn314429(v=vs.113).aspx , and I want AutoMapper to be able to use the project for a different type before calling Async EF (ToListAsync methods , CountAsync, etc.).

I get an exception exception in ProjectionExpression. For

Sample code that throws an exception.

_userRepository.GetAll().OrderBy(x => x.Id).ProjectTo<User>.ToListAsync();

This works fine in a non-test scenario, but when I mock DbSet using TestDbAsyncEnumerable, I get

: Unable to cast object of type 'Namespace.TestDbAsyncEnumerable`1[UserEntity]' to type 'System.Linq.IQueryable`1[User]'.

Now, to get around this, I need ProjectTo after calling the Async EF extensions. Is there a way to keep ProjectTo calling before EF extensions?

Link Code:

public class TestDbAsyncEnumerable<T> : EnumerableQuery<T>, IDbAsyncEnumerable<T>, IQueryable<T>
{
    public TestDbAsyncEnumerable(IEnumerable<T> enumerable)
        : base(enumerable)
    { }

    public TestDbAsyncEnumerable(Expression expression)
        : base(expression)
    { }

    public IDbAsyncEnumerator<T> GetAsyncEnumerator()
    {
        return new TestDbAsyncEnumerator<T>(this.AsEnumerable().GetEnumerator());
    }

    IDbAsyncEnumerator IDbAsyncEnumerable.GetAsyncEnumerator()
    {
        return GetAsyncEnumerator();
    }

    IQueryProvider IQueryable.Provider => new TestDbAsyncQueryProvider<T>(this);
}

public static Mock<DbSet<T>> ToAsyncDbSetMock<T>(this IEnumerable<T> source)
        where T : class
    {

        var data = source.AsQueryable();

        var mockSet = new Mock<DbSet<T>>();

        mockSet.As<IDbAsyncEnumerable<T>>()
            .Setup(m => m.GetAsyncEnumerator())
            .Returns(new TestDbAsyncEnumerator<T>(data.GetEnumerator()));

        mockSet.As<IQueryable<T>>()
            .Setup(m => m.Provider)
            .Returns(new TestDbAsyncQueryProvider<T>(data.Provider));

        mockSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(data.Expression);
        mockSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(data.ElementType);
        mockSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());

        return mockSet;
    }
+11
3

TestDbAsyncQueryProvider<>.CreateQuery() , , ProjectTo<>.

.

public IQueryable CreateQuery(Expression expression)
{
    switch (expression)
    {
        case MethodCallExpression m:
            {
                var resultType = m.Method.ReturnType; // it shoud be IQueryable<T>
                var tElement = resultType.GetGenericArguments()[0];
                var queryType = typeof(TestDbAsyncEnumerable<>).MakeGenericType(tElement);
                return (IQueryable)Activator.CreateInstance(queryType, expression);
            }
    }
    return new TestDbAsyncEnumerable<TEntity>(expression);
}

https://gist.github.com/masaedw/95ab972f8181de6bbe48a20ffe9be113

unit . .

https://github.com/masaedw/AutoMapper/blob/TestDbAsync/src/IntegrationTests/MockedContextTests.cs

+17

Automapper 6.0.2 6.1.1. 6.0.2.

, Automapper. , , github. .

+4

, CreateQuery, , - :

public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
{
    var queryType = typeof(TestDbAsyncEnumerable<>).MakeGenericType(typeof(TElement));
    return (IQueryable<TElement>)Activator.CreateInstance(queryType, expression);
}

TElement, .

+4

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