ASP.Net Core unit testing async controller [duplicate]

Answer 1

Using the test classes from this answer :

How to mock an async repository with Entity Framework Core

The following generic extension method was derived

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

    var data = source.AsQueryable();

    var mockSet = new Mock>();

    mockSet.As>()
        .Setup(m => m.GetEnumerator())
        .Returns(new TestAsyncEnumerator(data.GetEnumerator()));

    mockSet.As>()
        .Setup(m => m.Provider)
        .Returns(new TestAsyncQueryProvider(data.Provider));

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

    return mockSet;
}

With the above extension method the test can be refactored to

[Fact]
public async Task Can_Paginate() {

    //Arrange

    var products = GetFakeProducts().ToAsyncDbSetMock();    
    var productCategories = GetFakeProductCategories().ToAsyncDbSetMock();

    var customDbContextMock = new Mock();
    customDbContextMock.Setup(x => x.Products).Returns(products.Object);
    customDbContextMock.Setup(x => x.ProductCategories).Returns(productCategories.Object);

    //...other code removed for brevity

    var controller = new ProductsController(customDbContextMock.Object, loggerMock.Object, envMock.Object);
    controller.pageSize = 3;
    controller.ControllerContext = new ControllerContext(actionContext);

    //Act
    var result = await controller.List(1, 2);

    //Assert

    //...other code removed for brevity
}