c# - 在使用 SQL 查询的单元测试中模拟 IDocumentQuery

Question

我正在使用单元测试来测试 DocumentDBRepository 类。我关注了this post作为 SQL 查询用例的示例。但它显示错误

Message: System.InvalidCastException : Unable to cast object of type 'System.Linq.EnumerableQuery to type 'Microsoft.Azure.Documents.Linq.IDocumentQuery

这是我的 DocumentDBRepository 类的代码

private IDocumentQuery<T> GetQueryBySQL(string queryStr)
{
    var uri = UriFactory.CreateDocumentCollectionUri(_databaseId, _collectionId);
    var feedOptions = new FeedOptions { MaxItemCount = -1, EnableCrossPartitionQuery = true };
    IQueryable<T> filter = _client.CreateDocumentQuery<T>(uri, queryStr, feedOptions); 
    IDocumentQuery<T> query = filter.AsDocumentQuery();
    return query;

}

public async Task<IEnumerable<T>> RunQueryAsync(string queryString)
{
    IDocumentQuery<T> query = GetQueryBySQL(queryString);

    List<T> results = new List<T>();

    while (query.HasMoreResults)
    {
        results.AddRange(await query.ExecuteNextAsync<T>());
    }
    return results;
}

这是我的测试类的代码

public async virtual Task Test_GetEntitiesAsyncBySQL()
{
    var id = "100";
    string queryString = "SELECT * FROM c WHERE c.ID = " + id;
    var dataSource = new List<Book> {
            new Book { ID = "100", Title = "abc"}}.AsQueryable();


    Expression<Func<Book, bool>> predicate = t => t.ID == id;
    var expected = dataSource.Where(predicate.Compile());
    var response = new FeedResponse<Book>(expected);

    var mockDocumentQuery = new Mock<DocumentDBRepositoryTest.IFakeDocumentQuery<Book>>();

    mockDocumentQuery
        .SetupSequence(_ => _.HasMoreResults)
        .Returns(true)
        .Returns(false);

    mockDocumentQuery
        .Setup(_ => _.ExecuteNextAsync<Book>(It.IsAny<CancellationToken>()))
        .ReturnsAsync(response);

    var provider = new Mock<IQueryProvider>();
    provider
        .Setup(_ => _.CreateQuery<Book>(It.IsAny<Expression>()))
        .Returns(mockDocumentQuery.Object);

    mockDocumentQuery.As<IQueryable<Book>>().Setup(x => x.Provider).Returns(provider.Object);
    mockDocumentQuery.As<IQueryable<Book>>().Setup(x => x.Expression).Returns(dataSource.Expression);
    mockDocumentQuery.As<IQueryable<Book>>().Setup(x => x.ElementType).Returns(dataSource.ElementType);
    mockDocumentQuery.As<IQueryable<Book>>().Setup(x => x.GetEnumerator()).Returns(() => dataSource.GetEnumerator());

    var client = new Mock<IDocumentClient>();

    client.Setup(_ => _.CreateDocumentQuery<Book>(It.IsAny<Uri>(), It.IsAny<FeedOptions>()))
          .Returns(mockDocumentQuery.Object);

    var documentsRepository = new DocumentDBRepository<Book>(client.Object, "100", "100");

    //Act
    var entities = await documentsRepository.RunQueryAsync(queryString);

    //Assert
    entities.Should()
        .NotBeNullOrEmpty()
        .And.BeEquivalentTo(expected);
}

断点停在这行代码:

IQueryable<T> filter = _client.CreateDocumentQuery<T>(uri, queryStr, feedOptions); 

当它应该显示我在测试方法中定义的预期值时，filter变量在其许多属性中显示空异常，并且结果 View 显示为空。

知道如何解决这个问题吗？

Answer 1

需要在模拟客户端上设置正确的 CreateDocumentQuery 重载。

被测方法使用

IQueryable<T> filter = _client.CreateDocumentQuery<T>(uri, queryStr, feedOptions); 

但是在安排测试时，客户端的设置如下

client
    .Setup(_ => _.CreateDocumentQuery<Book>(It.IsAny<Uri>(), It.IsAny<FeedOptions>()))
    .Returns(mockDocumentQuery.Object);

应该改为

client
    .Setup(_ => _.CreateDocumentQuery<Book>(It.IsAny<Uri>(), It.IsAny<string>(), It.IsAny<FeedOptions>()))
    .Returns(mockDocumentQuery.Object);

因为额外的queryStr参数。它也可以直接使用字符串参数作为替代方案，因为它被显式注入(inject)到方法中并且可以用作期望的一部分。

client
    .Setup(_ => _.CreateDocumentQuery<Book>(It.IsAny<Uri>(), queryStr, It.IsAny<FeedOptions>()))
    .Returns(mockDocumentQuery.Object);

由于正在测试的方法在构建查询时不直接使用 Linq，因此无需像本主题的先前迭代中那样模拟/覆盖查询提供程序

这是经过上述更改后完成的测试

public async virtual Task Test_GetEntitiesAsyncBySQL() {
    //Arrange
    var id = "100";
    string queryString = "SELECT * FROM c WHERE c.ID = " + id;
    var dataSource = new List<Book> {
        new Book { ID = "100", Title = "abc"}
    }.AsQueryable();

    Expression<Func<Book, bool>> predicate = t => t.ID == id;
    var expected = dataSource.Where(predicate.Compile());
    var response = new FeedResponse<Book>(expected);

    var mockDocumentQuery = new Mock<IFakeDocumentQuery<Book>>();

    mockDocumentQuery
        .SetupSequence(_ => _.HasMoreResults)
        .Returns(true)
        .Returns(false);

    mockDocumentQuery
        .Setup(_ => _.ExecuteNextAsync<Book>(It.IsAny<CancellationToken>()))
        .ReturnsAsync(response);

    //Note the change here
    mockDocumentQuery.As<IQueryable<Book>>().Setup(_ => _.Provider).Returns(dataSource.Provider);
    mockDocumentQuery.As<IQueryable<Book>>().Setup(_ => _.Expression).Returns(dataSource.Expression);
    mockDocumentQuery.As<IQueryable<Book>>().Setup(_ => _.ElementType).Returns(dataSource.ElementType);
    mockDocumentQuery.As<IQueryable<Book>>().Setup(_ => _.GetEnumerator()).Returns(() => dataSource.GetEnumerator());

    var client = new Mock<IDocumentClient>();

    //Note the change here
    client
        .Setup(_ => _.CreateDocumentQuery<Book>(It.IsAny<Uri>(), It.IsAny<string>(), It.IsAny<FeedOptions>()))
        .Returns(mockDocumentQuery.Object);

    var documentsRepository = new DocumentDBRepository<Book>(client.Object, "100", "100");

    //Act
    var entities = await documentsRepository.RunQueryAsync(queryString);

    //Assert
    entities.Should()
        .NotBeNullOrEmpty()
        .And.BeEquivalentTo(expected);
}