Mock Elasticsearch client in NEST having problem with async search method

Question

I am using NEST framework to do elastic search query in c#.

I am writing a simple unit test with Moq.

mockElasticClient.Setup(ec => ec.SearchAsync(
                                    It.IsAny<Func<SearchDescriptor<Relativity>,
                                            SearchDescriptor<Relativity>>>()))
                                    .ReturnsAsync(mockSearchResponse.Object);

THe above code throws 'An expression tree may not contain a call or invocation that uses optional arguments'

the above code is working if i use Search instead of SearchAsync.

What am i doing wrong here?

Answer 1

All the parameters in a mocked function should be accounted for. In this case as from the function definition

    //
    // Parameters:
    //   selector:
    //     A descriptor that describes the parameters for the search operation
    //
    // Type parameters:
    //   T:
    //     The type used to infer the index and typename as well describe the query strongly
    //     typed
    Task<ISearchResponse<T>> SearchAsync<T>(Func<SearchDescriptor<T>, ISearchRequest> selector = null, CancellationToken cancellationToken = default) where T : class;

there are two parameters Func<SearchDescriptor, ISearchRequest>selector, and CancellationToken.

Mocking required that the CancellationToken Mocked as here below

mockElasticClient.Setup(x => x
            .SearchAsync(It.IsAny<Func<SearchDescriptor<Relativity>, ISearchRequest>>(),It.IsAny<CancellationToken>()))
            .ReturnsAsync(mockSearchResponse.Object);