C# : How to unit test Graph SDK Batch Request

Even though writing unit tests for Azure Graph SDK became easier, writing unit test for Batch request was little bit confusing to me.

Source Code

This is my class which I want to write unit test. I omit some business logic on purpose, this is not simple wrapper in real project.

DI GraphServiceClient
Return User objects via Batch Request
Use AddBatchRequestStep to control requestId

public class GraphService
{
    private readonly GraphServiceClient graphServiceClient;

    public GraphService(GraphServiceClient graphServiceClient)
    {
        this.graphServiceClient = graphServiceClient;
    }

    public async Task<List<User>> GetUsersAsync(List<string> userIds)
    {
        List<User> users = new();
        BatchRequestContent batchRequestContent = new();
        userIds.ForEach(x =>
        {
            batchRequestContent.AddBatchRequestStep(new BatchRequestStep(x, graphServiceClient.Users[x]
                    .Request().Select(u => new
                    {
                        u.Id,
                        u.GivenName,
                        u.Mail,
                        u.Surname,
                        u.UserPrincipalName
                    }).GetHttpRequestMessage()));
        });

        BatchResponseContent returnedResponse = await graphServiceClient.Batch.Request().PostAsync(batchRequestContent);
        userIds.ForEach(async x =>
        {
            User user = await returnedResponse.GetResponseByIdAsync<Microsoft.Graph.User>(x);
            users.Add(user);
        });

        return users;
    }
}

Unit Test Code

I don't know if there is better way to achieve the same, but this is what I did by following advice in GitHub issue

Create response as json string
Mock IHttpProvider to handle SendAsync request. Return the json string as StringContent
Mock GraphServiceClient ahd pass mocked IHttpProvider as constructor
Mock GetHttpRequestMessage method as this is called in AddBatchRequestStep

[Fact]
public async Task ReturnsUsers()
{
    // Arrenge
    string userId = "dummy_id1";
    string userId2 = "dummy_id2";
    string batchResponse = @$"{{
""responses"":[{{
    ""id"": ""{userId}"",
    ""status"":200,
    ""headers"":
    {{
        ""Content-Type"":""application/json""
    }},
    ""body"":
    {{
        ""@odata.context"":""https://graph.microsoft.com/v1.0/$metadata#users/$entity"",
        ""surName"":""Test"",
        ""givenName"":""User1"",
        ""id"":""{userId}""
    }}
  }},
{{
    ""id"": ""{userId2}"",
    ""status"":200,
    ""headers"":
    {{
        ""Content-Type"":""application/json""
    }},
    ""body"":
    {{
        ""@odata.context"":""https://graph.microsoft.com/v1.0/$metadata#users/$entity"",
        ""surName"":""Test"",
        ""givenName"":""User2"",
        ""id"":""{userId2}""
    }}
  }}]
}}";
    Mock<IHttpProvider> mockedIHttpProvider = new();
    mockedIHttpProvider.Setup(x => x.SendAsync(
        It.IsAny<HttpRequestMessage>(), 
        It.IsAny<HttpCompletionOption>(), 
        It.IsAny<CancellationToken>()))
        .ReturnsAsync(new HttpResponseMessage()
        {
            StatusCode = HttpStatusCode.OK,
            Content = new StringContent(batchResponse),
        });
    Mock<IAuthenticationProvider> mockedIAuthenticationProvider = new();
    Mock<GraphServiceClient> mockedGraphServiceClient = new(
        mockedIAuthenticationProvider.Object, mockedIHttpProvider.Object);
    mockedGraphServiceClient.Setup(x => x.Users[It.IsAny<string>()]
        .Request()
        .Select(It.IsAny<Expression<Func<Microsoft.Graph.User, object>>>()).GetHttpRequestMessage())
        .Returns(new HttpRequestMessage() { RequestUri = new Uri("http://localhost/v1.0/users") });
    GraphService graphService = new(mockedGraphServiceClient.Object);

    // Act
    List<User> users = await graphService.GetUsersAsync(new List<string>() { userId, userId2 }).ConfigureAwait(false);

    // Assert
    Assert.True(users.Count == 2);
}