I have a typed httpclient that I am injecting in my application using the HttpClientFactory extension methods for services in Program.cs

My client looks something like this with the HttpClient injected via the constructor:

public class MyClient
{
    private readonly HttpClient _httpClient;
    public MyClient(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public async Task<string> GetStuffFromApi()
    {
        // method to get content from API
        // return stuff
    }
}

The relevant section in Program.cs looks something like this for example:

        services.AddHttpClient<IMyClient, MyClient>(client =>
        {
            client.BaseAddress = new Uri("https://somewebsite.com/api");
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/plain"));
        }).AddPolicyHandler(MyClientPolicies.GetRetryAsyncPolicy());

I would like to test the retry policy among other things for this client. I found a great mockhttp library that is helpful for the mock client setup (MockHttp), but I am unsure of exactly what I need to do in order to include the retry policy behavior in my mocked client.

So the test looks something like this using XUnit currently:

public class MyClientTests
{
    [Fact]
    public async Task MyClient_RetriesRequest_OnTransientErrors()
    {
        // Arrange
        var mockHttp = new MockHttpMessageHandler();
        mockHttp.When("*").Respond(HttpStatusCode.RequestTimeout);
        var mockClient = new MyClient(mockHttp.ToHttpClient());
        // Act
        // ... call the method
        // Assert
        // ... assert the request was tried multiple times
    }
}

How do I test my mock http client including the additional configuration from Program.cs like the baseaddress and retry policies?

CodePudding user response：

You cannot test the retry policy if it's setup like that, in a simple unit test. You have 2 choices.

1. To create full-service integration tests and then get creative with mock services, following this guideline for integration tests from Microsoft: https://learn.microsoft.com/en-us/aspnet/core/test/integration-tests?view=aspnetcore-7.0#inject-mock-services.

2.To use the retry policy directly in your method which you are testing. Something like:

public async Task<string> GetStuffFromApi()
{
    var policy = MyClientPolicies.GetRetryAsyncPolicy()
    await policy.ExecuteAsync(async ctx =>

        var request = new HttpRequestMessage(HttpMethod.Get, new Uri("https://www.example.com"));
        var response = await _client.SendAsync(request);
        response.EnsureSuccessStatusCode();

        return response;
    });
}