Using Moq to test HttpClient RequestClientCredentialsTokenAsync

Question

I am trying to mock an Http Client that uses the IdentityModel extension to request a client credentials token.

var tokenResponse = await _httpClient.RequestClientCredentialsTokenAsync(requestContent);

I started doing the setup with:

var httpClient = new Mock<HttpClient>();


var httpResponseMessage = new HttpResponseMessage(HttpStatusCode.OK)
{
    Content = JsonContent.Create(new
    {
        access_token = "token",
        expires_in = 5000
    })
};

var tokenResponse = ProtocolResponse.FromHttpResponseAsync<TokenResponse>(httpResponseMessage);

httpClient.Setup(x => x.RequestClientCredentialsTokenAsync(It.IsAny<ClientCredentialsTokenRequest>(), It.IsAny<CancellationToken>())).Returns(tokenResponse);

But i end up with:

System.NotSupportedException : Unsupported expression: x => x.RequestClientCredentialsTokenAsync(It.IsAny(), It.IsAny()) Extension methods (here: HttpClientTokenRequestExtensions.RequestClientCredentialsTokenAsync) may not be used in setup / verification expressions.

How can i mock the RequestClientCredentialsTokenAsync extension?

Answer 1

Looking at the internals of RequestClientCredentialsTokenAsync we can see that the base request it is using is SendAsync, so we need to mock SendAsync.

Extension call:

response = await client.SendAsync(request, cancellationToken).ConfigureAwait();

Final Setup:

var httpClient = new Mock<HttpClient>();

var httpResponseMessage = new HttpResponseMessage(HttpStatusCode.OK)
{
    Content = JsonContent.Create(new
    {
        access_token = "token",
        expires_in = 5000
    })
};

httpClient.Setup(x => x.SendAsync(It.IsAny<HttpRequestMessage>(), It.IsAny<CancellationToken>())).Returns(Task.FromResult(httpResponseMessage));

Result: