private async Task ShouldRefreshToken(Func <HttpRequestMessage, CancellationToken, Task <HttpResponseMessage> > handlerFunc)
        {
            // Arrange
            var tokenStore      = A.Fake <ITokenStore>();
            var tokenCredential = new TokenCredential {
                AccessToken = "access_token", RefreshToken = "refresh_token"
            };

            A.CallTo(() => tokenStore.GetToken("tokenid")).ReturnsLazily(() => tokenCredential);
            A.CallTo(() => tokenStore.StoreToken("tokenid", A <TokenResponse> ._)).Invokes(x => { tokenCredential.AccessToken = x.Arguments.Get <TokenResponse>("response").AccessToken; });
            var timesSendAsync = 0;
            var oAuth2Client   = new TestingOAuth2Client("new_access_token", "new_refresh_token");
            var handler        = new OAuthHttpClientHandler("tokenid", tokenStore, oAuth2Client)
            {
                InnerHandler = new TestHandler((r, c) => { timesSendAsync++; return(handlerFunc.Invoke(r, c)); })
            };
            var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "http://test/");
            var client             = new HttpClient(handler);

            // Act
            await client.SendAsync(httpRequestMessage);

            // Assert
            A.CallTo(() => tokenStore.StoreToken("tokenid", A <TokenResponse> .That.Matches(x => x.AccessToken == "new_access_token"))).MustHaveHappened(Repeated.Exactly.Once);
            httpRequestMessage.Headers.Authorization.Should().Be(new AuthenticationHeaderValue("Bearer", "new_access_token"));
            timesSendAsync.Should().Be(2);
        }
        private async Task ShouldRefreshToken(Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> handlerFunc)
        {
            // Arrange
            var tokenStore = A.Fake<ITokenStore>();
            var tokenCredential = new TokenCredential { AccessToken = "access_token", RefreshToken = "refresh_token" };
            A.CallTo(() => tokenStore.GetToken("tokenid")).ReturnsLazily(() => tokenCredential);
            A.CallTo(() => tokenStore.StoreToken("tokenid", A<TokenResponse>._)).Invokes(x => { tokenCredential.AccessToken = x.Arguments.Get<TokenResponse>("response").AccessToken; });
            var timesSendAsync = 0;
            var oAuth2Client = new TestingOAuth2Client("new_access_token", "new_refresh_token");
            var handler = new OAuthHttpClientHandler("tokenid", tokenStore, oAuth2Client) { InnerHandler = new TestHandler((r, c) => { timesSendAsync++; return handlerFunc.Invoke(r, c); }) };
            var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "http://test/");
            var client = new HttpClient(handler);

            // Act
            await client.SendAsync(httpRequestMessage);

            // Assert 
            A.CallTo(() => tokenStore.StoreToken("tokenid", A<TokenResponse>.That.Matches(x => x.AccessToken == "new_access_token"))).MustHaveHappened(Repeated.Exactly.Once);
            httpRequestMessage.Headers.Authorization.Should().Be(new AuthenticationHeaderValue("Bearer", "new_access_token"));
            timesSendAsync.Should().Be(2);
        }
        private void ShouldNotRefreshToken(Func <HttpRequestMessage, CancellationToken, Task <HttpResponseMessage> > handlerFunc)
        {
            // Arrange
            var tokenStore      = A.Fake <ITokenStore>();
            var tokenCredential = new TokenCredential {
                AccessToken = "access_token", RefreshToken = "refresh_token"
            };

            A.CallTo(() => tokenStore.GetToken("tokenid")).ReturnsLazily(() => tokenCredential);
            A.CallTo(() => tokenStore.StoreToken("tokenid", A <TokenResponse> ._)).Invokes(x => { tokenCredential.AccessToken = x.Arguments.Get <TokenResponse>("response").AccessToken; });
            var oAuth2Client = new TestingOAuth2Client("error");
            var handler      = new OAuthHttpClientHandler("tokenid", tokenStore, oAuth2Client)
            {
                InnerHandler = new TestHandler(handlerFunc)
            };
            var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "http://test/");
            var client             = new HttpClient(handler);

            // Act/Assert
            Assert.ThrowsAsync <InvalidRefreshTokenException>(() => client.SendAsync(httpRequestMessage));
        }
        private void ShouldNotRefreshToken(Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> handlerFunc)
        {
            // Arrange
            var tokenStore = A.Fake<ITokenStore>();
            var tokenCredential = new TokenCredential { AccessToken = "access_token", RefreshToken = "refresh_token" };
            A.CallTo(() => tokenStore.GetToken("tokenid")).ReturnsLazily(() => tokenCredential);
            A.CallTo(() => tokenStore.StoreToken("tokenid", A<TokenResponse>._)).Invokes(x => { tokenCredential.AccessToken = x.Arguments.Get<TokenResponse>("response").AccessToken; });
            var oAuth2Client = new TestingOAuth2Client("error");
            var handler = new OAuthHttpClientHandler("tokenid", tokenStore, oAuth2Client) { InnerHandler = new TestHandler(handlerFunc) };
            var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "http://test/");
            var client = new HttpClient(handler);

            // Act/Assert
            Assert.ThrowsAsync<InvalidRefreshTokenException>(() => client.SendAsync(httpRequestMessage));
        }