Fix possible null reference exception on expired access token use

src/RobinTTY.NordigenApiClient.Tests/Endpoints/TokenEndpointTests.cs

@@ -1,5 +1,6 @@
 using System.Net;
 using RobinTTY.NordigenApiClient.Models;
+using RobinTTY.NordigenApiClient.Models.Jwt;
 
 namespace RobinTTY.NordigenApiClient.Tests.Endpoints;
 
@@ -45,4 +46,22 @@ public async Task GetTokenWithInvalidCredentials()
         Assert.That(response.StatusCode, Is.EqualTo(HttpStatusCode.Unauthorized));
         Assert.That(response.Error, Is.Not.Null);
     }
+
+    /// <summary>
+    /// Tests using the API with an expired access token.
+    /// Requires secrets.txt to contain expired access token / valid refresh token pair.
+    /// </summary>
+    /// <returns></returns>
+    [Test]
+    public async Task ReuseExpiredToken()
+    {
+        var secrets = await File.ReadAllLinesAsync("secrets.txt");
+        var httpClient = new HttpClient();
+        var credentials = new NordigenClientCredentials(secrets[0], secrets[1]);
+        var tokenPair = new JsonWebTokenPair(secrets[6], secrets[7]);
+        var apiClient = new NordigenClient(httpClient, credentials, tokenPair);
+
+        var result = await apiClient.RequisitionsEndpoint.GetRequisitions(10, 0);
+        TestExtensions.AssertNordigenApiResponseIsSuccessful(result, HttpStatusCode.OK);
+    }
 }

src/RobinTTY.NordigenApiClient.Tests/TestExtensions.cs

@@ -36,7 +36,7 @@ internal static NordigenClient GetConfiguredClient(bool useExistingJwt = true)
         var httpClient = new HttpClient();
         var secrets = File.ReadAllLines("secrets.txt");
         var credentials = new NordigenClientCredentials(secrets[0], secrets[1]);
-        var tokenPair = new JsonWebTokenPair(secrets[2], secrets[3]);
+        var tokenPair = new JsonWebTokenPair(secrets[3], secrets[4]);
         return useExistingJwt ? new NordigenClient(httpClient, credentials, tokenPair) : new NordigenClient(httpClient, credentials);
     }
 }

src/RobinTTY.NordigenApiClient/NordigenClient.cs

@@ -85,8 +85,16 @@ internal async Task<NordigenApiResponse<TResponse, TError>> MakeRequest<TRespons
         ) where TResponse : class where TError : class
     {
         var requestUri = query != null ? UriQueryBuilder.BuildUriWithQueryString(uri, query) : uri;
-        JsonWebTokenPair = useAuthentication ? await TryGetValidTokenPair(cancellationToken) : null;
-        var client = useAuthentication ? _httpClient.UseNordigenAuthenticationHeader(JsonWebTokenPair) : _httpClient;
+        HttpClient client;
+        if (useAuthentication)
+        {
+            JsonWebTokenPair = await TryGetValidTokenPair(cancellationToken);
+            client = _httpClient.UseNordigenAuthenticationHeader(JsonWebTokenPair);
+        }
+        else
+        {
+            client = _httpClient;
+        }
 
         HttpResponseMessage ? response;
         if (method == HttpMethod.Get)

src/RobinTTY.NordigenApiClient/RobinTTY.NordigenApiClient.csproj

@@ -14,7 +14,7 @@
     <PackageTags>Nordigen; API; client</PackageTags>
     <PackageReleaseNotes>$([System.IO.File]::ReadAllText("$(MSBuildProjectDirectory)/release-notes.txt"))</PackageReleaseNotes>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
-    <Version>4.0.1</Version>
+    <Version>4.0.2</Version>
   </PropertyGroup>
 
   <ItemGroup>

src/RobinTTY.NordigenApiClient/release-notes.txt

@@ -1 +1 @@
-Fixes possible null reference exception on event invocation.
+Fixes possible null reference exception on expired access token use.