use _keyBytes to check if key has been initialized

Author: terencefan

src/Microsoft.Azure.SignalR.Common/Auth/MicrosoftEntra/MicrosoftEntraAccessKey.cs

@@ -60,7 +60,7 @@ private set
         {
             if (value)
             {
-                LastException = new Exception("The access key has expired.");
+                LastException = null;
             }
             _updateAt = DateTime.UtcNow;
             _isAuthorized = value;
@@ -73,7 +73,7 @@ private set
 
     public byte[] KeyBytes => _keyBytes ?? throw new ArgumentNullException(nameof(KeyBytes));
 
-    internal Exception LastException { get; private set; } = new Exception("The access key has not been initialized.");
+    internal Exception? LastException { get; private set; }
 
     internal string GetAccessKeyUrl { get; }
 
@@ -135,7 +135,7 @@ public async Task<string> GenerateAccessTokenAsync(string audience,
         }
         return Available
             ? AuthUtility.GenerateAccessToken(KeyBytes, Kid, audience, claims, lifetime, algorithm)
-            : throw new AzureSignalRAccessTokenNotAuthorizedException(TokenCredential, GetExceptionMessage(LastException), LastException);
+            : throw new AzureSignalRAccessTokenNotAuthorizedException(TokenCredential, GetExceptionMessage(LastException, _keyBytes != null), LastException);
     }
 
     internal void UpdateAccessKey(string kid, string keyStr)
@@ -199,12 +199,12 @@ private async Task UpdateAccessKeyInternalAsync(TaskCompletionSource<bool> tcs)
         tcs.TrySetResult(false);
     }
 
-    private static string GetExceptionMessage(Exception exception)
+    private static string GetExceptionMessage(Exception? exception, bool initialized)
     {
         return exception switch
         {
             AzureSignalRUnauthorizedException => AzureSignalRUnauthorizedException.ErrorMessageMicrosoftEntra,
-            _ => exception.Message,
+            _ => exception?.Message ?? (initialized ? "Access key has expired" : "The access key has not initialized"),
         };
     }
 

test/Microsoft.Azure.SignalR.Common.Tests/Auth/MicrosoftEntraAccessKeyTests.cs

@@ -133,7 +133,7 @@ public async Task TestUpdateAccessKeyFailedThrowsNotAuthorizedException(AzureSig
 
         var (kid, accessKey) = ("foo", DefaultSigningKey);
         key.UpdateAccessKey(kid, accessKey);
-        Assert.Contains("has expired", key.LastException.Message);
+        Assert.Null(key.LastException);
     }
 
     [Theory]