Fix account details model (#20)

* Change Singleton to Transient

* Update account details model
Change to WhenAll for fetching account details

* Remove uneccessary properties from bank models
Add log text that explains which field went wrong when serializing

* Refactor and enhance banking service and tests

- Update `BankClient_v2.cs` to adjust JSON properties and make `CreditDebitIndicator` nullable.
- Add `AccountExtensions.cs` with error logging method.
- Add `HasErrors` property to `AccountV2` in `BankResponse.cs`.
- Enhance `GetAccountDetailsV2` in `BankService.cs` for better error handling and logging.
- Update `Altinn.Dan.Plugin.Banking.Test.csproj` to target `net8.0`, add `FakeItEasy`, and reference `Altinn.Dan.Plugin.Banking`.
- Add `FakeableHttpMessageHandler.cs` for handling HTTP requests in tests and generating certificates.
- Add `BankServiceTests.cs` with comprehensive unit tests for `BankService`.
- Remove obsolete `UnitTest1.cs`.

* Fix failed tests

* Nullable enabled
Remove all required and add back some
Remove roles
Remove unused extension
Remove unused usings
Add tests

* Fix property references a bit after introducing nullable enable

* Fix balances

* Fix parallel request issues in GetAccounts method

Modified GetAccounts in BankService to fetch account details sequentially instead of in parallel to avoid 200 OK Internal Server Errors from Nordea. Added try-catch block to handle ApiException for each account individually, logging and adding default values for accounts with errors. Non-API exceptions are rethrown. Added comments explaining changes.

src/Altinn.Dan.Plugin.Banking/Services/BankService.cs

@@ -35,7 +35,6 @@ public BankService(ILoggerFactory loggerFactory, IMaskinportenService maskinport
             _settings = applicationSettings.Value;
         }
 
-
         public async Task<BankResponse> GetAccounts(string ssn, Dictionary<string, BankConfig> bankList, DateTimeOffset? fromDate, DateTimeOffset? toDate, Guid accountInfoRequestId, bool includeTransactions = true)
         {
             BankResponse bankResponse = new BankResponse { BankAccounts = [] };
@@ -115,17 +114,27 @@ private async Task<BankInfo> GetAccountDetailsV2(Bank_v2.Bank_v2 bankClient, Acc
                 return bankInfo;
             }
 
-            Task<AccountDetails>[] accountsDetailsTasks = accounts.Accounts1.Select(x => GetAccountById(bankClient, x, bank, accountInfoRequestId, fromDate, toDate)).ToArray();
-
-            var results = Task.WhenAll(accountsDetailsTasks);
-            try
+            /*
+             * TODO: Could this only be in Nordea test system?
+             * 
+             * Nordea has issues with parallell requests, so we need to fetch them one by one
+             * We have tried using the following:
+             * accountTasks.Add(Task.Run(async () => { ... })) but it does not work
+             * Task<AccountDetails>[] accountsDetailsTasks = accounts.Accounts1.Select(x => GetAccountById(bankClient, x, bank, accountInfoRequestId, fromDate, toDate)).ToArray();
+             * 
+             * Task.WhenAll(...)
+             * 
+             * Both of the functions will result in a 200 OK Internal Server Error from Nordea for some of the requests
+             * This only occurs when talking to Nordea
+            */
+            foreach (var account in accounts.Accounts1)
             {
-                AccountDetails[] accountsDetails = await results;
-                foreach (var accountDetails in accountsDetails)
+                try
                 {
-                    if (accountDetails?.Account == null) continue;
+                    var result = await GetAccountById(bankClient, account, bank, accountInfoRequestId, fromDate, toDate);
+                    if (result?.Account == null) continue;
 
-                    var balances = accountDetails.Account?.Balances;
+                    var balances = result.Account?.Balances;
 
                     var availableCredit = balances?.FirstOrDefault(b =>
                             b?.Type == BalanceType.AvailableBalance && b.CreditDebitIndicator == CreditOrDebit.Credit)
@@ -143,38 +152,29 @@ private async Task<BankInfo> GetAccountDetailsV2(Bank_v2.Bank_v2 bankClient, Acc
 
                     if (includeTransactions)
                     {
-                        transactions = await ListTransactionsForAccount(bankClient, accountDetails, bank, accountInfoRequestId, fromDate, toDate);
+                        transactions = await ListTransactionsForAccount(bankClient, result, bank, accountInfoRequestId, fromDate, toDate);
                     }
 
-                    var internalAccount = MapToInternalV2(accountDetails.Account!, transactions?.Transactions1, availableCredit - availableDebit, bookedCredit - bookedDebit);
+                    var internalAccount = MapToInternalV2(result.Account!, transactions?.Transactions1, availableCredit - availableDebit, bookedCredit - bookedDebit);
                     if (internalAccount.AccountDetail == null) continue;
 
                     bankInfo.Accounts.Add(internalAccount);
                 }
-            }
-            catch (Exception e)
-            {
-                if (e is ApiException k && k.StatusCode >= 400)
+                catch (Exception e)
                 {
-                    var successfulTasks = accountsDetailsTasks.Where(x => x.IsCompletedSuccessfully).ToArray();
-                    var successfulAccounts = await Task.WhenAll(successfulTasks);
-                    var faultedAccounts = accounts.Accounts1.Where(x => !successfulAccounts.Any(y => y.Account!.AccountReference == x.AccountReference)).ToList();
-
-                    foreach (var faultedAccount in faultedAccounts)
+                    if (e is ApiException k && k.StatusCode >= 400)
                     {
-                        faultedAccount.LogGetAccountByIdError(_logger, k, bank, accountInfoRequestId);
-                        bankInfo.Accounts.Add(faultedAccount.ToDefaultDto());
+                        account.LogGetAccountByIdError(_logger, k, bank, accountInfoRequestId);
+                        bankInfo.Accounts.Add(account.ToDefaultDto());
+                    }
+                    else
+                    {
+                        /* 
+                         * TODO:
+                         * Will rethrow if a non-API exception is thrown.
+                         */
+                        throw;
                     }
-                }
-                else
-                {
-                    /* 
-                     * TODO:
-                     * Will rethrow if a non-API exception is thrown.
-                     * A bank returns 200 OK Internal Server Error now, which is wrong.
-                     * It will then rethrow the exception
-                     */
-                    throw;
                 }
             }