fix(store-and-forward): resolve StoreAndForward-003, re-triage 002 — fix retry-count off-by-one

tests/ScadaLink.StoreAndForward.Tests/StoreAndForwardServiceTests.cs

@@ -86,7 +86,9 @@ public class StoreAndForwardServiceTests : IAsyncLifetime, IDisposable
         var msg = await _storage.GetMessageByIdAsync(result.MessageId);
         Assert.NotNull(msg);
         Assert.Equal(StoreAndForwardMessageStatus.Pending, msg!.Status);
-        Assert.Equal(1, msg.RetryCount);
+        // StoreAndForward-003: RetryCount counts sweep retries only; the immediate
+        // attempt is attempt 0, so a freshly buffered message has RetryCount 0.
+        Assert.Equal(0, msg.RetryCount);
     }
 
     [Fact]
@@ -134,6 +136,12 @@ public class StoreAndForwardServiceTests : IAsyncLifetime, IDisposable
             StoreAndForwardCategory.ExternalSystem, "api", """{}""",
             maxRetries: 2);
 
+        // StoreAndForward-003: MaxRetries bounds sweep retries (not the immediate
+        // attempt), so a message with MaxRetries=2 needs two retry sweeps to park.
+        await _service.RetryPendingMessagesAsync();
+        var afterFirst = await _storage.GetMessageByIdAsync(result.MessageId);
+        Assert.Equal(StoreAndForwardMessageStatus.Pending, afterFirst!.Status);
+
         await _service.RetryPendingMessagesAsync();
 
         var msg = await _storage.GetMessageByIdAsync(result.MessageId);
@@ -141,6 +149,34 @@ public class StoreAndForwardServiceTests : IAsyncLifetime, IDisposable
         Assert.Equal(StoreAndForwardMessageStatus.Parked, msg!.Status);
     }
 
+    // ── StoreAndForward-003: retry-count accounting ──
+
+    [Fact]
+    public async Task RetryPendingMessagesAsync_MaxRetriesOne_PerformsExactlyOneRetryBeforeParking()
+    {
+        // The immediate attempt is attempt 0; MaxRetries=1 must allow exactly one
+        // retry sweep before parking. The pre-fix off-by-one parked with zero retries.
+        var attempts = 0;
+        _service.RegisterDeliveryHandler(StoreAndForwardCategory.ExternalSystem,
+            _ => { Interlocked.Increment(ref attempts); throw new HttpRequestException("always fails"); });
+
+        var result = await _service.EnqueueAsync(
+            StoreAndForwardCategory.ExternalSystem, "api", """{}""",
+            maxRetries: 1);
+
+        // After the immediate failed attempt the message is buffered, not parked.
+        var buffered = await _storage.GetMessageByIdAsync(result.MessageId);
+        Assert.Equal(StoreAndForwardMessageStatus.Pending, buffered!.Status);
+        Assert.Equal(1, attempts); // only the immediate attempt so far
+
+        await _service.RetryPendingMessagesAsync();
+
+        var msg = await _storage.GetMessageByIdAsync(result.MessageId);
+        Assert.Equal(StoreAndForwardMessageStatus.Parked, msg!.Status);
+        Assert.Equal(2, attempts);      // immediate attempt + exactly one retry
+        Assert.Equal(1, msg.RetryCount); // one sweep retry recorded
+    }
+
     [Fact]
     public async Task RetryPendingMessagesAsync_PermanentFailureOnRetry_ParksMessage()
     {
@@ -332,6 +368,8 @@ public class StoreAndForwardServiceTests : IAsyncLifetime, IDisposable
         var msg = await _storage.GetMessageByIdAsync(result.MessageId);
         Assert.NotNull(msg);
         Assert.Equal(StoreAndForwardMessageStatus.Pending, msg!.Status);
-        Assert.Equal(1, msg.RetryCount);  // counts as the caller's first attempt
+        // StoreAndForward-003: the caller's own attempt is attempt 0; RetryCount
+        // counts only sweep retries, so a freshly buffered message has RetryCount 0.
+        Assert.Equal(0, msg.RetryCount);
     }
 }