http: reject null or whitespace trigger event details

src/Ramstack.HtmxToolkit/HtmxResponse.cs

@@ -210,7 +210,7 @@ public HtmxResponse Reselect(string value) =>
     /// See <see href="https://github.com/bigskysoftware/htmx/pull/3900">PR #3900</see>.
     /// </remarks>
     public HtmxResponse TriggerEvent(string eventName, HtmxTriggerTiming trigger = HtmxTriggerTiming.Receive) =>
-        QueueEvent(this, eventName, "{}", trigger);
+        AddToPendingEvent(this, eventName, "{}", trigger);
 
     /// <summary>
     /// Adds a client-side event and its detail to the response header selected by
@@ -274,10 +274,10 @@ private static HtmxResponse SetHeader(HtmxResponse response, string key, string
     [RequiresDynamicCode("Event details are serialized using reflection.")]
     [RequiresUnreferencedCode("Event details are serialized using reflection.")]
     private static HtmxResponse TriggerEventCore(HtmxResponse response, string eventName, object detail, HtmxTriggerTiming timing) =>
-        QueueEvent(response, eventName, JsonSerializer.Serialize(detail, JsonOptions.CamelCase), timing);
+        AddToPendingEvent(response, eventName, JsonSerializer.Serialize(detail, JsonOptions.CamelCase), timing);
 
     private static HtmxResponse TriggerEventCore<T>(HtmxResponse response, string eventName, T detail, JsonTypeInfo<T> jsonTypeInfo, HtmxTriggerTiming timing) =>
-        QueueEvent(response, eventName, SerializeEventDetail(detail, jsonTypeInfo), timing);
+        AddToPendingEvent(response, eventName, SerializeEventDetail(detail, jsonTypeInfo), timing);
 
     private static string SerializeEventDetail<T>(T detail, JsonTypeInfo<T> jsonTypeInfo)
     {
@@ -290,9 +290,9 @@ private static string SerializeEventDetail<T>(T detail, JsonTypeInfo<T> jsonType
         return Encoding.UTF8.GetString(buffer.WrittenSpan);
     }
 
-    private static HtmxResponse QueueEvent(HtmxResponse response, string eventName, string detail, HtmxTriggerTiming timing)
+    private static HtmxResponse AddToPendingEvent(HtmxResponse response, string eventName, string detailJson, HtmxTriggerTiming timing)
     {
-        PendingEvents.GetOrCreate(response._response).AddEvent(timing, eventName, detail);
+        PendingEvents.GetOrCreate(response._response).AddEvent(timing, eventName, detailJson);
         return response;
     }
 

src/Ramstack.HtmxToolkit/PendingEvents.cs

@@ -41,22 +41,20 @@ private PendingEvents(HttpResponse response) =>
     /// </summary>
     /// <param name="timing">The time at which to trigger the events.</param>
     /// <param name="eventName">The event name.</param>
-    /// <param name="detail">The event detail.</param>
-    public void AddEvent(HtmxTriggerTiming timing, string eventName, string? detail)
+    /// <param name="detailJson">The event detail as JSON.</param>
+    public void AddEvent(HtmxTriggerTiming timing, string eventName, string detailJson)
     {
-        ArgumentNullException.ThrowIfNull(eventName);
-
         if (string.IsNullOrWhiteSpace(eventName))
-            throw new ArgumentException("Event name cannot be empty.", nameof(eventName));
+            throw new ArgumentException("Event name cannot be null or whitespace.", nameof(eventName));
+
+        if (string.IsNullOrWhiteSpace(detailJson))
+            throw new ArgumentException("Event detail JSON cannot be null or whitespace.", nameof(detailJson));
 
         if (eventName == ProxyEventName)
             throw new ArgumentException(
                 $"The event name '{ProxyEventName}' is reserved.",
                 nameof(eventName));
 
-        if (string.IsNullOrWhiteSpace(detail))
-            detail = "{}";
-
         timing = NormalizeTiming(timing);
 
         var current = timing switch
@@ -66,7 +64,7 @@ public void AddEvent(HtmxTriggerTiming timing, string eventName, string? detail)
             _ => _afterSettle ??= new SmallDictionary<string, object>(StringComparer.Ordinal)
         };
 
-        if (!current.TryAdd(eventName, detail))
+        if (!current.TryAdd(eventName, detailJson))
         {
             if (!current.TryGetValue(ProxyEventName, out var value)
                 || value is not List<KeyValuePair<string, string>> collection)
@@ -75,7 +73,7 @@ public void AddEvent(HtmxTriggerTiming timing, string eventName, string? detail)
                 current[ProxyEventName] = collection;
             }
 
-            collection.Add(new KeyValuePair<string, string>(eventName, detail));
+            collection.Add(new KeyValuePair<string, string>(eventName, detailJson));
         }
     }
 

tests/Ramstack.HtmxToolkit.Tests/PendingEventsTests.cs

@@ -204,37 +204,27 @@ public void Flush_SerializesNullEventDetail_AsNull()
     [TestCase(null)]
     [TestCase("")]
     [TestCase("   ")]
-    public void AddEvent_NullOrWhitespaceDetail_NormalizesToEmptyObject(string? detail)
+    public void AddEvent_NullOrWhitespaceDetail_ThrowsArgumentException(string? detail)
     {
         var context = TestHelper.CreateHttpContext();
         var pending = PendingEvents.GetOrCreate(context.Response);
 
-        pending.AddEvent(HtmxTriggerTiming.Receive, "e", detail);
-        pending.Flush();
-
-        var header = context.Response.Headers[HtmxResponseHeaderNames.Trigger].ToString();
-        Assert.That(header, Is.EqualTo("{\"e\":{}}"));
-    }
-
-    [Test]
-    public void AddEvent_NullEventName_ThrowsArgumentNullException()
-    {
-        var context = TestHelper.CreateHttpContext();
-        var pending = PendingEvents.GetOrCreate(context.Response);
+        var exception = Assert.Throws<ArgumentException>(() =>
+            pending.AddEvent(HtmxTriggerTiming.Receive, "e", detail!));
 
-        Assert.Throws<ArgumentNullException>(() =>
-            pending.AddEvent(HtmxTriggerTiming.Receive, null!, "1"));
+        Assert.That(exception?.ParamName, Is.EqualTo("detailJson"));
     }
 
+    [TestCase(null)]
     [TestCase("")]
     [TestCase("   ")]
-    public void AddEvent_EmptyOrWhitespaceEventName_ThrowsArgumentException(string eventName)
+    public void AddEvent_NullOrWhitespaceEventName_ThrowsArgumentException(string? eventName)
     {
         var context = TestHelper.CreateHttpContext();
         var pending = PendingEvents.GetOrCreate(context.Response);
 
         var exception = Assert.Throws<ArgumentException>(() =>
-            pending.AddEvent(HtmxTriggerTiming.Receive, eventName, "1"));
+            pending.AddEvent(HtmxTriggerTiming.Receive, eventName!, "1"));
 
         Assert.That(exception?.ParamName, Is.EqualTo("eventName"));
     }