internals: validate arguments with the Argument helper

src/Ramstack.HtmxToolkit/Argument.cs

@@ -0,0 +1,73 @@
+// ReSharper disable ParameterOnlyUsedForPreconditionCheck.Local
+
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
+
+namespace Ramstack.HtmxToolkit;
+
+/// <summary>
+/// Provides helper methods to validate arguments and throw exceptions if the arguments do not meet specified conditions.
+/// </summary>
+internal static class Argument
+{
+    /// <summary>
+    /// Throws an <see cref="ArgumentNullException"/> if the specified object is <see langword="null"/>.
+    /// </summary>
+    /// <param name="value">The object to check.</param>
+    /// <param name="paramName">The name of the parameter being checked. Automatically supplied by the compiler.</param>
+    public static void ThrowIfNull([NotNull] object? value, [CallerArgumentExpression(nameof(value))] string? paramName = null)
+    {
+        if (value is null)
+            Error_ArgumentNull(paramName);
+    }
+
+    /// <summary>
+    /// Throws an <see cref="ArgumentNullException"/> if the specified string is <see langword="null"/>,
+    /// or an <see cref="ArgumentException"/> if it is empty.
+    /// </summary>
+    /// <param name="value">The string to check.</param>
+    /// <param name="paramName">The name of the parameter being checked. Automatically supplied by the compiler.</param>
+    public static void ThrowIfNullOrEmpty([NotNull] string? value, [CallerArgumentExpression(nameof(value))] string? paramName = null)
+    {
+        if (string.IsNullOrEmpty(value))
+            Error_ArgumentNullOrEmpty(value, paramName);
+    }
+
+    /// <summary>
+    /// Throws an <see cref="ArgumentNullException"/> if the specified string is <see langword="null"/>,
+    /// or an <see cref="ArgumentException"/> if it is empty or consists only of white-space characters.
+    /// </summary>
+    /// <param name="value">The string to check.</param>
+    /// <param name="paramName">The name of the parameter being checked. Automatically supplied by the compiler.</param>
+    public static void ThrowIfNullOrWhiteSpace([NotNull] string? value, [CallerArgumentExpression(nameof(value))] string? paramName = null)
+    {
+        if (string.IsNullOrWhiteSpace(value))
+            Error_ArgumentNullOrWhiteSpace(value, paramName);
+    }
+
+    [DoesNotReturn]
+    private static void Error_ArgumentNull(string? paramName) =>
+        throw new ArgumentNullException(paramName);
+
+    [DoesNotReturn]
+    private static void Error_ArgumentNullOrEmpty(string? value, string? paramName)
+    {
+        if (value is null)
+            throw new ArgumentNullException(paramName);
+
+        throw new ArgumentException(
+            "Argument should not be empty.",
+            paramName);
+    }
+
+    [DoesNotReturn]
+    private static void Error_ArgumentNullOrWhiteSpace(string? value, string? paramName)
+    {
+        if (value is null)
+            throw new ArgumentNullException(paramName);
+
+        throw new ArgumentException(
+            "Argument should not be empty or whitespace.",
+            paramName);
+    }
+}

src/Ramstack.HtmxToolkit/Collections/SmallDictionary.cs

@@ -77,7 +77,7 @@ public TValue this[TKey key]
     /// <param name="comparer">The comparer to use when comparing keys.</param>
     public SmallDictionary(IComparer<TKey> comparer)
     {
-        ArgumentNullException.ThrowIfNull(comparer);
+        Argument.ThrowIfNull(comparer);
         _comparer = comparer;
     }
 
@@ -90,7 +90,7 @@ public SmallDictionary(IComparer<TKey> comparer)
     /// <param name="comparer">The comparer to use when comparing keys.</param>
     public SmallDictionary(IEnumerable<KeyValuePair<TKey, TValue>> collection, IComparer<TKey> comparer) : this(comparer)
     {
-        ArgumentNullException.ThrowIfNull(collection);
+        Argument.ThrowIfNull(collection);
 
         if (collection is Dictionary<TKey, TValue> dictionary)
         {

src/Ramstack.HtmxToolkit/HtmxResponse.cs

@@ -95,8 +95,7 @@ static HtmxResponse LocationImpl(HtmxResponse response, string path, HtmxLocatio
     /// </remarks>
     public HtmxResponse PushUrl(string url)
     {
-        if (string.IsNullOrEmpty(url))
-            throw new ArgumentException("URL cannot be null or empty.", nameof(url));
+        Argument.ThrowIfNullOrEmpty(url);
 
         return SetHistoryHeader(this, HtmxResponseHeaderNames.PushUrl, url, HtmxResponseHeaderNames.ReplaceUrl);
     }
@@ -127,8 +126,7 @@ public HtmxResponse PushUrl(string url)
     /// </remarks>
     public HtmxResponse ReplaceUrl(string url)
     {
-        if (string.IsNullOrEmpty(url))
-            throw new ArgumentException("URL cannot be null or empty.", nameof(url));
+        Argument.ThrowIfNullOrEmpty(url);
 
         return SetHistoryHeader(this, HtmxResponseHeaderNames.ReplaceUrl, url, HtmxResponseHeaderNames.PushUrl);
     }
@@ -344,7 +342,7 @@ private static HtmxResponse TriggerEventCore<T>(HtmxResponse response, string ev
 
     private static string SerializeEventDetail<T>(T detail, JsonTypeInfo<T> jsonTypeInfo)
     {
-        ArgumentNullException.ThrowIfNull(jsonTypeInfo);
+        Argument.ThrowIfNull(jsonTypeInfo);
 
         var buffer = new ArrayBufferWriter<byte>();
         using (var writer = new Utf8JsonWriter(buffer, new JsonWriterOptions { Encoder = JsonOptions.Encoder, SkipValidation = true }))

src/Ramstack.HtmxToolkit/Internal/PendingEvents.cs

@@ -49,11 +49,8 @@ private PendingEvents(HttpResponse response) =>
     /// <param name="detailJson">The event detail as JSON.</param>
     public void AddEvent(HtmxTriggerTiming timing, string eventName, string detailJson)
     {
-        if (string.IsNullOrWhiteSpace(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));
+        Argument.ThrowIfNullOrWhiteSpace(eventName);
+        Argument.ThrowIfNullOrWhiteSpace(detailJson);
 
         if (eventName == ProxyEventName)
             throw new ArgumentException(

tests/Ramstack.HtmxToolkit.Tests/HtmxResponseTests.cs

@@ -353,7 +353,7 @@ public void ReplaceUrl_NullOrEmpty_ThrowsArgumentException(string? url)
     {
         var context = TestHelper.CreateHtmxRequestContext();
 
-        var exception = Assert.Throws<ArgumentException>(() =>
+        var exception = Assert.Catch<ArgumentException>(() =>
             context.Response.Htmx(r => r.ReplaceUrl(url!)));
 
         Assert.That(exception?.ParamName, Is.EqualTo("url"));

tests/Ramstack.HtmxToolkit.Tests/Internal/PendingEventsTests.cs

@@ -357,7 +357,7 @@ public void AddEvent_NullOrWhitespaceDetail_ThrowsArgumentException(string? deta
         var context = TestHelper.CreateHttpContext();
         var pending = PendingEvents.GetOrCreate(context.Response);
 
-        var exception = Assert.Throws<ArgumentException>(() =>
+        var exception = Assert.Catch<ArgumentException>(() =>
             pending.AddEvent(HtmxTriggerTiming.Receive, "e", detail!));
 
         Assert.That(exception?.ParamName, Is.EqualTo("detailJson"));
@@ -371,7 +371,7 @@ public void AddEvent_NullOrWhitespaceEventName_ThrowsArgumentException(string? e
         var context = TestHelper.CreateHttpContext();
         var pending = PendingEvents.GetOrCreate(context.Response);
 
-        var exception = Assert.Throws<ArgumentException>(() =>
+        var exception = Assert.Catch<ArgumentException>(() =>
             pending.AddEvent(HtmxTriggerTiming.Receive, eventName!, "1"));
 
         Assert.That(exception?.ParamName, Is.EqualTo("eventName"));