Support + operator for adding items to the ImmutableCollection (#38)

* Support + operator for adding items to the ImmutableCollection.

src/Qowaiv.DomainModel/Collections/ImmutableCollection.cs

@@ -57,4 +57,11 @@ public ImmutableCollection Add(object? item)
     /// <inheritdoc />
     [Pure]
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+    /// <summary>Adds an item to the collection.</summary>
+    /// <remarks>
+    /// Syntactic sugar.
+    /// </remarks>
+    public static ImmutableCollection operator +(ImmutableCollection collection, object item)
+        => Guard.NotNull(collection, nameof(collection)).Add(item);
 }

src/Qowaiv.DomainModel/Collections/Then.cs

@@ -21,25 +21,22 @@ internal Then(bool done, ImmutableCollection item)
     /// <inheritdoc />
     public int Count => Items.Count;
 
-    /// <summary>Creates a new <see cref="ImmutableCollection"/> with the added items.</summary>
+    /// <summary>Creates a new <see cref="ImmutableCollection"/> with the added item(s).</summary>
+    /// <param name="item">
+    /// The item(s) to add.
+    /// </param>
     /// <remarks>
     /// Null, and null items are ignored.
     /// </remarks>
     [Pure]
-    public ImmutableCollection Add(params object?[] items) => Add<object[]>(items!);
+    public ImmutableCollection Add(object? item) => Items.Add(item!);
 
-    /// <summary>Creates a new <see cref="ImmutableCollection"/> with the added item(s).</summary>
-    /// <param name="item">
-    /// The item(s) to add.
-    /// </param>
-    /// <typeparam name="TItem">
-    /// The type of the item(s).
-    /// </typeparam>
+    /// <summary>Creates a new <see cref="ImmutableCollection"/> with the added items.</summary>
     /// <remarks>
     /// Null, and null items are ignored.
     /// </remarks>
     [Pure]
-    public ImmutableCollection Add<TItem>(TItem? item) where TItem : class => Items.Add(item);
+    public ImmutableCollection AddRange(params object?[]? items) => Add(items);
 
     /// <summary>Adds else-if condition.</summary>
     [Pure]

src/Qowaiv.DomainModel/EventDispatcher.cs

@@ -1,6 +1,4 @@
-using Qowaiv.DomainModel.Reflection;
-
-namespace Qowaiv.DomainModel;
+namespace Qowaiv.DomainModel;
 
 /// <summary>Factory for creating <see cref="ExpressionCompilingEventDispatcher{TDispatcher}"/>'s.</summary>
 public interface EventDispatcher

test/Qowaiv.DomainModel.UnitTests/Collections/Immutable_Collection_specs.cs

@@ -1,6 +1,4 @@
-using Qowaiv.DomainModel.UnitTests;
-
-namespace Collections.Immutable_Collection_specs;
+namespace Collections.Immutable_Collection_specs;
 
 internal static class Help
 {
@@ -79,6 +77,15 @@ public void Does_not_effect_shared_subs()
         first.Should().BeEquivalentTo(new[] { 1, 2, 4, 8, 16 });
         second.Should().BeEquivalentTo(new[] { 1, 2, 3, 4, 5 });
     }
+
+    [Test]
+    public void with_plus_operator()
+    {
+        var collection = ImmutableCollection.Empty;
+        collection += 3;
+        collection += new[] { 6, 9 };
+        collection.Should().BeEquivalentTo(new[] { 3, 6, 9 });
+    }
 }
 
 public class If_not_true

test/Qowaiv.DomainModel.UnitTests/Commands/CommandProcessor_specs.cs

@@ -1,6 +1,4 @@
-using Qowaiv.DomainModel.UnitTests;
-
-namespace Commands.CommandProcessor_specs;
+namespace Commands.CommandProcessor_specs;
 
 interface CommandHandler<TCommand> { Task<Result<string>> Handle(TCommand command); }
 interface CancelableCommandHandler<TCommand> { Task<Result<string>> Handle(TCommand command, CancellationToken token); }

test/Qowaiv.DomainModel.UnitTests/Event_sourced_aggregate_specs.cs

@@ -1,5 +1,4 @@
-using Qowaiv;
-using Qowaiv.DomainModel;
+using Qowaiv.DomainModel;
 using Qowaiv.DomainModel.UnitTests.Models;
 
 namespace Event_sourced_aggregate_specs

test/Qowaiv.DomainModel.UnitTests/TestTools/AggregateRootAssertTest.cs

@@ -1,10 +1,9 @@
 using Qowaiv.DomainModel.TestTools;
-using Qowaiv.DomainModel.UnitTests;
 using Qowaiv.Globalization;
 using TestEvents;
 
 namespace Qowaiv.DomainModel.UnitTests.TestTools
-{ 
+{
     public class AggregateRootAssertTest
     {
         [Test]