Allow solutions to store extra reagent data (#19323)

Content.IntegrationTests/Tests/Chemistry/ReagentDataTest.cs

@@ -0,0 +1,30 @@
+using Content.IntegrationTests.Tests.Interaction;
+using Content.Shared.Chemistry.Reagent;
+using Robust.Shared.Reflection;
+using Robust.Shared.Serialization;
+using Robust.Shared.Utility;
+
+namespace Content.IntegrationTests.Tests.Chemistry;
+
+[TestFixture]
+[TestOf(typeof(ReagentData))]
+public sealed class ReagentDataTest : InteractionTest
+{
+    [Test]
+    public async Task ReagentDataIsSerializable()
+    {
+        await using var pair = await PoolManager.GetServerClient();
+        var reflection = pair.Server.ResolveDependency<IReflectionManager>();
+
+        Assert.Multiple(() =>
+        {
+            foreach (var instance in reflection.GetAllChildren(typeof(ReagentData)))
+            {
+                Assert.That(instance.HasCustomAttribute<NetSerializableAttribute>(), $"{instance} must have the NetSerializable attribute.");
+                Assert.That(instance.HasCustomAttribute<SerializableAttribute>(), $"{instance} must have the serializable attribute.");
+            }
+        });
+
+        await pair.CleanReturnAsync();
+    }
+}