Add inventory helpers and an integration test for it (#1841)

Content.Server/Utility/InventoryHelpers.cs

@@ -0,0 +1,49 @@
+using Content.Server.GameObjects.Components.GUI;
+using Content.Server.GameObjects.Components.Items.Storage;
+using Content.Shared.GameObjects.Components.Inventory;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Prototypes;
+using static Content.Shared.GameObjects.Components.Inventory.EquipmentSlotDefines;
+
+namespace Content.Server.Utility
+{
+    public static class InventoryHelpers
+    {
+        public static bool SpawnItemInSlot(this InventoryComponent inventory, Slots slot, string prototype, bool mobCheck = false)
+        {
+            var entityManager = inventory.Owner.EntityManager;
+            var protoManager = IoCManager.Resolve<IPrototypeManager>();
+
+            // Let's do nothing if the owner of the inventory has been deleted.
+            if (inventory.Owner.Deleted)
+                return false;
+
+            // If we don't have that slot or there's already an item there, we do nothing.
+            if (!inventory.HasSlot(slot) || inventory.TryGetSlotItem(slot, out ItemComponent _))
+                return false;
+
+            // If the prototype in question doesn't exist, we do nothing.
+            if (!protoManager.HasIndex<EntityPrototype>(prototype))
+                return false;
+
+            // Let's spawn this in nullspace first...
+            var item = entityManager.SpawnEntity(prototype, MapCoordinates.Nullspace);
+
+            // Helper method that deletes the item and returns false.
+            bool DeleteItem()
+            {
+                item.Delete();
+                return false;
+            }
+
+            // If this doesn't have an item component, then we can't do anything with it.
+            if (!item.TryGetComponent(out ItemComponent itemComp))
+                return DeleteItem();
+
+            // We finally try to equip the item, otherwise we delete it.
+            return inventory.Equip(slot, itemComp, mobCheck) || DeleteItem();
+        }
+    }
+}