Add IRobustRandom extension to get a random value from a data set (#3260)

* Add extension to pick a random element from a dataset

* Add tests

Content.Shared/Utility/SharedRandomExtensions.cs

@@ -0,0 +1,13 @@
+using Content.Shared.Prototypes;
+using Robust.Shared.Random;
+
+namespace Content.Shared.Utility
+{
+    public static class SharedRandomExtensions
+    {
+        public static string Pick(this IRobustRandom random, DatasetPrototype prototype)
+        {
+            return random.Pick(prototype.Values);
+        }
+    }
+}

Content.Tests/Shared/Utility/RandomExtensionsTests.cs

@@ -0,0 +1,38 @@
+using System.IO;
+using System.Threading.Tasks;
+using Content.Shared.Prototypes;
+using Content.Shared.Utility;
+using NUnit.Framework;
+using Robust.Shared.IoC;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Random;
+
+namespace Content.Tests.Shared.Utility
+{
+    [TestFixture]
+    [TestOf(typeof(SharedRandomExtensions))]
+    public class RandomExtensionsTests : ContentUnitTest
+    {
+        private const string TestDatasetId = "TestDataset";
+
+        private static readonly string Prototypes = $@"
+- type: dataset
+  id: {TestDatasetId}
+  values:
+  - A";
+
+        [Test]
+        public void RandomDataSetValueTest()
+        {
+            var prototypeManager = IoCManager.Resolve<IPrototypeManager>();
+
+            prototypeManager.LoadFromStream(new StringReader(Prototypes));
+
+            var dataSet = prototypeManager.Index<DatasetPrototype>(TestDatasetId);
+            var random = IoCManager.Resolve<IRobustRandom>();
+            var id = random.Pick(dataSet);
+
+            Assert.NotNull(id);
+        }
+    }
+}