Stat checks: check command with stat roll outcomes and its schema

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/StatCheckTests.cs

@@ -0,0 +1,37 @@
+namespace Cthangover.Mods.StatChecks.Tests
+{
+    using System;
+    using Cthangover.Core.Mods.Testing;
+
+    /// <summary>A check is value + dice + bonus against the difficulty; reaching it exactly succeeds.</summary>
+    public class StatCheckTests
+    {
+        [ModTest("check/total_and_threshold")]
+        static void TotalAndThreshold(ModTestContext ctx)
+        {
+            var check = new StatCheck { Stat = "cha", Difficulty = 12, Dice = "none", Bonus = 2 };
+
+            check.Perform(10, null);
+            ModAssert.Equal(12, check.Total, "10 + 0 + 2");
+            ModAssert.True(check.Success, "reaching the difficulty exactly succeeds");
+
+            check.Perform(9, null);
+            ModAssert.False(check.Success, "one short fails");
+            ModAssert.Equal(0, check.Roll, "no dice");
+        }
+
+        [ModTest("check/dice_add_to_the_total")]
+        static void DiceAddToTheTotal(ModTestContext ctx)
+        {
+            var check = new StatCheck { Stat = "str", Difficulty = 100, Dice = "1d6", Bonus = -1 };
+            var random = new Random(11);
+            for (var i = 0; i < 50; i++)
+            {
+                check.Perform(5, random);
+                ModAssert.True(check.Roll is >= 1 and <= 6, $"1d6 gave {check.Roll}");
+                ModAssert.Equal(5 + check.Roll - 1, check.Total, "value + roll + bonus");
+                ModAssert.False(check.Success, "100 is out of reach");
+            }
+        }
+    }
+}