Refactor combat resolver attack pipeline

Roguelike.Core.Tests/Game/Combats/CombatResolverTests.cs

@@ -0,0 +1,173 @@
+using System.Collections.Generic;
+using System.Reflection;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Roguelike.Core.Game.Characters;
+using Roguelike.Core.Game.Collectables.Items;
+using Roguelike.Core.Game.Combat;
+
+namespace Roguelike.Core.Tests.Game.Combats;
+
+[TestClass]
+public class CombatResolverTests
+{
+    [TestMethod]
+    public void ExecuteAttack_ReturnsTrollMushroomEffect_OnOddRound()
+    {
+        var resolver = CreateResolver(1.0);
+        var attacker = CreateCharacter("Attacker", life: 20, maxLife: 20, strength: 12, armor: 2, speed: 6);
+        attacker.Inventory.Add(new Item { Id = ItemId.TrollMushroom, Value = 150 });
+        var defender = CreateCharacter("Defender", life: 18, maxLife: 18, strength: 8, armor: 4, speed: 4);
+
+        var outcome = resolver.ExecuteAttack(attacker, defender, round: 1);
+
+        Assert.IsTrue(outcome.TrollMushroomEffect);
+        Assert.AreEqual(0, outcome.Damage);
+        Assert.AreEqual(18, defender.LifePoint);
+    }
+
+    [TestMethod]
+    public void ExecuteAttack_DealsBaseDamageWithoutCritOrSpecials()
+    {
+        var resolver = CreateResolver(1.0);
+        var attacker = CreateCharacter("Attacker", life: 22, maxLife: 22, strength: 10, armor: 2, speed: 5);
+        var defender = CreateCharacter("Defender", life: 30, maxLife: 30, strength: 12, armor: 3, speed: 4);
+
+        var outcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.IsFalse(outcome.Crit);
+        Assert.AreEqual(7, outcome.Damage);
+        Assert.AreEqual(23, defender.LifePoint);
+        Assert.AreEqual(0, outcome.ArmorShredded);
+        Assert.AreEqual(0, outcome.LifeStolen);
+        Assert.AreEqual(0, outcome.ThornsReflected);
+        Assert.IsFalse(outcome.DefenderSavedByTalisman);
+    }
+
+    [TestMethod]
+    public void ExecuteAttack_TalismanTriggersOnlyOnceWhenDefenderWouldDie()
+    {
+        var resolver = CreateResolver(1.0, 1.0);
+        var attacker = CreateCharacter("Attacker", life: 25, maxLife: 25, strength: 40, armor: 2, speed: 5);
+        var defender = CreateCharacter("Defender", life: 20, maxLife: 40, strength: 12, armor: 5, speed: 4);
+        defender.Inventory.Add(new Item { Id = ItemId.TalismanOfTheLastBreath, Value = 15 });
+
+        var firstOutcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.IsTrue(firstOutcome.DefenderSavedByTalisman);
+        Assert.AreEqual(15, defender.LifePoint);
+
+        var secondOutcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.IsFalse(secondOutcome.DefenderSavedByTalisman);
+        Assert.AreEqual(0, defender.LifePoint);
+    }
+
+    [TestMethod]
+    public void ExecuteAttack_AppliesOldGiantWoodenClubArmorShred()
+    {
+        var resolver = CreateResolver(1.0);
+        var attacker = CreateCharacter("Attacker", life: 18, maxLife: 18, strength: 5, armor: 2, speed: 5);
+        attacker.Inventory.Add(new Item { Id = ItemId.OldGiantWoodenClub, Value = 4 });
+        var defender = CreateCharacter("Defender", life: 25, maxLife: 25, strength: 10, armor: 10, speed: 4);
+
+        var outcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.AreEqual(1, outcome.Damage);
+        Assert.AreEqual(4, outcome.ArmorShredded);
+        Assert.AreEqual(6, defender.Armor);
+    }
+
+    [TestMethod]
+    public void ExecuteAttack_LifeStealRestoresHealthWhenChanceSucceeds()
+    {
+        var resolver = CreateResolver(0.0);
+        var attacker = CreateCharacter("Attacker", life: 5, maxLife: 20, strength: 12, armor: 2, speed: 5);
+        attacker.Inventory.Add(new Item { Id = ItemId.DaggerLifeSteal, Value = 3 });
+        var defender = CreateCharacter("Defender", life: 18, maxLife: 18, strength: 15, armor: 4, speed: 4);
+
+        var outcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.AreEqual(8, outcome.Damage);
+        Assert.AreEqual(3, outcome.LifeStolen);
+        Assert.AreEqual(8, attacker.LifePoint);
+    }
+
+    [TestMethod]
+    public void ExecuteAttack_ThornsReflectDamageWhenChanceSucceeds()
+    {
+        var resolver = CreateResolver(0.0);
+        var attacker = CreateCharacter("Attacker", life: 20, maxLife: 20, strength: 10, armor: 2, speed: 5);
+        var defender = CreateCharacter("Defender", life: 18, maxLife: 18, strength: 15, armor: 4, speed: 4);
+        defender.Inventory.Add(new Item { Id = ItemId.ThornBreastplate, Value = 4 });
+
+        var outcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.AreEqual(6, outcome.Damage);
+        Assert.AreEqual(4, outcome.ThornsReflected);
+        Assert.AreEqual(16, attacker.LifePoint);
+    }
+
+    [TestMethod]
+    public void ExecuteAttack_DodgeRestoresHealthWithFeathersOfHope()
+    {
+        var resolver = CreateResolver(0.0);
+        var attacker = CreateCharacter("Attacker", life: 20, maxLife: 20, strength: 8, armor: 2, speed: 5);
+        var defender = CreateCharacter("Defender", life: 10, maxLife: 15, strength: 8, armor: 4, speed: 12);
+        defender.Inventory.Add(new Item { Id = ItemId.FeathersOfHope, Value = 3 });
+
+        var outcome = resolver.ExecuteAttack(attacker, defender, round: 2);
+
+        Assert.IsTrue(outcome.Dodged);
+        Assert.AreEqual(0, outcome.Damage);
+        Assert.AreEqual(13, defender.LifePoint);
+        Assert.AreEqual(3, outcome.LifeStolen);
+    }
+
+    private static CombatResolver CreateResolver(params double[] randomSequence)
+    {
+        var resolver = new CombatResolver();
+        var sequence = new SequenceRandom(randomSequence);
+        var randomField = typeof(CombatResolver).GetField("_random", BindingFlags.Instance | BindingFlags.NonPublic);
+        randomField!.SetValue(resolver, sequence);
+        return resolver;
+    }
+
+    private static TestCharacter CreateCharacter(string name, int life, int maxLife, int strength, int armor, int speed)
+    {
+        return new TestCharacter
+        {
+            Name = name,
+            LifePoint = life,
+            MaxLifePoint = maxLife,
+            Strength = strength,
+            Armor = armor,
+            Speed = speed,
+        };
+    }
+
+    private sealed class TestCharacter : Character
+    {
+        private string _name = string.Empty;
+
+        public override string Name
+        {
+            get => _name;
+            set => _name = value;
+        }
+    }
+
+    private sealed class SequenceRandom : Random
+    {
+        private readonly Queue<double> _values;
+
+        public SequenceRandom(params double[] values)
+        {
+            _values = new Queue<double>(values.Length == 0 ? new[] { 1.0 } : values);
+        }
+
+        protected override double Sample()
+        {
+            return _values.Count > 0 ? _values.Dequeue() : 1.0;
+        }
+    }
+}