test: comprehensive tests for player effects, monster, and combat

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

combat/combat_test.go

@@ -76,3 +76,63 @@ func TestFleeChance(t *testing.T) {
 		t.Errorf("Flee success rate suspicious: %d/100", successes)
 	}
 }
+
+func TestMonsterAIBossAoE(t *testing.T) {
+	boss := &entity.Monster{Name: "Boss", HP: 100, IsBoss: true}
+	players := []*entity.Player{entity.NewPlayer("P1", entity.ClassWarrior)}
+
+	// Turn 0 should NOT AoE
+	_, isAoE := MonsterAI(boss, players, 0)
+	if isAoE {
+		t.Error("boss should not AoE on turn 0")
+	}
+	// Turn 3 should AoE
+	_, isAoE = MonsterAI(boss, players, 3)
+	if !isAoE {
+		t.Error("boss should AoE on turn 3")
+	}
+	// Turn 6 should AoE
+	_, isAoE = MonsterAI(boss, players, 6)
+	if !isAoE {
+		t.Error("boss should AoE on turn 6")
+	}
+}
+
+func TestMonsterAILowestHP(t *testing.T) {
+	p1 := entity.NewPlayer("Tank", entity.ClassWarrior) // 120 HP
+	p2 := entity.NewPlayer("Mage", entity.ClassMage)     // 70 HP
+	p2.HP = 10                                            // very low
+
+	// Run many times — at least some should target p2 (30% chance)
+	targetedLow := 0
+	for i := 0; i < 100; i++ {
+		m := &entity.Monster{Name: "Orc", HP: 50}
+		idx, _ := MonsterAI(m, []*entity.Player{p1, p2}, 1)
+		if idx == 1 {
+			targetedLow++
+		}
+	}
+	// Should target low HP player roughly 30% of time
+	if targetedLow < 10 || targetedLow > 60 {
+		t.Errorf("lowest HP targeting out of expected range: %d/100", targetedLow)
+	}
+}
+
+func TestCalcDamageWithMultiplier(t *testing.T) {
+	// AoE multiplier 0.8: ATK=20, DEF=5, mult=0.8 → base = 20*0.8 - 5 = 11
+	// Range: 11 * 0.85 to 11 * 1.15 = ~9.35 to ~12.65
+	for i := 0; i < 50; i++ {
+		dmg := CalcDamage(20, 5, 0.8)
+		if dmg < 9 || dmg > 13 {
+			t.Errorf("AoE damage %d out of expected range 9-13", dmg)
+		}
+	}
+}
+
+func TestCalcDamageHighDEF(t *testing.T) {
+	// When DEF > ATK*mult, should deal minimum 1 damage
+	dmg := CalcDamage(5, 100, 1.0)
+	if dmg != 1 {
+		t.Errorf("expected minimum damage 1, got %d", dmg)
+	}
+}