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src/components/game-canvas/combatFeedback.test.ts

@@ -0,0 +1,62 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  buildCombatFeedbackEvents,
+  type CombatFeedbackHealthSample,
+} from './combatFeedback';
+
+function toSample(key: string, hp: number): CombatFeedbackHealthSample {
+  return {
+    key,
+    kind: key.startsWith('hostile') ? 'hostile' : 'player',
+    hp,
+  };
+}
+
+describe('combatFeedback', () => {
+  it('creates red damage and green healing deltas from committed hp changes', () => {
+    const previous = new Map([
+      ['player', toSample('player', 20)],
+      ['hostile:npc-liu', toSample('hostile:npc-liu', 8)],
+    ]);
+
+    const result = buildCombatFeedbackEvents(
+      previous,
+      [
+        toSample('player', 11),
+        toSample('hostile:npc-liu', 9),
+      ],
+      4,
+    );
+
+    expect(result.events).toEqual([
+      {
+        id: 'player:5',
+        targetKey: 'player',
+        kind: 'player',
+        delta: -9,
+      },
+      {
+        id: 'hostile:npc-liu:6',
+        targetKey: 'hostile:npc-liu',
+        kind: 'hostile',
+        delta: 1,
+      },
+    ]);
+    expect(result.nextSequence).toBe(6);
+  });
+
+  it('ignores first render samples and unchanged hp', () => {
+    const result = buildCombatFeedbackEvents(
+      new Map([['player', toSample('player', 20)]]),
+      [
+        toSample('player', 20),
+        toSample('companion:npc-chen', 6),
+      ],
+      0,
+    );
+
+    expect(result.events).toEqual([]);
+    expect(result.nextSequence).toBe(0);
+  });
+});