feat: bootstrap walking skeleton

src/engine/__tests__/save.test.ts

@@ -0,0 +1,108 @@
+import { describe, expect, it } from 'vitest';
+import { buildContent } from '../../content/schema';
+import { createGameState, startAction } from '../game';
+import {
+  applyOfflineProgress,
+  createSave,
+  deserializeSave,
+  fromExportString,
+  SAVE_VERSION,
+  serializeSave,
+  toExportString,
+} from '../save';
+
+function testContent() {
+  return buildContent({
+    resources: [{ id: 'gold', name: 'Gold', startAmount: 0 }],
+    actions: [
+      { id: 'forage', name: 'Forage', durationMs: 3000, yields: { resourceId: 'gold', amount: 1 } },
+    ],
+  });
+}
+
+function sampleState() {
+  const content = testContent();
+  const state = createGameState(content);
+  state.resources.gold = 12;
+  startAction(state, content, 'forage');
+  state.actionElapsedMs = 500;
+  return state;
+}
+
+describe('createSave()', () => {
+  it('stamps the current version and timestamp around a snapshot of state', () => {
+    const save = createSave(sampleState(), 1700);
+    expect(save.version).toBe(SAVE_VERSION);
+    expect(save.savedAt).toBe(1700);
+    expect(save.state.resources.gold).toBe(12);
+    expect(save.state.activeActionId).toBe('forage');
+  });
+
+  it('snapshots state so later mutation does not affect the save', () => {
+    const state = sampleState();
+    const save = createSave(state, 1700);
+    state.resources.gold = 999;
+    expect(save.state.resources.gold).toBe(12);
+  });
+});
+
+describe('serialize / deserialize round-trip', () => {
+  it('survives JSON serialization unchanged', () => {
+    const save = createSave(sampleState(), 1700);
+    const restored = deserializeSave(serializeSave(save));
+    expect(restored).toEqual(save);
+  });
+
+  it('survives the compressed export string unchanged', () => {
+    const save = createSave(sampleState(), 1700);
+    const restored = fromExportString(toExportString(save));
+    expect(restored).toEqual(save);
+  });
+});
+
+describe('invalid / tampered saves', () => {
+  it('rejects a non-JSON export string cleanly', () => {
+    expect(() => fromExportString('@@@not-a-valid-payload@@@')).toThrow();
+  });
+
+  it('rejects JSON that does not match the save schema', () => {
+    expect(() => deserializeSave('{"version":1,"savedAt":1,"state":{}}')).toThrow();
+  });
+
+  it('rejects an unsupported save version', () => {
+    const future = JSON.stringify({
+      version: 999,
+      savedAt: 1,
+      state: { resources: {}, activeActionId: null, actionElapsedMs: 0 },
+    });
+    expect(() => deserializeSave(future)).toThrow(/version/i);
+  });
+});
+
+describe('applyOfflineProgress()', () => {
+  it('credits whole ticks of elapsed time to the active action', () => {
+    const content = testContent();
+    const state = createGameState(content);
+    startAction(state, content, 'forage'); // 3000ms per gold
+    const credited = applyOfflineProgress(state, content, 1000, 1000 + 9000); // 9s
+    expect(credited).toBe(9000);
+    expect(state.resources.gold).toBe(3); // 9000 / 3000
+  });
+
+  it('credits nothing when the clock did not advance', () => {
+    const content = testContent();
+    const state = createGameState(content);
+    startAction(state, content, 'forage');
+    expect(applyOfflineProgress(state, content, 5000, 4000)).toBe(0);
+    expect(state.resources.gold).toBe(0);
+  });
+
+  it('clamps credited time to the offline cap', () => {
+    const content = testContent();
+    const state = createGameState(content);
+    startAction(state, content, 'forage');
+    const credited = applyOfflineProgress(state, content, 0, 10_000_000, 6000);
+    expect(credited).toBe(6000);
+    expect(state.resources.gold).toBe(2); // 6000 / 3000
+  });
+});