migration consolidation patch

test/migrations.test.js

@@ -0,0 +1,65 @@
+// Migration runner — tests the REAL migrate() version-stepping logic against a
+// minimal fake db (emulating the better-sqlite3 pragma getter/setter + transaction
+// API), so it runs with zero dependencies. Guards that migrations apply in order,
+// advance user_version correctly, and no-op when the DB is already current.
+const { test } = require('node:test');
+const assert = require('node:assert');
+const { migrate, LATEST_VERSION } = require('../packages/memory-service/src/db/migrations');
+
+// Emulates just the slice of the better-sqlite3 API that migrate() uses.
+function fakeDb(startVersion = 0) {
+  let version = startVersion;
+  return {
+    ran: [],
+    setCalls: [],
+    pragma(str, opts) {
+      const set = str.match(/^user_version\s*=\s*(\d+)$/);
+      if (set) { version = Number(set[1]); this.setCalls.push(version); return; }
+      if (str === 'user_version') return opts && opts.simple ? version : [{ user_version: version }];
+      throw new Error('unexpected pragma: ' + str);
+    },
+    transaction(fn) { return (...args) => fn(...args); },  // execute immediately
+    get version() { return version; },
+  };
+}
+
+test('a fresh DB (user_version 0) is stamped to LATEST_VERSION', () => {
+  const db = fakeDb(0);
+  const result = migrate(db);
+  assert.strictEqual(result, LATEST_VERSION);
+  assert.strictEqual(db.version, LATEST_VERSION);
+});
+
+test('an already-current DB is a no-op (no version writes)', () => {
+  const db = fakeDb(LATEST_VERSION);
+  const result = migrate(db);
+  assert.strictEqual(result, LATEST_VERSION);
+  assert.deepStrictEqual(db.setCalls, [], 'should not touch user_version when current');
+});
+
+test('injected migrations run in order, each bumping the version by one', () => {
+  const db = fakeDb(0);
+  const order = [];
+  const migs = [
+    () => order.push('v1'),
+    () => order.push('v2'),
+    () => order.push('v3'),
+  ];
+  const result = migrate(db, migs);
+  assert.strictEqual(result, 3);
+  assert.deepStrictEqual(order, ['v1', 'v2', 'v3'], 'migrations apply in sequence');
+  assert.deepStrictEqual(db.setCalls, [1, 2, 3], 'user_version advances one step at a time');
+});
+
+test('only migrations newer than the current version run', () => {
+  const db = fakeDb(1);   // already at v1
+  const order = [];
+  const migs = [
+    () => order.push('v1'),   // should be skipped
+    () => order.push('v2'),
+    () => order.push('v3'),
+  ];
+  migrate(db, migs);
+  assert.deepStrictEqual(order, ['v2', 'v3'], 'v1 is not re-run');
+  assert.deepStrictEqual(db.setCalls, [2, 3]);
+});