Verify SQLite backups and restores

tests/database-backup.test.ts

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+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { describe, it } from "node:test";
+import Database from "better-sqlite3";
+import { migrate } from "drizzle-orm/better-sqlite3/migrator";
+import {
+  createVerifiedDatabaseBackup,
+  verifyDatabaseFile,
+} from "../src/db/database-backup.js";
+import { createDatabaseContext } from "../src/db/database-context.js";
+import { projects } from "../src/db/schema/projects.js";
+
+describe("database backup and restore", () => {
+  it("backs up committed WAL data and restores it as an independent database", async () => {
+    const testDirectory = fs.mkdtempSync(
+      path.join(os.tmpdir(), "leistungsbilanz-db-backup-")
+    );
+    const sourcePath = path.join(testDirectory, "source.db");
+    const backupPath = path.join(testDirectory, "backup.db");
+    const restoredPath = path.join(testDirectory, "restored.db");
+    const source = createDatabaseContext(sourcePath);
+
+    try {
+      source.sqlite.pragma("journal_mode = WAL");
+      migrate(source.db, {
+        migrationsFolder: path.resolve("src", "db", "migrations"),
+      });
+      source.db
+        .insert(projects)
+        .values({ id: "project-in-backup", name: "Backup project" })
+        .run();
+
+      assert.equal(fs.existsSync(`${sourcePath}-wal`), true);
+
+      const backupVerification = await createVerifiedDatabaseBackup(
+        sourcePath,
+        backupPath
+      );
+      assert.deepEqual(backupVerification, {
+        integrityCheck: "ok",
+        foreignKeyViolations: 0,
+      });
+
+      source.db
+        .insert(projects)
+        .values({ id: "project-after-backup", name: "Later project" })
+        .run();
+      source.close();
+
+      await createVerifiedDatabaseBackup(backupPath, restoredPath);
+      const restored = new Database(restoredPath, {
+        readonly: true,
+        fileMustExist: true,
+      });
+      try {
+        const restoredProjects = restored
+          .prepare("SELECT id, name FROM projects ORDER BY id")
+          .all();
+        assert.deepEqual(restoredProjects, [
+          { id: "project-in-backup", name: "Backup project" },
+        ]);
+      } finally {
+        restored.close();
+      }
+    } finally {
+      if (source.sqlite.open) {
+        source.close();
+      }
+      fs.rmSync(testDirectory, { recursive: true, force: true });
+    }
+  });
+
+  it("rejects a corrupt database file", () => {
+    const testDirectory = fs.mkdtempSync(
+      path.join(os.tmpdir(), "leistungsbilanz-db-verify-")
+    );
+    const corruptPath = path.join(testDirectory, "corrupt.db");
+
+    try {
+      fs.writeFileSync(corruptPath, "not a sqlite database");
+      assert.throws(() => verifyDatabaseFile(corruptPath), /not a database/);
+    } finally {
+      fs.rmSync(testDirectory, { recursive: true, force: true });
+    }
+  });
+});