sqlite3_test 0.1.0

Integration of fake clocks and other test utilities for SQLite databases.

This package provides utilities for accessing SQLite databases in Dart tests.

Features

Given that SQLite has no external dependencies and runs in the process of your app, it can easily be used in unit tests (avoiding the hassle of writing mocks for your database and repositories).

However, being a C library, SQLite is unaware of other Dart utilities typically used in tests (like a fake time with package:clock or a custom file system based on package:file). When your database queries depend on CURRENT_TIMESTAMP, this makes it hard to reliably test them as clock.now() and CURRENT_TIMESTAMP would report different values.

As a solution, this small package makes SQLite easier to integrate into your tests by providing a VFS that will:

1. Make CURRENT_TIME, CURRENT_DATE and CURRENT_TIMESTAMP reflect the time returned by package:clock.
2. For IO operations, allow providing a FileSystem from package:file. This includes custom implementations and the default one respecting IOOverrides.

Usage

This package is intended to be used in tests, so begin by adding a dev dependency on it:

$ dart pub add --dev sqlite3_test

You can then use it in tests by creating an instance of TestSqliteFileSystem for your databases:

import 'package:fake_async/fake_async.dart';
import 'package:sqlite3/sqlite3.dart';
import 'package:sqlite3_test/sqlite3_test.dart';
import 'package:file/local.dart';
import 'package:test/test.dart';

void main() {
  late TestSqliteFileSystem vfs;

  setUpAll(() {
    vfs = TestSqliteFileSystem(fs: const LocalFileSystem());
    sqlite3.registerVirtualFileSystem(vfs);
  });
  tearDownAll(() => sqlite3.unregisterVirtualFileSystem(vfs));

  test('my test depending on database time', () {
    final database = sqlite3.openInMemory(vfs: vfs.name);
    addTearDown(database.dispose);

    // The VFS uses package:clock to get the current time, which can be
    // overridden for tests:
    final moonLanding = DateTime.utc(1969, 7, 20, 20, 18, 04);
    FakeAsync(initialTime: moonLanding).run((_) {
      final row = database.select('SELECT unixepoch(current_timestamp)').first;

      expect(row.columnAt(0), -14182916);
    });
  });
}

Limitations

The layer of indirection through Dart will likely make your databases slower. For this reason, this package is intended to be used in tests (as the overhead is not a problem there).

Also, note that TestSqliteFileSystem cannot be used with WAL databases as the file system does not implement memory-mapped IO.