halkyon_base: a Serverpod module for sign-in, accounts and instance basics

What every Halkyon server has, taken from Halkyon Learn's: anonymous,
GitHub and email-code sign-in with their endpoints, an account's ways
in and its deletion, the pruning of abandoned anonymous people, of
sign-up attempts and of expired codes, and the instance's basics (the
sign-in ways offered, the source link, the minimum app build, where
people's data and its backups are). Endpoints sit under the nickname
`base`. A host configures it in one place before its pod starts: its
name for the mails, its source link, its minimum build, and hooks that
delete its own data with a person.

The tables keep Learn's names, columns and indexes, so a host moving
onto the module migrates nothing but version rows. Server package under
the SSPL, client under the AGPL, as Learn's are.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_base_server/test/integration/instance/instance_test.dart

@@ -0,0 +1,78 @@
+import 'package:halkyon_base_server/base.dart';
+import 'package:serverpod/serverpod.dart';
+import 'package:test/test.dart';
+
+import '../support/fixtures.dart';
+import '../test_tools/serverpod_test_tools.dart';
+
+/// Keeps nothing; there to say the instance can mail codes.
+final class _NoMail implements CodeMailer {
+  @override
+  Future<void> send(
+    Session session, {
+    required String to,
+    required String code,
+    required String language,
+  }) async {}
+}
+
+void main() {
+  withServerpod('What every instance tells its apps', (
+    sessionBuilder,
+    endpoints,
+  ) {
+    late InstanceBasics basics;
+
+    setUp(() async {
+      useBase(sessionBuilder);
+      basics = await endpoints.instance.basics(
+        sessionBuilder.copyWith(
+          authentication: AuthenticationOverride.unauthenticated(),
+        ),
+      );
+    });
+
+    test("names where the host's project publishes its source when the "
+        'operator set nothing', () {
+      // The tests run without SOURCE_URL.
+      expect(basics.sourceCodeUrl, testUpstreamSourceCodeUrl);
+    });
+
+    test('names the oldest app build the host works with, to anyone, so an '
+        'older app can say it needs an update', () {
+      expect(basics.minimumAppBuild, testMinimumAppBuild);
+    });
+
+    test('says nothing of where its data and backups are where the '
+        'operator said nothing', () {
+      // The tests run without DATA_LOCATION and BACKUP_LOCATION.
+      expect(basics.dataLocation, isNull);
+      expect(basics.backupLocation, isNull);
+    });
+
+    test('offers no GitHub sign-in without an OAuth app of its own', () {
+      // The tests' passwords hold no githubClientId.
+      expect(basics.gitHubClientId, isNull);
+    });
+
+    test('offers email sign-in only where it can mail codes', () async {
+      final codes = EmailCodes.of(sessionBuilder.build().serverpod);
+      final unauthenticated = sessionBuilder.copyWith(
+        authentication: AuthenticationOverride.unauthenticated(),
+      );
+      addTearDown(() => codes.mailer = null);
+
+      codes.mailer = null;
+      expect(
+        (await endpoints.instance.basics(unauthenticated)).emailSignIn,
+        isFalse,
+      );
+
+      codes.mailer = _NoMail();
+      expect(
+        (await endpoints.instance.basics(unauthenticated)).emailSignIn,
+        isTrue,
+      );
+    });
+  });
+}