Halkyon's shared packages

A pub workspace of the Dart packages Halkyon's apps share: halkyon_ui,
Halkyon's look (the theme, fonts, layout and shared widgets, with texts
in English and German), halkyon_core's low-level primitives and
halkyon_interop's cross-app contracts. Dart 3.13 with LeanCode's lints,
configured once at the root; apps take a package by git, pinned to a
signed commit.

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_ui/test/widget/found_by_id_test.dart

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+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:halkyon_ui/halkyon_ui.dart';
+import 'package:material_ui/material_ui.dart';
+
+import '../support/test_app.dart';
+
+void main() {
+  late StreamController<List<String>> items;
+
+  setUp(() => items = StreamController());
+  tearDown(() => items.close());
+
+  /// Opens the screen of the item [id] over a first screen.
+  Future<void> open(
+    WidgetTester tester,
+    String id, {
+    ({String label, VoidCallback onPressed})? wayBack,
+  }) async {
+    await tester.pumpWidget(
+      testApp(
+        Builder(
+          builder: (context) => TextButton(
+            onPressed: () => Navigator.of(context).push(
+              MaterialPageRoute<void>(
+                builder: (context) => FoundById<String>(
+                  id: id,
+                  items: () => items.stream,
+                  idOf: (item) => item,
+                  builder: (item, items) =>
+                      Scaffold(body: Text('Item $item of ${items.length}')),
+                  wayBack: wayBack,
+                ),
+              ),
+            ),
+            child: const Text('Open'),
+          ),
+        ),
+      ),
+    );
+    await tester.tap(find.text('Open'));
+    // Through the opening transition; the spinner never settles.
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1));
+  }
+
+  testWidgets('shows a spinner until the list arrives, then the item', (
+    tester,
+  ) async {
+    await open(tester, 'a');
+    expect(find.byType(AppLoadingIndicator), findsOneWidget);
+
+    items.add(['a', 'b']);
+    await tester.pump();
+
+    expect(find.text('Item a of 2'), findsOneWidget);
+    expect(find.byType(AppLoadingIndicator), findsNothing);
+  });
+
+  testWidgets('says that an item missing from the list no longer exists', (
+    tester,
+  ) async {
+    await open(tester, 'c');
+
+    items.add(['a', 'b']);
+    await tester.pump();
+
+    expect(find.textContaining('no longer exists'), findsOneWidget);
+  });
+
+  testWidgets('leads the way back from there, as the app says', (
+    tester,
+  ) async {
+    var ledBack = 0;
+    await open(
+      tester,
+      'c',
+      wayBack: (label: 'To the library', onPressed: () => ledBack++),
+    );
+    items.add(['a']);
+    await tester.pump();
+
+    await tester.tap(find.text('To the library'));
+
+    expect(ledBack, 1);
+  });
+
+  testWidgets('says so once the item goes while its screen is open', (
+    tester,
+  ) async {
+    await open(tester, 'a');
+    items.add(['a']);
+    await tester.pump();
+
+    // Deleted on another device, say.
+    items.add([]);
+    await tester.pump();
+
+    expect(find.text('Item a of 1'), findsNothing);
+    expect(find.textContaining('no longer exists'), findsOneWidget);
+  });
+
+  testWidgets('a screen that closes as its item goes keeps showing the item '
+      'on its way out', (tester) async {
+    await open(tester, 'a');
+    items.add(['a']);
+    await tester.pump();
+
+    // As when the screen deleted its item and closes.
+    Navigator.of(tester.element(find.text('Item a of 1'))).pop();
+    items.add([]);
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 100));
+
+    expect(find.text('Item a of 1'), findsOneWidget);
+    expect(find.textContaining('no longer exists'), findsNothing);
+    await tester.pumpAndSettle();
+    expect(find.text('Open'), findsOneWidget);
+  });
+}