chore: Halkyon Learn moves into apps/learn

Its server, client, app and curator, and the tools that write its
assets (maps, Anki fixtures, icons), as they are; paths are fixed in
the commits that follow.

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

apps/learn/halkyon_learn_flutter/test/feature/study/widget/study_button_block_test.dart

@@ -0,0 +1,161 @@
+import 'package:appflowy_editor/appflowy_editor.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:halkyon_learn_flutter/src/core/content/content_blocks.dart';
+import 'package:halkyon_learn_flutter/src/core/content/rich_content.dart';
+import 'package:halkyon_learn_flutter/src/core/editor/rich_content_document.dart';
+import 'package:halkyon_learn_flutter/src/core/router/route_paths.dart';
+import 'package:halkyon_learn_flutter/src/feature/card/data/card_repository.dart';
+import 'package:halkyon_learn_flutter/src/feature/card/model/card_content.dart';
+import 'package:halkyon_learn_flutter/src/feature/studyset/data/studyset_payload.dart';
+import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset_content.dart';
+import 'package:halkyon_learn_flutter/src/feature/tag/data/tag_repository.dart';
+import 'package:material_ui/material_ui.dart';
+
+import '../../../support/fake_card_gateway.dart';
+import '../../../support/fake_note_gateway.dart';
+import '../../../support/fake_studyset_gateway.dart';
+import '../../../support/fake_tag_gateway.dart';
+import '../../../support/pump_app.dart';
+import '../../../support/test_dependencies.dart';
+
+void main() {
+  late FakeStudysetGateway studysets;
+  late FakeCardGateway cardGateway;
+  late FakeTagGateway tagGateway;
+  late String verb;
+
+  setUp(() async {
+    studysets = FakeStudysetGateway()
+      ..receiveRemoteChange(
+        'japanese',
+        encodeStudysetPayload(StudysetContent.titled('Japanese')),
+      );
+    cardGateway = FakeCardGateway();
+    tagGateway = FakeTagGateway();
+    final cards = CardRepository(cardGateway);
+    final tags = TagRepository(tagGateway);
+    addTearDown(cards.dispose);
+    addTearDown(tags.dispose);
+    final taberu = await cards.create(
+      'japanese',
+      CardContent(
+        front: RichContent.plain('食べる'),
+        back: RichContent.plain('to eat'),
+      ),
+    );
+    await cards.create(
+      'japanese',
+      CardContent(
+        front: RichContent.plain('猫'),
+        back: RichContent.plain('cat'),
+      ),
+    );
+    verb = await tags.create('verb');
+    await tags.setTagsOf(taberu, {verb});
+  });
+
+  Future<void> showApp(WidgetTester tester, String location) async {
+    tester.view.physicalSize = const Size(1200, 1000);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await pumpApp(
+      tester,
+      testDependencies(
+        studysetGateway: studysets,
+        cardGateway: cardGateway,
+        tagGateway: tagGateway,
+        noteGateway: FakeNoteGateway(),
+      ),
+      location: location,
+    );
+    await tester.pump(const Duration(seconds: 1));
+  }
+
+  /// A studyset whose description holds a study button of [attributes].
+  void describedWithButton(Map<String, Object?> attributes) =>
+      studysets.receiveRemoteChange(
+        'lesson',
+        encodeStudysetPayload(
+          StudysetContent(
+            title: 'Lesson',
+            description: Document(
+              root: pageNode(
+                children: [
+                  Node(type: studyButtonBlockType, attributes: attributes),
+                ],
+              ),
+            ).toRichContent(),
+          ),
+        ),
+      );
+
+  testWidgets("goes into a note from Insert: the note's studyset studied "
+      'first, with a tag, a label, and without its topics', (tester) async {
+    await showApp(tester, RoutePaths.newNote('japanese'));
+    await tester.tap(find.byType(AppFlowyEditor));
+    await tester.pump(const Duration(seconds: 1));
+    final editorState = tester
+        .widget<AppFlowyEditor>(find.byType(AppFlowyEditor))
+        .editorState;
+
+    await tester.tap(find.byTooltip('Insert'));
+    await tester.pumpAndSettle();
+    await tester.ensureVisible(find.text('Study button'));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('Study button'));
+    await tester.pumpAndSettle();
+    expect(find.text('Japanese'), findsOneWidget);
+
+    await tester.tap(find.text('All cards'));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('verb').last);
+    await tester.pumpAndSettle();
+    await tester.enterText(find.widgetWithText(TextField, 'Label'), 'Verbs');
+    await tester.tap(find.text('With its topics'));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('Save'));
+    await tester.pumpAndSettle();
+
+    final block = editorState.document.root.children.first;
+    expect(block.type, studyButtonBlockType);
+    expect(block.attributes, {
+      studyButtonStudysetKey: 'japanese',
+      studyButtonTagKey: verb,
+      studyButtonTagNameKey: 'verb',
+      studyButtonLabelKey: 'Verbs',
+      studyButtonTopicsKey: false,
+      studyButtonBackFirstKey: false,
+    });
+    expect(find.text('Verbs'), findsOneWidget);
+    expect(find.text('Tagged verb · Without its topics'), findsOneWidget);
+  });
+
+  testWidgets('shown read-only, starts a session of the cards it says, '
+      'back first if asked', (tester) async {
+    describedWithButton({
+      studyButtonStudysetKey: 'japanese',
+      studyButtonTagKey: verb,
+      studyButtonTagNameKey: 'verb',
+      studyButtonLabelKey: 'Verbs',
+      studyButtonBackFirstKey: true,
+    });
+    await showApp(tester, RoutePaths.studyset('lesson'));
+
+    await tester.tap(find.widgetWithText(FilledButton, 'Verbs'));
+    await tester.pumpAndSettle();
+
+    // Only the verb, and its back first.
+    expect(find.textContaining('to eat', findRichText: true), findsOneWidget);
+    expect(find.textContaining('猫', findRichText: true), findsNothing);
+  });
+
+  testWidgets('a button whose studyset is gone says so', (tester) async {
+    describedWithButton({studyButtonStudysetKey: 'gone'});
+    await showApp(tester, RoutePaths.studyset('lesson'));
+
+    await tester.tap(find.widgetWithText(FilledButton, 'Study'));
+    await tester.pump();
+
+    expect(find.text('That studyset no longer exists.'), findsOneWidget);
+  });
+}