test(viewer): add bloc tests

test/viewer/bloc/viewer_bloc_test.dart

@@ -0,0 +1,60 @@
+import 'package:ariadne/analyzer/analyzer.dart';
+import 'package:ariadne/database/code/code_database.dart' as db;
+import 'package:ariadne/viewer/bloc/viewer_bloc.dart';
+import 'package:bloc_test/bloc_test.dart';
+import 'package:drift/native.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+
+class MockAnalyzer extends Mock implements Analyzer {}
+
+void main() {
+  late ViewerBloc viewerBloc;
+  late MockAnalyzer mockAnalyzer;
+  late db.CodeDatabase codeDB;
+
+  setUp(() {
+    mockAnalyzer = MockAnalyzer();
+    codeDB = db.CodeDatabase.forTesting(NativeDatabase.memory());
+    viewerBloc = ViewerBloc(analyzer: mockAnalyzer, codeDB: codeDB);
+  });
+
+  tearDown(() {
+    codeDB.close();
+  });
+
+  blocTest<ViewerBloc, ViewerState>(
+    'Overview emits [loading, success]',
+    build: () {
+      return viewerBloc;
+    },
+    act: (bloc) => bloc.add(const Overview()),
+    expect: () => [
+      const ViewerState().copyWith(status: .loading),
+      const ViewerState().copyWith(status: .success),
+    ],
+  );
+
+  blocTest<ViewerBloc, ViewerState>(
+    'Lists emits [loading, success] and a list of nodes',
+    build: () {
+      return viewerBloc;
+    },
+    act: (bloc) => bloc.add(const Lists(title: 'classes', kind: 5)),
+    expect: () => [
+      const ViewerState().copyWith(status: .loading),
+      isA<ViewerState>()
+          .having((s) => s.status, 'status', equals(ViewerStatus.success))
+          .having((s) => s.nodes, 'nodes', isNotEmpty),
+    ],
+  );
+
+  blocTest<ViewerBloc, ViewerState>(
+    'ResetViewer emits initial state',
+    build: () {
+      return viewerBloc;
+    },
+    act: (bloc) => bloc.add(const ResetViewer()),
+    expect: () => [const ViewerState()],
+  );
+}