test-loading-state

name	test-loading-state
description	Test isWaiting() behavior using Completers to verify loading states work correctly

Test Loading State (isWaiting)

This skill tests isWaiting() behavior in Cubit methods.

What This Skill Does

Tests that:

• isWaiting() returns true while operation is in progress
• isWaiting() returns false after operation completes
• Loading state works with composite keys

Instructions

Step 1: Set Up Test with Completer

Use Completer to control when async operations complete:

import 'dart:async';
import 'package:bloc_superpowers/bloc_superpowers.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:mocktail/mocktail.dart';

void main() {
  late UserCubit cubit;
  late MockApi mockApi;

  setUp(() {
    Superpowers.clear();
    mockApi = MockApi();
    cubit = UserCubit(api: mockApi);
  });

  tearDown(() => cubit.close());

  test('isWaiting is true during operation', () async {
    // Create a completer to control when the future completes
    final completer = Completer<User>();

    // Mock returns a future we control
    when(() => mockApi.getUser()).thenAnswer((_) => completer.future);

    // Start the operation
    cubit.loadUser();

    // Allow async to process
    await Future.delayed(Duration.zero);

    // Verify loading state is true
    expect(Superpowers.isWaiting(UserCubit), isTrue);

    // Complete the operation
    completer.complete(User(name: 'John'));

    // Allow async to process
    await Future.delayed(Duration.zero);

    // Verify loading state is false
    expect(Superpowers.isWaiting(UserCubit), isFalse);
  });
}

Step 2: Test Pattern

test('loading state pattern', () async {
  final completer = Completer<Data>();
  when(() => mockApi.getData()).thenAnswer((_) => completer.future);

  // 1. Start operation
  cubit.loadData();
  await Future.delayed(Duration.zero);

  // 2. Assert loading is true
  expect(Superpowers.isWaiting(key), isTrue);

  // 3. Complete operation
  completer.complete(data);
  await Future.delayed(Duration.zero);

  // 4. Assert loading is false
  expect(Superpowers.isWaiting(key), isFalse);
});

Testing Different Key Types

Type Key

// Cubit uses: key: this (becomes UserCubit)
test('loading with type key', () async {
  final completer = Completer<User>();
  when(() => mockApi.getUser()).thenAnswer((_) => completer.future);

  cubit.loadUser();
  await Future.delayed(Duration.zero);

  expect(Superpowers.isWaiting(UserCubit), isTrue);

  completer.complete(User(name: 'John'));
  await Future.delayed(Duration.zero);

  expect(Superpowers.isWaiting(UserCubit), isFalse);
});

Enum Key

// Cubit uses: key: UserAction.load
test('loading with enum key', () async {
  final completer = Completer<User>();
  when(() => mockApi.getUser()).thenAnswer((_) => completer.future);

  cubit.loadUser();
  await Future.delayed(Duration.zero);

  expect(Superpowers.isWaiting(UserAction.load), isTrue);

  completer.complete(User(name: 'John'));
  await Future.delayed(Duration.zero);

  expect(Superpowers.isWaiting(UserAction.load), isFalse);
});

Composite Key (Record)

// Cubit uses: key: (DeleteItem, itemId)
test('loading with composite key', () async {
  final completer = Completer<void>();
  when(() => mockApi.deleteItem('123')).thenAnswer((_) => completer.future);

  cubit.deleteItem('123');
  await Future.delayed(Duration.zero);

  // Only this specific item is loading
  expect(Superpowers.isWaiting((DeleteItem, '123')), isTrue);
  expect(Superpowers.isWaiting((DeleteItem, '456')), isFalse);

  completer.complete();
  await Future.delayed(Duration.zero);

  expect(Superpowers.isWaiting((DeleteItem, '123')), isFalse);
});

Testing Multiple Operations

test('multiple operations have independent loading states', () async {
  final loadCompleter = Completer<User>();
  final saveCompleter = Completer<void>();

  when(() => mockApi.getUser()).thenAnswer((_) => loadCompleter.future);
  when(() => mockApi.saveUser(any())).thenAnswer((_) => saveCompleter.future);

  // Start both operations
  cubit.loadUser();
  cubit.saveUser(User(name: 'John'));
  await Future.delayed(Duration.zero);

  // Both are loading
  expect(Superpowers.isWaiting(UserAction.load), isTrue);
  expect(Superpowers.isWaiting(UserAction.save), isTrue);

  // Complete load
  loadCompleter.complete(User(name: 'John'));
  await Future.delayed(Duration.zero);

  // Load done, save still loading
  expect(Superpowers.isWaiting(UserAction.load), isFalse);
  expect(Superpowers.isWaiting(UserAction.save), isTrue);

  // Complete save
  saveCompleter.complete();
  await Future.delayed(Duration.zero);

  // Both done
  expect(Superpowers.isWaiting(UserAction.load), isFalse);
  expect(Superpowers.isWaiting(UserAction.save), isFalse);
});

Testing Loading Clears on Error

test('loading state clears on error', () async {
  when(() => mockApi.getUser()).thenThrow(Exception('Error'));

  cubit.loadUser();
  await Future.delayed(Duration.zero);

  // Loading should be false (operation completed, with error)
  expect(Superpowers.isWaiting(UserCubit), isFalse);
  // Error state should be true
  expect(Superpowers.isFailed(UserCubit), isTrue);
});

Complete Test File

import 'dart:async';
import 'package:bloc_superpowers/bloc_superpowers.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:mocktail/mocktail.dart';

class MockApi extends Mock implements Api {}

void main() {
  late ProductCubit cubit;
  late MockApi mockApi;

  setUp(() {
    Superpowers.clear();
    mockApi = MockApi();
    cubit = ProductCubit(api: mockApi);
  });

  tearDown(() => cubit.close());

  group('loading state', () {
    test('isWaiting is true while loading products', () async {
      final completer = Completer<List<Product>>();
      when(() => mockApi.getProducts()).thenAnswer((_) => completer.future);

      cubit.loadProducts();
      await Future.delayed(Duration.zero);

      expect(Superpowers.isWaiting(ProductCubit), isTrue);

      completer.complete([Product(id: '1', name: 'Widget')]);
      await Future.delayed(Duration.zero);

      expect(Superpowers.isWaiting(ProductCubit), isFalse);
    });

    test('per-item loading for delete', () async {
      final completer = Completer<void>();
      when(() => mockApi.deleteProduct('1')).thenAnswer((_) => completer.future);

      cubit.deleteProduct('1');
      await Future.delayed(Duration.zero);

      expect(Superpowers.isWaiting((DeleteProduct, '1')), isTrue);
      expect(Superpowers.isWaiting((DeleteProduct, '2')), isFalse);

      completer.complete();
      await Future.delayed(Duration.zero);

      expect(Superpowers.isWaiting((DeleteProduct, '1')), isFalse);
    });

    test('loading clears on error', () async {
      when(() => mockApi.getProducts()).thenThrow(Exception('Error'));

      cubit.loadProducts();
      await Future.delayed(Duration.zero);

      expect(Superpowers.isWaiting(ProductCubit), isFalse);
      expect(Superpowers.isFailed(ProductCubit), isTrue);
    });
  });
}

Key Points

1. Use Completer to control async timing
2. Use Future.delayed(Duration.zero) to let async process
3. Use Superpowers.isWaiting(key) static method in tests
4. Match the key exactly as used in the Cubit's mix() call
5. Reset with Superpowers.clear() in setUp