puer_test 1.0.0

A package to make feature testing in puer easier and more enjoyable.

Puer Test

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Testing utilities for puer — concise, assertion-style tests for update functions and EffectHandlers.

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Features

✅ Concise update tests — Test your pure update function with a single .test() call
✅ Handler testing — Verify effect handlers emit the correct messages
✅ No boilerplate — No manual stream subscriptions, no async coordination
✅ Clear assertions — Expected state and effects are explicit parameters

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Installation

dev_dependencies:
  puer_test: ^1.0.0

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Testing update functions

Since update is a pure function, testing is straightforward — call it with a state and message, verify the result.

Example:

import 'package:puer_test/puer_test.dart';
import 'package:test/test.dart';

void main() {
  test('Increment increases count by 1', () {
    counterUpdate.test(
      state: const CounterState(count: 5),
      message: Increment(),
      expectedState: const CounterState(count: 6),
    );
  });

  test('LoadTodos sets loading flag and emits FetchTodos effect', () {
    todoUpdate.test(
      state: const TodoState(todos: [], isLoading: false),
      message: LoadTodos(),
      expectedState: const TodoState(todos: [], isLoading: true),
      expectedEffects: [FetchTodos()],
    );
  });
}

Parameters:

Parameter	Description
state	The current state before the message
message	The message to process
expectedState	The expected state after processing (optional if no state change)
expectedEffects	The expected list of effects (optional if no effects)

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Testing EffectHandlers

Effect handlers require mocks for their dependencies. This example uses mocktail.

Example:

import 'package:mocktail/mocktail.dart';
import 'package:puer_test/puer_test.dart';
import 'package:test/test.dart';

class MockTodoRepository extends Mock implements TodoRepository {}

void main() {
  test('FetchTodosHandler emits TodosLoaded on success', () async {
    final mockRepo = MockTodoRepository();
    when(() => mockRepo.fetchAll()).thenAnswer(
      (_) async => ['Task 1', 'Task 2'],
    );

    final handler = FetchTodosHandler(mockRepo);

    await handler.test(
      effect: FetchTodos(),
      expectedMessages: [TodosLoaded(['Task 1', 'Task 2'])],
    );
  });

  test('FetchTodosHandler emits TodosLoadFailed on error', () async {
    final mockRepo = MockTodoRepository();
    when(() => mockRepo.fetchAll()).thenThrow(Exception('Network error'));

    final handler = FetchTodosHandler(mockRepo);

    await handler.test(
      effect: FetchTodos(),
      expectedMessages: [TodosLoadFailed()],
    );
  });
}

Parameters:

Parameter	Description
effect	The effect to process
expectedMessages	The expected list of messages emitted by the handler

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Why test with puer_test?

Without puer_test:

test('Increment increases count', () {
  final result = counterUpdate(
    const CounterState(count: 5),
    Increment(),
  );
  
  expect(result.state, equals(const CounterState(count: 6)));
  expect(result.effects, isEmpty);
});

With puer_test:

test('Increment increases count', () {
  counterUpdate.test(
    state: const CounterState(count: 5),
    message: Increment(),
    expectedState: const CounterState(count: 6),
  );
});

Less noise, clearer intent.

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Packages

Package	Pub	Description
puer		Core TEA implementation with Feature, update, and effect handlers. Pure Dart foundation.
puer_flutter		Flutter integration: FeatureProvider, FeatureBuilder, FeatureListener widgets.
puer_effect_handlers		Composable wrappers for debouncing, sequential execution, and isolate offloading.
puer_test		Testing utilities for concise update and handler tests. Add to dev_dependencies.
puer_time_travel		Time-travel debugging with DevTools extension. Use in debug builds to inspect history.

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Learn more

• Main repository — Testing guide, patterns, examples

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License

MIT