spring_boot_starter_test 0.1.3

Testing for spring_boot_dart apps and starters: springBootTest, bean overrides for mocks, ApplicationContextRunner, matchers and log capture. Works with flutter_test.

spring_boot_starter_test

Testing support for spring_boot_dart applications and starters, like spring-boot-starter-test. Built on test_api and matcher (not package:test itself), so it works with both package:test and flutter_test.

dev_dependencies:
  spring_boot_starter_test: ^0.1.0
  test: ^1.25.0          # or flutter_test

springBootTest: the whole application (@SpringBootTest)

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

import '../bin/shop.beans.dart'; // generated springApplication

void main() {
  final gateway = FakeGateway();

  final app = springBootTest(
    springApplication,
    args: ['--shop.name=Night Books'],
    properties: {'logging.console.enabled': false}, // @SpringBootTest(properties)
    profiles: ['test'],                             // @ActiveProfiles
    systemEnvironment: {'SHOP_MAX_BASKET_SIZE': '25'},
    overrides: [BeanOverride<PaymentGateway>(gateway)], // @MockitoBean
  );

  test('pays through the fake', () {
    app.getBean<Checkout>().pay(10);
    expect(gateway.charged, [10]);
  });

  test('changes shared state', () {
    app.getBean<Basket>().add(book);
    app.markDirty(); // @DirtiesContext: the next test gets a fresh context
  });
}

• Test config lives in test/resources/ (see below).
• The context starts once before the first test of the main / group (config files, auto-configuration, runners: all of runApplication) and closes after the last one.
• properties win over every other source, the command line included.
• systemEnvironment is empty by default, so tests do not depend on the machine.
• SpringLog levels and handler are restored afterwards.
• app.output holds what the application printed (startup line, failure report); it is also printed when a test fails.

test/resources/: config and data for tests only

Like src/test/resources in Spring, test/resources/ comes first on the classpath while springBootTest runs, and is never embedded into the application (the generator embeds only lib/resources/):

lib/resources/application.properties          # the application's config
test/resources/application-test.properties    # test-only settings
test/resources/fixtures/books.json            # classpath:fixtures/books.json in tests

final app = springBootTest(
  springApplication,
  profiles: ['test'],                                // + application-test.properties
  propertyFiles: ['classpath:payments-test.properties'], // @TestPropertySource(locations)
);

• Prefer application-test.properties with profiles: ['test']: its keys are added on top of application.properties. A file with the same path as a lib/resources/ file replaces it entirely (as in Spring), so a test/resources/application.properties hides the real one.
• profiles replaces spring.profiles.active (like @ActiveProfiles): list the application's profiles too if you need them (profiles: ['dev', 'test']).
• Precedence: properties > propertyFiles (later files win) > command line args > environment > config files.
• Relative directories are resolved against the package of the test file (the nearest pubspec.yaml), so it does not matter whether the tests run from the package, a workspace root or an IDE.
• Other directories: resourceDirectories: ['test/fixtures', 'test/resources'] (the first listed comes first). In browser tests there is no file system, so the directories are simply not found.

BeanOverride: fakes and mocks (@MockitoBean, @TestBean)

BeanOverride<PaymentGateway>(FakeGateway())                 // the only bean of the type
BeanOverride<PaymentGateway>(MockGateway(), name: 'sandbox') // one of several

The original definition is removed before any bean is created, so the real object is never built. The replacement keeps the name, aliases, qualifiers and @Primary / @Fallback, so @Qualifier injection points still get it. Use any fake or mock library (e.g. mocktail). Overriding a type with several beans without name: fails and lists them.

ApplicationContextRunner: testing auto-configuration

The tool for starter authors (Spring Boot's ApplicationContextRunner). Immutable; no config files; empty environment unless set.

final runner = const ApplicationContextRunner()
    .withAutoConfiguration(neonCacheAutoConfiguration);

test('default cache', () {
  runner.run((context) {
    expect(context, hasSingleBean<Cache>());
  });
});

test('backs off for the application cache', () {
  runner.withBean<Cache>(AppCache()).run((context) {
    expect(context.getBean<Cache>(), isA<AppCache>());
  });
});

test('needs a size', () {
  runner.withPropertyValues(['neon.cache.size=-1']).run((context) {
    expect(context, hasFailed(isA<BeanCreationException>()));
  });
});

Also withUserConfiguration(module) (registered before the auto-configuration), withSystemEnvironment, withInitializer.

Matchers

hasSingleBean<T>(), hasBean<T>(), doesNotHaveBean<T>(), hasBeanNamed('name'), hasFailed([matcher]). They accept an AssertableApplicationContext, a springBootTest context or any ListableBeanFactory, and say which beans were found when they fail.

captureLogs

final logs = captureLogs(level: SpringLogLevel.debug);

test('warns about slow payments', () {
  checkout.pay(slowOrder);
  expect(logs.messages, contains('slow payment'));
  expect(logs.atLevel(SpringLogLevel.warning), hasLength(1));
  expect(logs.ofLogger('neon.checkout'), isNotEmpty);
});

Every test starts with an empty capture.

Name clash

package:test (via matcher) and spring_core_dart both define Description (Spring's @Description). It only matters if a test uses it: import 'package:test/test.dart' hide Description;.