On this page
41. Testing
Spring Boot provides a number of utilities and annotations to help when testing your application. Test support is provided by two modules; spring-boot-test
contains core items, and spring-boot-test-autoconfigure
supports auto-configuration for tests.
Most developers will just use the spring-boot-starter-test
‘Starter’ which imports both Spring Boot test modules as well has JUnit, AssertJ, Hamcrest and a number of other useful libraries.
If you use the spring-boot-starter-test
‘Starter’ (in the test
scope
), you will find the following provided libraries:
- JUnit — The de-facto standard for unit testing Java applications.
- Spring Test & Spring Boot Test — Utilities and integration test support for Spring Boot applications.
- AssertJ — A fluent assertion library.
- Hamcrest — A library of matcher objects (also known as constraints or predicates).
- Mockito — A Java mocking framework.
- JSONassert — An assertion library for JSON.
- JsonPath — XPath for JSON.
Note | |
---|---|
By default, Spring Boot uses Mockito 1.x. However it’s also possible to use 2.x if you wish. |
These are common libraries that we generally find useful when writing tests. You are free to add additional test dependencies of your own if these don’t suit your needs.
One of the major advantages of dependency injection is that it should make your code easier to unit test. You can simply instantiate objects using the new
operator without even involving Spring. You can also use mock objects instead of real dependencies.
Often you need to move beyond ‘unit testing’ and start ‘integration testing’ (with a Spring ApplicationContext
actually involved in the process). It’s useful to be able to perform integration testing without requiring deployment of your application or needing to connect to other infrastructure.
The Spring Framework includes a dedicated test module for just such integration testing. You can declare a dependency directly to org.springframework:spring-test
or use the spring-boot-starter-test
‘Starter’ to pull it in transitively.
If you have not used the spring-test
module before you should start by reading the relevant section of the Spring Framework reference documentation.
A Spring Boot application is just a Spring ApplicationContext
, so nothing very special has to be done to test it beyond what you would normally do with a vanilla Spring context. One thing to watch out for though is that the external properties, logging and other features of Spring Boot are only installed in the context by default if you use SpringApplication
to create it.
Spring Boot provides a @SpringBootTest
annotation which can be used as an alternative to the standard spring-test
@ContextConfiguration
annotation when you need Spring Boot features. The annotation works by creating the ApplicationContext
used in your tests via SpringApplication
.
You can use the webEnvironment
attribute of @SpringBootTest
to further refine how your tests will run:
MOCK
— Loads aWebApplicationContext
and provides a mock servlet environment. Embedded servlet containers are not started when using this annotation. If servlet APIs are not on your classpath this mode will transparently fallback to creating a regular non-webApplicationContext
. Can be used in conjunction with@AutoConfigureMockMvc
forMockMvc
-based testing of your application.RANDOM_PORT
— Loads anEmbeddedWebApplicationContext
and provides a real servlet environment. Embedded servlet containers are started and listening on a random port.DEFINED_PORT
— Loads anEmbeddedWebApplicationContext
and provides a real servlet environment. Embedded servlet containers are started and listening on a defined port (i.e from yourapplication.properties
or on the default port8080
).NONE
— Loads anApplicationContext
usingSpringApplication
but does not provide any servlet environment (mock or otherwise).
Note | |
---|---|
If your test is |
Note | |
---|---|
In addition to |
Tip | |
---|---|
Don’t forget to also add |
If you’re familiar with the Spring Test Framework, you may be used to using @ContextConfiguration(classes=…)
in order to specify which Spring @Configuration
to load. Alternatively, you might have often used nested @Configuration
classes within your test.
When testing Spring Boot applications this is often not required. Spring Boot’s @*Test
annotations will search for your primary configuration automatically whenever you don’t explicitly define one.
The search algorithm works up from the package that contains the test until it finds a @SpringBootApplication
or @SpringBootConfiguration
annotated class. As long as you’ve structured your code in a sensible way your main configuration is usually found.
Note | |
---|---|
If you use a test annotation to test a more specific slice of your application with such setup, you should avoid adding configuration that are specific to a particular area on the main’s application class. |
If you want to customize the primary configuration, you can use a nested @TestConfiguration
class. Unlike a nested @Configuration
class which would be used instead of a your application’s primary configuration, a nested @TestConfiguration
class will be used in addition to your application’s primary configuration.
Note | |
---|---|
Spring’s test framework will cache application contexts between tests. Therefore, as long as your tests share the same configuration (no matter how it’s discovered), the potentially time consuming process of loading the context will only happen once. |
If your application uses component scanning, for example if you use @SpringBootApplication
or @ComponentScan
, you may find top-level configuration classes created only for specific tests accidentally get picked up everywhere.
As we have seen above, @TestConfiguration
can be used on an inner class of a test to customize the primary configuration. When placed on a top-level class, @TestConfiguration
indicates that classes in src/test/java
should not be picked up by scanning. You can then import that class explicitly where it is required:
@RunWith(SpringRunner.class)
@SpringBootTest
@Import(MyTestsConfiguration.class)
public class MyTests {
@Test
public void exampleTest() {
...
}
}
Note | |
---|---|
If you directly use |
If you need to start a full running server for tests, we recommend that you use random ports. If you use @SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT)
an available port will be picked at random each time your test runs.
The @LocalServerPort
annotation can be used to inject the actual port used into your test. For convenience, tests that need to make REST calls to the started server can additionally @Autowire
a TestRestTemplate
which will resolve relative links to the running server.
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.test.context.junit4.SpringRunner;
import static org.assertj.core.api.Assertions.assertThat;
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class RandomPortExampleTests {
@Autowired
private TestRestTemplate restTemplate;
@Test
public void exampleTest() {
String body = this.restTemplate.getForObject("/", String.class);
assertThat(body).isEqualTo("Hello World");
}
}
It’s sometimes necessary to mock certain components within your application context when running tests. For example, you may have a facade over some remote service that’s unavailable during development. Mocking can also be useful when you want to simulate failures that might be hard to trigger in a real environment.
Spring Boot includes a @MockBean
annotation that can be used to define a Mockito mock for a bean inside your ApplicationContext
. You can use the annotation to add new beans, or replace a single existing bean definition. The annotation can be used directly on test classes, on fields within your test, or on @Configuration
classes and fields. When used on a field, the instance of the created mock will also be injected. Mock beans are automatically reset after each test method.
Note | |
---|---|
This feature is automatically enabled as long as your test uses one of Spring Boot’s test annotations (i.e.
|
Here’s a typical example where we replace an existing RemoteService
bean with a mock implementation:
import org.junit.*;
import org.junit.runner.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.context.*;
import org.springframework.boot.test.mock.mockito.*;
import org.springframework.test.context.junit4.*;
import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
@RunWith(SpringRunner.class)
@SpringBootTest
public class MyTests {
@MockBean
private RemoteService remoteService;
@Autowired
private Reverser reverser;
@Test
public void exampleTest() {
// RemoteService has been injected into the reverser bean
given(this.remoteService.someCall()).willReturn("mock");
String reverse = reverser.reverseSomeCall();
assertThat(reverse).isEqualTo("kcom");
}
}
Additionally you can also use @SpyBean
to wrap any existing bean with a Mockito spy
. See the Javadoc for full details.
Spring Boot’s auto-configuration system works well for applications, but can sometimes be a little too much for tests. It’s often helpful to load only the parts of the configuration that are required to test a ‘slice’ of your application. For example, you might want to test that Spring MVC controllers are mapping URLs correctly, and you don’t want to involve database calls in those tests; or you might be wanting to test JPA entities, and you’re not interested in web layer when those tests run.
The spring-boot-test-autoconfigure
module includes a number of annotations that can be used to automatically configure such ‘slices’. Each of them works in a similar way, providing a @…Test
annotation that loads the ApplicationContext
and one or more @AutoConfigure…
annotations that can be used to customize auto-configuration settings.
Note | |
---|---|
Each slice loads a very restricted set of auto-configuration classes. If you need to exclude one of them, most |
Tip | |
---|---|
It’s also possible to use the |
To test that Object JSON serialization and deserialization is working as expected you can use the @JsonTest
annotation. @JsonTest
will auto-configure Jackson ObjectMapper
, any @JsonComponent
beans and any Jackson Modules
. It also configures Gson
if you happen to be using that instead of, or as well as, Jackson. If you need to configure elements of the auto-configuration you can use the @AutoConfigureJsonTesters
annotation.
Spring Boot includes AssertJ based helpers that work with the JSONassert and JsonPath libraries to check that JSON is as expected. The JacksonTester
, GsonTester
and BasicJsonTester
classes can be used for Jackson, Gson and Strings respectively. Any helper fields on the test class can be @Autowired
when using @JsonTest
.
import org.junit.*;
import org.junit.runner.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.json.*;
import org.springframework.boot.test.context.*;
import org.springframework.boot.test.json.*;
import org.springframework.test.context.junit4.*;
import static org.assertj.core.api.Assertions.*;
@RunWith(SpringRunner.class)
@JsonTest
public class MyJsonTests {
@Autowired
private JacksonTester<VehicleDetails> json;
@Test
public void testSerialize() throws Exception {
VehicleDetails details = new VehicleDetails("Honda", "Civic");
// Assert against a `.json` file in the same package as the test
assertThat(this.json.write(details)).isEqualToJson("expected.json");
// Or use JSON path based assertions
assertThat(this.json.write(details)).hasJsonPathStringValue("@.make");
assertThat(this.json.write(details)).extractingJsonPathStringValue("@.make")
.isEqualTo("Honda");
}
@Test
public void testDeserialize() throws Exception {
String content = "{\"make\":\"Ford\",\"model\":\"Focus\"}";
assertThat(this.json.parse(content))
.isEqualTo(new VehicleDetails("Ford", "Focus"));
assertThat(this.json.parseObject(content).getMake()).isEqualTo("Ford");
}
}
Note | |
---|---|
JSON helper classes can also be used directly in standard unit tests. Simply call the |
A list of the auto-configuration that is enabled by @JsonTest
can be found in the appendix.
To test Spring MVC controllers are working as expected you can use the @WebMvcTest
annotation. @WebMvcTest
will auto-configure the Spring MVC infrastructure and limit scanned beans to @Controller
, @ControllerAdvice
, @JsonComponent
, Filter
, WebMvcConfigurer
and HandlerMethodArgumentResolver
. Regular @Component
beans will not be scanned when using this annotation.
Often @WebMvcTest
will be limited to a single controller and used in combination with @MockBean
to provide mock implementations for required collaborators.
@WebMvcTest
also auto-configures MockMvc
. Mock MVC offers a powerful way to quickly test MVC controllers without needing to start a full HTTP server.
Tip | |
---|---|
You can also auto-configure |
import org.junit.*;
import org.junit.runner.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.web.servlet.*;
import org.springframework.boot.test.mock.mockito.*;
import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
@RunWith(SpringRunner.class)
@WebMvcTest(UserVehicleController.class)
public class MyControllerTests {
@Autowired
private MockMvc mvc;
@MockBean
private UserVehicleService userVehicleService;
@Test
public void testExample() throws Exception {
given(this.userVehicleService.getVehicleDetails("sboot"))
.willReturn(new VehicleDetails("Honda", "Civic"));
this.mvc.perform(get("/sboot/vehicle").accept(MediaType.TEXT_PLAIN))
.andExpect(status().isOk()).andExpect(content().string("Honda Civic"));
}
}
Tip | |
---|---|
If you need to configure elements of the auto-configuration (for example when servlet filters should be applied) you can use attributes in the |
If you use HtmlUnit or Selenium, auto-configuration will also provide a WebClient
bean and/or a WebDriver
bean. Here is an example that uses HtmlUnit:
import com.gargoylesoftware.htmlunit.*;
import org.junit.*;
import org.junit.runner.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.web.servlet.*;
import org.springframework.boot.test.mock.mockito.*;
import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
@RunWith(SpringRunner.class)
@WebMvcTest(UserVehicleController.class)
public class MyHtmlUnitTests {
@Autowired
private WebClient webClient;
@MockBean
private UserVehicleService userVehicleService;
@Test
public void testExample() throws Exception {
given(this.userVehicleService.getVehicleDetails("sboot"))
.willReturn(new VehicleDetails("Honda", "Civic"));
HtmlPage page = this.webClient.getPage("/sboot/vehicle.html");
assertThat(page.getBody().getTextContent()).isEqualTo("Honda Civic");
}
}
Note | |
---|---|
By default Spring Boot will put |
A list of the auto-configuration that is enabled by @WebMvcTest
can be found in the appendix.
@DataJpaTest
can be used if you want to test JPA applications. By default it will configure an in-memory embedded database, scan for @Entity
classes and configure Spring Data JPA repositories. Regular @Component
beans will not be loaded into the ApplicationContext
.
Data JPA tests are transactional and rollback at the end of each test by default, see the relevant section in the Spring Reference Documentation for more details. If that’s not what you want, you can disable transaction management for a test or for the whole class as follows:
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
@RunWith(SpringRunner.class)
@DataJpaTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
public class ExampleNonTransactionalTests {
}
Data JPA tests may also inject a TestEntityManager
bean which provides an alternative to the standard JPA EntityManager
specifically designed for tests. If you want to use TestEntityManager
outside of @DataJpaTests
you can also use the @AutoConfigureTestEntityManager
annotation. A JdbcTemplate
is also available if you need that.
import org.junit.*;
import org.junit.runner.*;
import org.springframework.boot.test.autoconfigure.orm.jpa.*;
import static org.assertj.core.api.Assertions.*;
@RunWith(SpringRunner.class)
@DataJpaTest
public class ExampleRepositoryTests {
@Autowired
private TestEntityManager entityManager;
@Autowired
private UserRepository repository;
@Test
public void testExample() throws Exception {
this.entityManager.persist(new User("sboot", "1234"));
User user = this.repository.findByUsername("sboot");
assertThat(user.getUsername()).isEqualTo("sboot");
assertThat(user.getVin()).isEqualTo("1234");
}
}
In-memory embedded databases generally work well for tests since they are fast and don’t require any developer installation. If, however, you prefer to run tests against a real database you can use the @AutoConfigureTestDatabase
annotation:
@RunWith(SpringRunner.class)
@DataJpaTest
@AutoConfigureTestDatabase(replace=Replace.NONE)
public class ExampleRepositoryTests {
// ...
}
A list of the auto-configuration that is enabled by @DataJpaTest
can be found in the appendix.
@JdbcTest
is similar to @DataJpaTest
but for pure jdbc-related tests. By default it will also configure an in-memory embedded database and a JdbcTemplate
. Regular @Component
beans will not be loaded into the ApplicationContext
.
JDBC tests are transactional and rollback at the end of each test by default, see the relevant section in the Spring Reference Documentation for more details. If that’s not what you want, you can disable transaction management for a test or for the whole class as follows:
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.autoconfigure.jdbc.JdbcTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
@RunWith(SpringRunner.class)
@JdbcTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
public class ExampleNonTransactionalTests {
}
If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase
annotation the same way as for DataJpaTest
.
A list of the auto-configuration that is enabled by @JdbcTest
can be found in the appendix.
@DataMongoTest
can be used if you want to test MongoDB applications. By default, it will configure an in-memory embedded MongoDB (if available), configure a MongoTemplate
, scan for @Document
classes and configure Spring Data MongoDB repositories. Regular @Component
beans will not be loaded into the ApplicationContext
:
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@DataMongoTest
public class ExampleDataMongoTests {
@Autowired
private MongoTemplate mongoTemplate;
//
}
In-memory embedded MongoDB generally works well for tests since it is fast and doesn’t require any developer installation. If, however, you prefer to run tests against a real MongoDB server you should exclude the embedded MongoDB auto-configuration:
import org.junit.runner.RunWith;
import org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration;
import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@DataMongoTest(excludeAutoConfiguration = EmbeddedMongoAutoConfiguration.class)
public class ExampleDataMongoNonEmbeddedTests {
}
A list of the auto-configuration that is enabled by @DataMongoTest
can be found in the appendix.
The @RestClientTest
annotation can be used if you want to test REST clients. By default it will auto-configure Jackson and GSON support, configure a RestTemplateBuilder
and add support for MockRestServiceServer
. The specific beans that you want to test should be specified using value
or components
attribute of @RestClientTest
:
@RunWith(SpringRunner.class)
@RestClientTest(RemoteVehicleDetailsService.class)
public class ExampleRestClientTest {
@Autowired
private RemoteVehicleDetailsService service;
@Autowired
private MockRestServiceServer server;
@Test
public void getVehicleDetailsWhenResultIsSuccessShouldReturnDetails()
throws Exception {
this.server.expect(requestTo("/greet/details"))
.andRespond(withSuccess("hello", MediaType.TEXT_PLAIN));
String greeting = this.service.callRestService();
assertThat(greeting).isEqualTo("hello");
}
}
A list of the auto-configuration that is enabled by @RestClientTest
can be found in the appendix.
The @AutoConfigureRestDocs
annotation can be used if you want to use Spring REST Docs in your tests. It will automatically configure MockMvc
to use Spring REST Docs and remove the need for Spring REST Docs' JUnit rule.
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
@RunWith(SpringRunner.class)
@WebMvcTest(UserController.class)
@AutoConfigureRestDocs("target/generated-snippets")
public class UserDocumentationTests {
@Autowired
private MockMvc mvc;
@Test
public void listUsers() throws Exception {
this.mvc.perform(get("/users").accept(MediaType.TEXT_PLAIN))
.andExpect(status().isOk())
.andDo(document("list-users"));
}
}
In addition to configuring the output directory, @AutoConfigureRestDocs
can also configure the host, scheme, and port that will appear in any documented URIs. If you require more control over Spring REST Docs' configuration a RestDocsMockMvcConfigurationCustomizer
bean can be used:
@TestConfiguration
static class CustomizationConfiguration
implements RestDocsMockMvcConfigurationCustomizer {
@Override
public void customize(MockMvcRestDocumentationConfigurer configurer) {
configurer.snippets().withTemplateFormat(TemplateFormats.markdown());
}
}
If you want to make use of Spring REST Docs' support for a parameterized output directory, you can create a RestDocumentationResultHandler
bean. The auto-configuration will call alwaysDo
with this result handler, thereby causing each MockMvc
call to automatically generate the default snippets:
@TestConfiguration
static class ResultHandlerConfiguration {
@Bean
public RestDocumentationResultHandler restDocumentation() {
return MockMvcRestDocumentation.document("{method-name}");
}
}
If you’ve structured your code in a sensible way, your @SpringBootApplication
class is used by default as the configuration of your tests.
It then becomes important not to litter the application’s main class with configuration that are are specific to a particular area of its functionality.
Let’s assume that you are using Spring Batch and you’re relying on the auto-configuration for it. Your could define your @SpringBootApplication
as follows:
@SpringBootApplication
@EnableBatchProcessing
public class SampleApplication { ... }
Because this class is the source configuration for the test, any slice test will actually attempt to start Spring Batch, which is definitely not what you want to do. A recommended approach is to move that area-specific configuration to a separate @Configuration
class at the same level as your application.
@Configuration
@EnableBatchProcessing
public class BatchConfiguration { ... }
Note | |
---|---|
Depending on the surface area of your application, you may either have a single |
Another source of confusion is classpath scanning. Let’s assume that, while you’ve structured your code in a sensible way, you need to scan an additional package. Your application may look like this:
@SpringBootApplication
@ComponentScan({ "com.example.app", "org.acme.another" })
public class SampleApplication { ... }
This effectively overrides the default component scan directive with the side effect of scanning those two packages regardless of the slice that you’ve chosen. For instance a @DataJpaTest
will all of a sudden scan components and user configurations of your application. Again, moving the custom directive to a separate class is a good way to fix this issue.
Tip | |
---|---|
If this is not an option for you, you can create a |
If you wish to use Spock to test a Spring Boot application you should add a dependency on Spock’s spock-spring
module to your application’s build. spock-spring
integrates Spring’s test framework into Spock. Exactly how you can use Spock to test a Spring Boot application depends on the version of Spock that you are using.
Note | |
---|---|
Spring Boot provides dependency management for Spock 1.0. If you wish to use Spock 1.1 you should override the |
When using Spock 1.1, the annotations described above can only be used and you can annotate your Specification
with @SpringBootTest
to suit the needs of your tests.
When using Spock 1.0, @SpringBootTest
will not work for a web project. You need to use @SpringApplicationConfiguration
and @WebIntegrationTest(randomPort = true)
. Being unable to use @SpringBootTest
means that you also lose the auto-configured TestRestTemplate
bean. You can create an equivalent bean yourself using the following configuration:
@Configuration
static class TestRestTemplateConfiguration {
@Bean
public TestRestTemplate testRestTemplate(
ObjectProvider<RestTemplateBuilder> builderProvider,
Environment environment) {
RestTemplateBuilder builder = builderProvider.getIfAvailable();
TestRestTemplate template = builder == null ? new TestRestTemplate()
: new TestRestTemplate(builder.build());
template.setUriTemplateHandler(new LocalHostUriTemplateHandler(environment));
return template;
}
}
A few test utility classes are packaged as part of spring-boot
that are generally useful when testing your application.
ConfigFileApplicationContextInitializer
is an ApplicationContextInitializer
that can apply to your tests to load Spring Boot application.properties
files. You can use this when you don’t need the full features provided by @SpringBootTest
.
@ContextConfiguration(classes = Config.class,
initializers = ConfigFileApplicationContextInitializer.class)
Note | |
---|---|
Using |
EnvironmentTestUtils
allows you to quickly add properties to a ConfigurableEnvironment
or ConfigurableApplicationContext
. Simply call it with key=value
strings:
EnvironmentTestUtils.addEnvironment(env, "org=Spring", "name=Boot");
OutputCapture
is a JUnit Rule
that you can use to capture System.out
and System.err
output. Simply declare the capture as a @Rule
then use toString()
for assertions:
import org.junit.Rule;
import org.junit.Test;
import org.springframework.boot.test.rule.OutputCapture;
import static org.hamcrest.Matchers.*;
import static org.junit.Assert.*;
public class MyTest {
@Rule
public OutputCapture capture = new OutputCapture();
@Test
public void testName() throws Exception {
System.out.println("Hello World!");
assertThat(capture.toString(), containsString("World"));
}
}
TestRestTemplate
is a convenience alternative to Spring’s RestTemplate
that is useful in integration tests. You can get a vanilla template or one that sends Basic HTTP authentication (with a username and password). In either case the template will behave in a test-friendly way by not throwing exceptions on server-side errors. It is recommended, but not mandatory, to use Apache HTTP Client (version 4.3.2 or better), and if you have that on your classpath the TestRestTemplate
will respond by configuring the client appropriately. If you do use Apache’s HTTP client some additional test-friendly features will be enabled:
- Redirects will not be followed (so you can assert the response location)
- Cookies will be ignored (so the template is stateless)
TestRestTemplate
can be instantiated directly in your integration tests:
public class MyTest {
private TestRestTemplate template = new TestRestTemplate();
@Test
public void testRequest() throws Exception {
HttpHeaders headers = template.getForEntity("http://myhost.com/example", String.class).getHeaders();
assertThat(headers.getLocation().toString(), containsString("myotherhost"));
}
}
Alternatively, if you are using the @SpringBootTest
annotation with WebEnvironment.RANDOM_PORT
or WebEnvironment.DEFINED_PORT
, you can just inject a fully configured TestRestTemplate
and start using it. If necessary, additional customizations can be applied via the RestTemplateBuilder
bean. Any URLs that do not specify a host and port will automatically connect to the embedded server:
@RunWith(SpringRunner.class)
@SpringBootTest
public class MyTest {
@Autowired
private TestRestTemplate template;
@Test
public void testRequest() throws Exception {
HttpHeaders headers = template.getForEntity("/example", String.class).getHeaders();
assertThat(headers.getLocation().toString(), containsString("myotherhost"));
}
@TestConfiguration
static class Config {
@Bean
public RestTemplateBuilder restTemplateBuilder() {
return new RestTemplateBuilder()
.additionalMessageConverters(...)
.customizers(...);
}
}
}