This commit documents the new `InfoContributor` infrastructure.

Closes gh-2559

The commit adds a new BuildInfo task that can be used to generate
a build.properties file, intended for inclusion in the Actuator's
info endpoint.

A default instance of the task can be configure using the plugin's
DSL:

springBoot {
	buildInfo()
}

Additional properties can also be configured using the DSL:

springBoot {
	buildInfo {
		additionalProperties = [
			'foo': 'bar'
		]
	}
}

When configured via the DSL, the Java plugin's classes task is
configured to depend on the build info task. Alternatively, if more
control is required, the task can be declared and configured manually:

task buildInfo(type: org.springframework.boot.gradle.buildinfo.BuildInfo) {
	additionalProperties = [
		'foo': 'bar'
	]
}

classes {
	dependsOn buildInfo
}

See gh-2559

Closes gh-4901

Add a sample application that demonstrates recently added testing
features.

See gh-4901

Add @DataJpaTest and @AutoConfigureTestDatabase annotations to allow
testing of an application "slice" that only deals JPA.

See gh-4901

Add @WebMvcTest and @AutoConfigureMockMvc annotations to allow testing
of an application "slice" that only deals with Spring MVC.

See gh-4901

Add @JsonTest and @AutoConfigureJsonTesters annotations to allow testing
of an application "slice" that only deals with JSON marshalling.

See gh-4901

Provide a way for auto-configuration tests to easily filter scanned
components.

See gh-4901

Add @PropertyMapping annotation which can be used to mark annotation
attributes that should contribute Environment properties.

Provides a quick way for tests to change auto-configuration behavior in
a structured way.

Fixes gh-4901

Add a TestExecutionListener to print the auto-configuration report
when a test cannot load.

See gh-4901

Add a new test module to deal with auto-configuration in tests.

See gh-4901

Provide a way for full auto-configuration to be disabled
programmatically. Primarily added to allow special test annotations to
take over partial auto-configuration but still load
@SpringBootApplication classes.

See gh-4901

Update `@ImportAutoConfiguration` so that it can be used as a
meta-annotation. Also relocate it from the `test` package.

Fixes gh-5473

Remove the need for a nested @Configuration class when writing a test
that need to @Import configuration.

Primarily added to allow @ImportAutoConfiguration to be used directly
on test classes.

Fixes gh-5473

Add a ContextCustomizerFactory to provide TestRestTemplate as a bean for
tests annotated with WebIntegrationTests. Additionally provide support
for automatically expanding URLs of the form `/example` to
`http://localhost:${local.server.port}/example`.

Fixes gh-5227

Provide variants of `WebClient` and `WebConnectionHtmlUnitDriver` that
automatically resolve relative URLs to "localhost:${local.server.port}".

Fixes gh-5472

Add Jackson, Gson and Basic String helper classes that allow AssertJ
assertions to be used to test JSON.

Fixes gh-5471

Add a `@MockBean` annotation which can be used to setup and inject mocks
into an application context. The annotation can be used on test classes,
test fields, configuration classes or configuration fields. When used on
a field the annotation also acts as an injection point.

Fixes gh-5042

Update internal tests to drop annotations that can now
be inferred.

Fixes gh-5470

Update @IntegrationTest to use @BootstrapWith rather than an explicitly
defined set of test execution listeners.

Also introduce a new @SpringApplicationTest annotation that is similar
to  @SpringApplicationConfiguration but a bootstrapper.

Fixes gh-5230

Allow detection of `@SpringBootConfiguration` classes for both standard
spring tests and bootstrap (@IntegrationTest @WebIntegrationTest) based
tests.

Closes gh-5295

Add TestTypeExcludeFilter which will automatically attempt to exclude
test only configurations. All `@Configuration` annotated inner-classes
of tests are automatically excluded. The `@TestConfiguration` annotation
can be used to explicitly if a configuration needs explicit exclusion.

See gh-5295
See gh-4901

Add a new TypeFilter specifically for excluding candidate components.
The filter is applied to `@SpringBootApplication` and allows tests to
dynamically contribute exclude filters so that specific classes of
component can be excluded.

See gh-5295
See gh-4901

Add a new @SpringBootConfiguration annotation that can be used to
indicate the primary application configuration. The new annotation is
primarily indented to allow test automatically code to find the main
configuration class.

See gh-5295

Update SpringApplicationContextLoader to call ContextCustomizers in the
same way as other classes in `spring-test`.

Fixes gh-5294

Replace all existing SpringJUnit4ClassRunner references with the new
SpringRunner alias.

Fixes gh-5292

Update the existing tests to use the relocated `spring-boot-test`
classes. Restructuring was achieved using the following command:

find . -type f -name '*.java' -exec sed -i '' \
-e s/org.springframework.boot.test.ConfigFileApplicationContextInitializer/\
org.springframework.boot.test.context.ConfigFileApplicationContextInitializer/g \
-e s/org.springframework.boot.test.EnvironmentTestUtils/\
org.springframework.boot.test.util.EnvironmentTestUtils/g \
-e s/org.springframework.boot.test.IntegrationTest/\
org.springframework.boot.test.context.IntegrationTest/g \
-e s/org.springframework.boot.test.IntegrationTestPropertiesListener/\
org.springframework.boot.test.context.IntegrationTestPropertiesListener/g \
-e s/org.springframework.boot.test.OutputCapture/\
org.springframework.boot.test.rule.OutputCapture/g \
-e s/org.springframework.boot.test.SpringApplicationConfiguration/\
org.springframework.boot.test.context.SpringApplicationConfiguration/g \
-e s/org.springframework.boot.test.SpringApplicationContextLoader/\
org.springframework.boot.test.context.SpringApplicationContextLoader/g \
-e s/org.springframework.boot.test.SpringBootMockServletContext/\
org.springframework.boot.test.mock.web.SpringBootMockServletContext/g \
-e s/org.springframework.boot.test.TestRestTemplate/\
org.springframework.boot.test.web.client.TestRestTemplate/g \
-e s/org.springframework.boot.test.WebIntegrationTest/\
org.springframework.boot.test.context.web.WebIntegrationTest/g {} \;

See gh-5293

Create a new package structure for `spring-boot-test` and deprecate
existing classes.

Fixes gh-5293

Update spring-boot-starter-test to include JSONassert and JsonPath.
Both are generally useful libraries when writing MVC tests.

Fixes gh-5469

Update `@EnableTransactionManagement` so that `proxyTargetClass` is
set to true. This ensures that @Transactional beans that aren't
interface based can still be proxied.

Fixes gh-5423

Call afterPropertiesSet on the delegate `ResourceHttpRequestHandler`
to prevent an NPE. This change is required following SPR-13834.

This is a follow-on from the work done in 50099337. Now that SPR-14015
has been fixed, constructor injection can also be used for parameterised
dependencies, including optional dependencies that are injected via
an ObjectProvider.

Closes gh-5306

Spring Boot does not support Thymeleaf 3 yet. This commit prevents the
auto-configuration to activate if Thymeleaf 3 is available on the
classpath.

Closes gh-5371