Introduce bootstrap strategy in the TestContext framework [SPR-9955]

[spring-projects-issues]

Sam Brannen opened SPR-9955 and commented

Status Quo

Work done in conjunction with #9917 and #9265 introduced physical package cycles in the spring-test module. The work performed in conjunction with #14557 uses reflection to resolve these physical package cycles; however, logical package cycles still remain.

Deliverables

1. Introduce a bootstrap strategy in the TestContext framework (TCF) that is responsible for determining and appropriately delegating to or instantiating the following:
   • AbstractDelegatingSmartContextLoader (i.e., a concrete subclass thereof)
   • MergedContextConfiguration (or a subclass thereof)
2. Refactor ContextLoaderUtils to instantiate and delegate to a bootstrap instance instead of using extensive reflection.
3. Introduce a meta-annotation that can be used to designate the concrete bootstrap strategy to use.
   • For example, @WebAppConfiguration could be annotated with such a meta-annotation that points to the web bootstrap strategy implementation.

---

Affects: 3.2 RC1

Issue Links:

• Relocate web artifacts in the TestContext framework to the web package [SPR-10067] #14700 Relocate web artifacts in the TestContext framework to the web package ("depends on")
• Deprecate TestContextManager.getDefaultTestExecutionListenerClasses() [SPR-11679] #16302 Deprecate TestContextManager.getDefaultTestExecutionListenerClasses() ("depends on")
• Deprecate support for custom, default ContextLoader class name in the TestContext framework [SPR-11682] #16305 Deprecate support for custom, default ContextLoader class name in the TestContext framework ("depends on")
• AnnotationUtils.findAnnotation() should support arbitrary levels of meta-annotations [SPR-11448] #16074 AnnotationUtils.findAnnotation() should support arbitrary levels of meta-annotations ("depends on")
• Document TestContext bootstrap strategy in the reference manual [SPR-11683] #16306 Document TestContext bootstrap strategy in the reference manual ("is depended on by")
• Enable reuse of DefaultActiveProfilesResolver [SPR-12611] #17212 Enable reuse of DefaultActiveProfilesResolver ("is depended on by")
• Provide support for session/request scoped beans for integration testing [SPR-4588] #9265 Provide support for session/request scoped beans for integration testing
• Support loading WebApplicationContexts with the TestContext Framework [SPR-5243] #9917 Support loading WebApplicationContexts with the TestContext Framework
• Fix package cycles in spring-test [SPR-9924] #14557 Fix package cycles in spring-test

Referenced from: commits b308659, a281bdb

[spring-projects-issues]

Sam Brannen commented

Completed as described in the comments for GitHub commit a281bdb:

Introduce context bootstrap strategy in the TCF

Work done in conjunction with #9917 and #9265 introduced physical
package cycles in the spring-test module. The work performed in
conjunction with #14557 uses reflection to resolve these physical
package cycles; however, prior to this commit the logical package
cycles still remain.

Furthermore, over time it has become apparent that the Spring
TestContext Framework (TCF) could better serve application developers
and especially third-party framework developers by providing a more
flexible mechanism for "bootstrapping" the TCF. For example, prior to
this commit, default TestExecutionListeners could only be registered by
subclassing TestContextManager (and SpringJUnit4ClassRunner if using
JUnit). Similarly, the default ContextLoader could only be set by
subclassing SpringJUnit4ClassRunner for JUnit and by copying and
modifying AbstractTestNGSpringContextTests for TestNG.

This commit addresses the aforementioned issues by introducing a
bootstrap strategy in the TestContext framework that is responsible for
determining default TestExecutionListeners and the default
ContextLoader in an extensible fashion. The new TestContextBootstrapper
SPI also provides a mechanism for supporting various types of
MergedContextConfiguration depending on the feature set of the context
loaders supported by the strategy.

The following provides an overview of the most significant changes in
this commit.

• Introduced TestContextBootstrapper strategy SPI, BootstrapContext,
  and @BootstrapWith.

• Introduced AbstractTestContextBootstrapper,
  DefaultTestContextBootstrapper, and WebTestContextBootstrapper
  implementations of the TestContextBootstrapper SPI and extracted
  related reflection code from ContextLoaderUtils & TestContextManager.

• Introduced BootstrapUtils for retrieving the TestContextBootstrapper
  from @BootstrapWith, falling back to a default if @BootstrapWith is
  not present.

• @WebAppConfiguration is now annotated with
  @BootstrapWith(WebTestContextBootstrapper.class).

• CacheAwareContextLoaderDelegate is now an interface with a new
  DefaultCacheAwareContextLoaderDelegate implementation class.

• Introduced closeContext(MergedContextConfiguration, HierarchyMode) in
  CacheAwareContextLoaderDelegate.

• DefaultTestContext now uses CacheAwareContextLoaderDelegate instead
  of interacting directly with the ContextCache.

• DefaultTestContext now delegates to a TestContextBootstrapper for
  building the MergedContextConfiguration.

• TestContextManager now delegates to TestContextBootstrapper for
  retrieving TestExecutionListeners.

• Deleted TestContextManager(Class, String) constructor and
  SpringJUnit4ClassRunner.getDefaultContextLoaderClassName(Class)
  method since default ContextLoader support is now implemented by
  TestContextBootstrappers.

• Extracted ActiveProfilesUtils from ContextLoaderUtils.

• Extracted ApplicationContextInitializerUtils from ContextLoaderUtils.

• MetaAnnotationUtils is now a public utility class in the test.util
  package.

• Removed restriction in @ActiveProfiles that a custom resolver cannot
  be used with the 'value' or 'profiles' attributes.

• Introduced DefaultActiveProfilesResolver.