Add support to query if ApplicationContext is available in the TestContext framework

[sbrannen]

Status Quo

A custom TestExecutionListener can gain access to the test's ApplicationContext via TestContext#getApplicationContext(); however, there are times when a custom TestExecutionListener would like to know if the ApplicationContext is already available (i.e., has already been successfully loaded and cached) before proceeding with a particular action.

Invoking TestContext#getApplicationContext() just to see if the ApplicationContext can be loaded is not a good option, since that will eagerly load the context, potentially resulting in negative side effects.

Proposal

Introduce support in the TestContext framework that allows a TestExecutionListener to query whether the test's ApplicationContext has already been loaded.

Related Issues

• prerequisite for Publish test execution events to the test ApplicationContext [SPR-13916] #18490

Deliverables

• Introduce boolean hasApplicationContext() in the TestContext API.
• Introduce boolean isContextLoaded(MergedContextConfiguration) in the CacheAwareContextLoaderDelegate API.