Prior to this commit, executing tests concurrently in the TestContext
Framework (TCF) was unsupported and typically lead to unpredictable
results.
This commit addresses this core issue by supporting concurrent
execution in the TestContextManager and the DefaultTestContext.
Specifically, the TestContextManager now uses ThreadLocal storage for
the current TestContext, thereby ensuring that any registered
TestExecutionListeners and the TestContextManager itself operate on a
TestContext specific to the current thread.
In order to avoid repeatedly incurring the costs of the overhead of the
TCF bootstrapping process, the original TestContext built by the
TestContextBootstrapper is used as a template which is then passed to
the copy constructor of the concrete implementation of the TestContext
to create the context for the current thread. DefaultTestContext now
implements such a copy constructor, and all concrete implementations of
TestContext are encouraged to do the same.
If the TestContext built by the TestContextBootstrapper does not
provide a copy constructor, thread-safety and support for concurrency
are left completely to the implementation of the concrete TestContext.
Note, however, that this commit does not address any thread-safety or
concurrency issues in the ContextLoader SPI or its implementations.
Issue: SPR-5863
a10a8e56df