Improve documentation of the context caching mechanism in the TestContext framework [SPR-7996]

[spring-projects-issues]

Caleb Jones opened SPR-7996 and commented

Overview

Unit/integration test execution libraries can sometimes be configured to execute tests in a forked manner (see surefire's forkMode configuration). When tests are run in a forked mode, in-memory @ContextConfiguration caching no longer applies, and the context will be reloaded for every forked process.

The Spring reference manual merely states that @ContextConfiguration is cached and does not go into much detail beyond that. I think it would be good to specify that the cache is in-memory and thus will only be usable for tests which run within the same JVM process / class space. Perhaps a Spring note (the ones with the little leaf icon and block quote styling) would be good to call this out in the Testing chapter.

To Document

• cache key generation, including a discussion of the algorithm in MergedContextConfiguration
• cache scope and implications in a test suite, including a discussion of forking

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Affects: 2.5.6, 3.0.5

Reference URL: http://forum.springsource.org/showthread.php?t=104164

Issue Links:

• TestContext should generate cache keys based on all metadata that uniquely identify ApplicationContext configuration [SPR-7326] #11984 TestContext should generate cache keys based on all metadata that uniquely identify ApplicationContext configuration
• ContextCache should be keyed by MergedContextConfiguration instead of String [SPR-8549] #13193 ContextCache should be keyed by MergedContextConfiguration instead of String

Referenced from: commits e90c7ea

[spring-projects-issues]

Caleb Jones commented

Link to surefire's forkMode had a trailing quotation mark which invalidates the URL's anchor.

Correct URL is:
http://maven.apache.org/plugins/maven-surefire-plugin/test-mojo.html#forkMode

[spring-projects-issues]

Caleb Jones commented

May also be good to note that for a fairly sizable number of test classes using @ContextConfiguration, forking each in its own process will result in very long test execution times since (again) the context must be re-created for each test class.

See forum comments for more details.

[spring-projects-issues]

Sam Brannen commented

Improved documentation of the context caching mechanism in the TestContext framework:

• now discussing cache key generation and uniqueness
• now discussing cache scope, test suites, and forking