- controller methods are static
- DB access using the framework seems to involve calling play.db.DB.getDatasource()
- Play's Cache API involves calling Cache.get(), Cache.set()
Are Play applications easy to write unit tests for? Does it involve reconfiguring the framework to use some sort of stub services rather than the real DB/Cache implementation?
FooPlugin foo = Play.current.plugin(FooPlugin.class); foo.doSomething();
What instance you get depends on configuration (typically, a play.plugins file), which makes it easy to swap out implementations at test time. Much of Play's built-in functionality is implemented as a plugin too, including the DB code, so writing unit tests is pretty simple. There is strong support for "fake applications", integration tests, etc: http://www.playframework.com/documentation/2.1.0/ScalaTest
We'll blog more about Play plugins in the future.
For Play! components, they don't hole you into one DI framework or another. Instead, you can use your favorite DI framework (or with Scala, the cake pattern) on top of any Play API calls.
Scala's language support for traits, implicit conversions, implicit parameters etc. make dependency injection trivial. Once you get used to it, things like test mocks or IOC containers seem like obvious language smells.