travis-ci/travis-build — pull request #17 by gildegoma (2012-04-14 23:01:52+00:00)
Title: [Scala] By default, use Scala version configured by SBT (unless a build matrix is defined in .travis.yml)

Since Scala projects are growing on Travis, I would like to propose following changes

- major: project built with SBT that does not explicitly require a specific Scala version in .travis.yml should be built according to SBT settings (build.sbt and /project/*)
- minor: Try to make clearer that **Using Scala x.y.z** message is more an expectation, rather than a fact
- minor: remove duplicated environment variable SCALA_VERSION

### Details about the changes:

- For SBT: don't force the Scala 2.9.1 by default, but use the version
defined in SBT own settings.
- I think it's definitively better to rely on sbt settings, unless we explicitly require a build-matrix in .travis.yml.
- Since sbt can automatically download and use any Scala release (e.g. 2.9.2, 2.10.0-M2,...), it will save us the painful administration task to upgrade the default version of the travis-scala builder.
- Maybe it breaks the convention, that Travis builder always set a **default version**. In this case **undefined** means **scala-version-managed-by-build-tool-own-configuration**.
- Maybe there is a better keyword rather 'undefined', like *automatic*, *dynamic*, *unmanaged*,... (or even empty string "" ?)
- By the way, I also removed the export of SCALA_VERSION variable (duplicated by TRAVIS_SCALA_VERSION). This variable was designed before all builders were refactored to export TRAVIS_language_VERSION variable. The original variable is thus useless...