Partest is the testing framework used to regression-test the Scala compiler and standard library.

• Scala 2.11: 1.0.x
• Scala 2.12: 1.1.x
• Scala 2.13: 1.2.x

The compiler under test is instantiated by partest to compile the test files (or directories) under the test sources directory (test/files by default). The test's output is compared against the expected output specified by the corresponding .check file. Failed tests will (typically) have a log file (test/files/$kind/$testName-$kind.log) that differs from their check file (test/files/$kind/$testName.check).

Test categories (subdirectories under test/files)

• pos: these files must compile successfully
• run: in addition to compiling, Test.main is run and its output is compared against the test's .check file
• neg: these files must not compile, with compiler output matching the expected output in the .check file
• jvm: JVM-specific run tests

As partest links directly against the compiler being tested, it's cross-versioned against the compiler version that it's intended for.

Partest is invoked from sbt.

The compiler to be tested must be on the classpath. The corresponding jar or class directory is detected by FileManager::findArtifact.

The classpath to run partest is specific to the compiler/libraries under test (script not included here, but see the main test/partest script). It must provide the scala compiler to be tested and all its dependencies, and of course a compatible version of partest. For details on the available arguments, see the ConsoleRunner argument spec. Here are some non-obvious useful options:

• --failed: run only failed tests (ones that have a log file)
• --update-check: overwrite check files with log files (where the latter exists)
• -Dpartest.scalac_opts=... -> add compiler options
• -Dpartest.debug=true -> print debug messages

• tests may consist of multiple files (the test name is the directory's name), and files (including java sources) in that directory are compiled in order by looking at _$N suffixes before the file's extension and compiling them grouped by $N, in ascending order.
• jars in test/files/lib are expected to be on the classpath and may be used by tests
• certain kinds of tests (instrumented/specialized) add additional jars to the classpath

• partest.output: output directory (where classfiles go)
• partest.lib: the path of the library (jar or class dir) being tested
• partest.reflect: the path of scala-reflect (jar or class dir) being tested
• partest.comp: the path of the compiler (jar or class dir) being tested
• partest.cwd: partest working dir
• partest.test-path
• partest.testname