scala / scala-partest

Legacy repo for testing framework for Scala versions <= 2.12

Version Matrix

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

NOTE: As of Scala 2.13, Partest is back in the scala/scala repository. See the history below.


Where tests live

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

SBT usage

Historical Note

These instructions are valid as of Partest 1.0.13. Prior to that release, SBT users required scala-partest-interface in addition to scala-partest. The test framework class used to be, whereas now it is


To sbt test your project with partest through this testing interface, add something like this to your build.sbt:

libraryDependencies += "org.scala-lang.modules" %% "scala-partest" % "1.0.13" % "test" // or newer

fork in Test := true

javaOptions in Test += "-Xmx1G"

testFrameworks += new TestFramework("")

definedTests in Test += (
  new sbt.TestDefinition(
    // marker fingerprint since there are no test classes
    // to be discovered by sbt:
    new sbt.testing.AnnotatedFingerprint {
      def isModule = true
      def annotationName = "partest"
    }, true, Array())

Advanced usage:

  • 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

System properties available to tests:

  • 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