Runtime tests are executed via `make check' in the target/libjava/testsuite directory in the build tree. Additional runtime tests can be checked into this testsuite.
Regression testing of the core packages in libgcj is also covered by the Mauve testsuite. The Mauve Project develops tests for the Java Class Libraries. These tests are run as part of libgcj testing by placing the Mauve tree within the libjava testsuite sources at libjava/testsuite/libjava.mauve/mauve, or by specifying the location of that tree when invoking `make', as in `make MAUVEDIR=~/mauve check'.
To detect regressions, a mechanism in mauve.exp compares the failures for a test run against the list of expected failures in libjava/testsuite/libjava.mauve/xfails from the source hierarchy. Update this file when adding new failing tests to Mauve, or when fixing bugs in libgcj that had caused Mauve test failures.
We encourage developers to contribute test cases to Mauve.