What is DejaGnu ?

DejaGnu is a framework for testing other programs. Its purpose is to provide a single front end for all tests. Think of it as a custom library of Tcl procedures crafted to support writing a test harness. A Test Harness is the testing infrastructure that is created to support a specific program or tool. Each program can have multiple test suites, all supported by a single test harness. DejaGnu is written in Expect, which in turn uses Tcl -- Tool command language. There is more information on Tcl at the Scriptics web site, and the Expect web site is at NIST.

DejaGnu offers several advantages for testing:

• The flexibility and consistency of the DejaGnu framework make it easy to write tests for any program, with either batch oriented, or interactive programs.

• DejaGnu provides a layer of abstraction which allows you to write tests that are portable to any host or target where a program must be tested. For instance, a test for GDB can run (from any Unix based host) on any target architecture that DejaGnu supports. Currently DejaGnu runs tests on many single board computers, whose operating software ranges from just a boot monitor to a full-fledged, Unix-like realtime OS.

• All tests have the same output format. This makes it easy to integrate testing into other software development processes. DejaGnu's output is designed to be parsed by other filtering script, and it is also human readable.

• Using Tcl and expect, it's easy to create wrappers for existing test suites. By incorporating existing tests under DejaGnu, it's easier to have a single set of report analyse programs..

Running tests requires two things: the testing framework, and the test suites themselves. Tests are usually written in Expect using Tcl, but you can also use a Tcl script to run a test suite that is not based on Expect. (expect script filenames conventionally use .exp as a suffix; for example, the main implementation of the DejaGnu test driver is in the file runtest.exp.)

Julia Menapace first coined the term ``Deja Gnu'' to describe an earlier testing framework at Cygnus Support she had written for GDB. When we replaced it with the Expect-based framework, it was like DejaGnu all over again... But more importantly, it was also named after my daughter,Deja Snow Savoye (now 9 years old in Dec of 1998), who was a toddler during DejaGnu's creation.