The testsuite is an important component of the GDB package. While it is always worthwhile to encourage user testing, in practice this is rarely sufficient; users typically use only a small subset of the available commands, and it has proven all too common for a change to cause a significant regression that went unnoticed for some time.
The GDB testsuite uses the DejaGNU testing framework.
DejaGNU is built using Tcl and expect. The tests
themselves are calls to various Tcl procs; the framework runs all the
procs and summarizes the passes and fails.
To run the testsuite, simply go to the GDB object directory (or to the
testsuite's objdir) and type make check. This just sets up some
environment variables and invokes DejaGNU's runtest script. While
the testsuite is running, you'll get mentions of which test file is in use,
and a mention of any unexpected passes or fails. When the testsuite is
finished, you'll get a summary that looks like this:
=== gdb Summary ===
# of expected passes 6016
# of unexpected failures 58
# of unexpected successes 5
# of expected failures 183
# of unresolved testcases 3
# of untested testcases 5
The ideal test run consists of expected passes only; however, reality conspires to keep us from this ideal. Unexpected failures indicate real problems, whether in GDB or in the testsuite. Expected failures are still failures, but ones which have been decided are too hard to deal with at the time; for instance, a test case might work everywhere except on AIX, and there is no prospect of the AIX case being fixed in the near future. Expected failures should not be added lightly, since you may be masking serious bugs in GDB. Unexpected successes are expected fails that are passing for some reason, while unresolved and untested cases often indicate some minor catastrophe, such as the compiler being unable to deal with a test program.
When making any significant change to GDB, you should run the testsuite before and after the change, to confirm that there are no regressions. Note that truly complete testing would require that you run the testsuite with all supported configurations and a variety of compilers; however this is more than really necessary. In many cases testing with a single configuration is sufficient. Other useful options are to test one big-endian (Sparc) and one little-endian (x86) host, a cross config with a builtin simulator (powerpc-eabi, mips-elf), or a 64-bit host (Alpha).
If you add new functionality to GDB, please consider adding tests for it as well; this way future GDB hackers can detect and fix their changes that break the functionality you added. Similarly, if you fix a bug that was not previously reported as a test failure, please add a test case for it. Some cases are extremely difficult to test, such as code that handles host OS failures or bugs in particular versions of compilers, and it's OK not to try to write tests for all of those.
DejaGNU supports separate build, host, and target machines. However, some GDB test scripts do not work if the build machine and the host machine are not the same. In such an environment, these scripts will give a result of "UNRESOLVED", like this:
UNRESOLVED: gdb.base/example.exp: This test script does not work on a remote host.
The testsuite is entirely contained in `gdb/testsuite'. While the
testsuite includes some makefiles and configury, these are very minimal,
and used for little besides cleaning up, since the tests themselves
handle the compilation of the programs that GDB will run. The file
`testsuite/lib/gdb.exp' contains common utility procs useful for
all GDB tests, while the directory `testsuite/config' contains
configuration-specific files, typically used for special-purpose
definitions of procs like gdb_load and gdb_start.
The tests themselves are to be found in `testsuite/gdb.*' and subdirectories of those. The names of the test files must always end with `.exp'. DejaGNU collects the test files by wildcarding in the test directories, so both subdirectories and individual files get chosen and run in alphabetical order.
The following table lists the main types of subdirectories and what they are for. Since DejaGNU finds test files no matter where they are located, and since each test file sets up its own compilation and execution environment, this organization is simply for convenience and intelligibility.
#ifdefs are allowed if necessary, for instance
for prototypes).
In many areas, the GDB tests are already quite comprehensive; you should be able to copy existing tests to handle new cases.
You should try to use gdb_test whenever possible, since it
includes cases to handle all the unexpected errors that might happen.
However, it doesn't cost anything to add new test procedures; for
instance, `gdb.base/exprs.exp' defines a test_expr that
calls gdb_test multiple times.
Only use send_gdb and gdb_expect when absolutely
necessary, such as when GDB has several valid responses to a command.
The source language programs do not need to be in a consistent style. Since GDB is used to debug programs written in many different styles, it's worth having a mix of styles in the testsuite; for instance, some GDB bugs involving the display of source lines would never manifest themselves if the programs used GNU coding style uniformly.
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