This is a collection of tests for GDB.
The file gdb/README contains basic instructions on how to run the
testsuite, while this file documents additional options and controls
that are available. The GDB wiki may also have some pages with ideas
and suggestions.
Running the Testsuite
*********************
There are two ways to run the testsuite and pass additional parameters
to DejaGnu. The first is to do `make check' in the main build
directory and specifying the makefile variable `RUNTESTFLAGS':
make check RUNTESTFLAGS='TRANSCRIPT=y gdb.base/a2-run.exp'
The second is to cd to the testsuite directory and invoke the DejaGnu
`runtest' command directly.
cd testsuite
make site.exp
runtest TRANSCRIPT=y
(The `site.exp' file contains a handful of useful variables like host
and target triplets, and pathnames.)
Testsuite Parameters
********************
The following parameters are DejaGNU variables that you can set to
affect the testsuite run globally.
TRANSCRIPT
You may find it useful to have a transcript of the commands that the
testsuite sends to GDB, for instance if GDB crashes during the run,
and you want to reconstruct the sequence of commands.
If the DejaGNU variable TRANSCRIPT is set (to any value), each
invocation of GDB during the test run will get a transcript file
written into the DejaGNU output directory. The file will have the
name transcript.<n>, where <n> is an integer. The first line of the
file shows the invocation command with all the options passed to it,
while subsequent lines are the GDB commands. A `make check' might
look like this:
make check RUNTESTFLAGS=TRANSCRIPT=y
The transcript may not be complete, as for instance tests of command
completion may show only partial command lines.
GDB
By default, the testsuite exercises the GDB in the build directory,
but you can set GDB to be a pathname to a different version. For
instance,
make check RUNTESTFLAGS=GDB=/usr/bin/gdb
runs the testsuite on the GDB in /usr/bin.
GDBSERVER
You can set GDBSERVER to be a particular GDBserver of interest, so for
instance
make check RUNTESTFLAGS="GDB=/usr/bin/gdb GDBSERVER=/usr/bin/gdbserver"
checks both the installed GDB and GDBserver.
INTERNAL_GDBFLAGS
Command line options passed to all GDB invocations.
The default is "-nw -nx".
`-nw' disables any of the windowed interfaces.
`-nx' disables ~/.gdbinit, so that it doesn't interfere with
the tests.
This is actually considered an internal variable, and you
won't normally want to change it. However, in some situations,
this may be tweaked as a last resort if the testsuite doesn't
have direct support for the specifics of your environment.
The testsuite does not override a value provided by the user.
As an example, when testing an installed GDB that has been
configured with `--with-system-gdbinit', like by default,
you do not want ~/.gdbinit to interfere with tests, but, you
may want the system .gdbinit file loaded. As there's no way to
ask the testsuite, or GDB, to load the system gdbinit but
not ~/.gdbinit, a workaround is then to remove `-nx' from
INTERNAL_GDBFLAGS, and point $HOME at a directory without
a .gdbinit. For example:
cd testsuite
HOME=`pwd` runtest \
GDB=/usr/bin/gdb \
GDBSERVER=/usr/bin/gdbserver \
INTERNAL_GDBFLAGS=-nw
GDB_PARALLEL
When testing natively (that is, not with a remote host), you can run
the GDB test suite in a fully parallel mode. In this mode, each .exp
file runs separately and maybe simultaneously. The test suite will
ensure that all the temporary files created by the test suite do not
clash, by putting them into separate directories. This mode is
primarily intended for use by the Makefile.
To use this mode, set the GDB_PARALLEL on the runtest command line.
Before starting the tests, you must ensure that the directories cache,
outputs, and temp in the test suite build directory are either empty
or have been deleted. cache in particular is used to share data
across invocations of runtest, and files there may affect the test
results. Note that the Makefile automatically does these deletions.
GDB_INOTIFY
For debugging parallel mode, it is handy to be able to see when a test
case writes to a file outside of its designated output directory.
If you have the inotify-tools package installed, you can set the
GDB_INOTIFY variable on the runtest command line. This will cause the
test suite to watch for parallel-unsafe file creations and report
them, both to stdout and in the test suite log file.
This setting is only meaningful in conjunction with GDB_PARALLEL.
Testsuite Configuration
***********************
It is possible to adjust the behavior of the testsuite by defining
the global variables listed below, either in a `site.exp' file,
or in a board file.
gdb_test_timeout
Defining this variable changes the default timeout duration used
during communication with GDB. More specifically, the global variable
used during testing is `timeout', but this variable gets reset to
`gdb_test_timeout' at the beginning of each testcase, which ensures
that any local change to `timeout' in a testcase does not affect
subsequent testcases.
This global variable comes in handy when the debugger is slower than
normal due to the testing environment, triggering unexpected `TIMEOUT'
test failures. Examples include when testing on a remote machine, or
against a system where communications are slow.
If not specifically defined, this variable gets automatically defined
to the same value as `timeout' during the testsuite initialization.
The default value of the timeout is defined in the file
`testsuite/config/unix.exp' (at least for Unix hosts; board files may
have their own values).
Board Settings
**************
DejaGNU includes the concept of a "board file", which specifies
testing details for a particular target (which are often bare circuit
boards, thus the name).
In the GDB testsuite specifically, the board file may include a
number of "board settings" that test cases may check before deciding
whether to exercise a particular feature. For instance, a board
lacking any I/O devices, or perhaps simply having its I/O devices
not wired up, should set `noinferiorio'.
Here are the supported board settings:
gdb,cannot_call_functions
The board does not support inferior call, that is, invoking inferior
functions in GDB.
gdb,can_reverse
The board supports reverse execution.
gdb,no_hardware_watchpoints
The board does not support hardware watchpoints.
gdb,nofileio
GDB is unable to intercept target file operations in remote and
perform them on the host.
gdb,noinferiorio
The board is unable to provide I/O capability to the inferior.
gdb,noresults
A program will not return an exit code or result code (or the value
of the result is undefined, and should not be looked at).
gdb,nosignals
The board does not support signals.
gdb,skip_huge_test
Skip time-consuming tests on the board with slow connection.
gdb,skip_float_tests
Skip tests related to floating point.
gdb,use_precord
The board supports process record.
gdb_server_prog
The location of GDBserver. If GDBserver somewhere other than its
default location is used in test, specify the location of GDBserver in
this variable. The location is a file name for GDBserver, and may be
either absolute or relative to the testsuite subdirectory of the build
directory.
in_proc_agent
The location of the in-process agent (used for fast tracepoints and
other special tests). If the in-process agent of interest is anywhere
other than its default location, set this variable. The location is a
filename, and may be either absolute or relative to the testsuite
subdirectory of the build directory.
noargs
GDB does not support argument passing for inferior.
no_long_long
The board does not support type long long.
use_cygmon
The board is running the monitor Cygmon.
use_gdb_stub
The tests are running with a GDB stub.
exit_is_reliable
Set to true if GDB can assume that letting the program run to end
reliably results in program exits being reported as such, as opposed
to, e.g., the program ending in an infinite loop or the board
crashing/resetting. If not set, this defaults to $use_gdb_stub. In
other words, native targets are assumed reliable by default, and
remote stubs assumed unreliable.
gdb,predefined_tsv
The predefined trace state variables the board has.
Testsuite Organization
**********************
The testsuite is entirely contained in `gdb/testsuite'. The main
directory of the testsuite includes some makefiles and configury, but
these are 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 directories named
'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 typically get chosen and run in alphabetical order.
The following lists some notable 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.
gdb.base
This is the base testsuite. The tests in it should apply to all
configurations of GDB (but generic native-only tests may live here).
The test programs should be in the subset of C that is both valid
ANSI/ISO C, and C++.
gdb.<lang>
Language-specific tests for any language besides C. Examples are
gdb.cp for C++ and gdb.java for Java.
gdb.<platform>
Non-portable tests. The tests are specific to a specific
configuration (host or target), such as HP-UX or eCos. Example is
gdb.hp, for HP-UX.
gdb.arch
Architecture-specific tests that are (usually) cross-platform.
gdb.<subsystem>
Tests that exercise a specific GDB subsystem in more depth. For
instance, gdb.disasm exercises various disassemblers, while
gdb.stabs tests pathways through the stabs symbol reader.
Writing Tests
*************
In many areas, the GDB tests are already quite comprehensive; you
should be able to copy existing tests to handle new cases. Be aware
that older tests may use obsolete practices but have not yet been
updated.
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. Even
if GDB has several valid responses to a command, you can use
`gdb_test_multiple'. Like `gdb_test', `gdb_test_multiple' recognizes
internal errors and unexpected prompts.
Do not write tests which expect a literal tab character from GDB. On
some operating systems (e.g. OpenBSD) the TTY layer expands tabs to
spaces, so by the time GDB's output reaches `expect' the tab is gone.
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 might
never manifest themselves if the test programs used GNU coding style
uniformly.
Some testcase results need more detailed explanation:
KFAIL
Use KFAIL for known problem of GDB itself. You must specify the GDB
bug report number, as in these sample tests:
kfail "gdb/13392" "continue to marker 2"
or
setup_kfail gdb/13392 "*-*-*"
kfail "continue to marker 2"
XFAIL
Short for "expected failure", this indicates a known problem with the
environment. This could include limitations of the operating system,
compiler version, and other components.
This example from gdb.base/attach-pie-misread.exp is a sanity check
for the target environment:
# On x86_64 it is commonly about 4MB.
if {$stub_size > 25000000} {
xfail "stub size $stub_size is too large"
return
}
You should provide bug report number for the failing component of the
environment, if such bug report is available, as with this example
referring to a GCC problem:
if {[test_compiler_info {gcc-[0-3]-*}]
|| [test_compiler_info {gcc-4-[0-5]-*}]} {
setup_xfail "gcc/46955" *-*-*
}
gdb_test "python print ttype.template_argument(2)" "&C::c"
Note that it is also acceptable, and often preferable, to avoid
running the test at all. This is the better option if the limitation
is intrinsic to the environment, rather than a bug expected to be
fixed in the near future.
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