Cpp Unit Testing
From SIPfoundry sipXecs IP PBX, The Open Source SIP PBX for Linux - Calivia
The CppUnit framework is used for unittesting C/C++ source code for all sipX related projects. The CppUnit Cookbook is the general guide to creating unittests but specific guidelines and information about extensions made to the CppUnit framework are described in this document.
For any given source file named src/foo/MyClass.cpp,
place unittests in a file named src/test/foo/MyClassTest.cpp.
Use the source file TestTemplate.cpp
as a template for creating all new unittests. (hint: Copy
TestTemplate.cpp to a new file called
MyClassTest.cpp then search and replace
TestTemplate with MyClassTest.)
Add your unittest to the testsuite that is run as part of the build
by listing it in the src/test/Makefile.am under the
testsuite_SOURCES make variable. (TIP: To temporarily
isolate just your unittest, remove all other source file listings from
make variable except the files in the sipxunit
directory. Alternatively you can create a separate target program with
just your unittest and source files from the sipxunit
directory, just be sure NOT to check it in that way.)
If any one unittest fails, it will stop the build from succeeding.
In scenarios where you want to check in a failed
unittest to communicate a bug beyond your control to fix, you can use
the macros KNOWN_BUG and KNOWN_FATAL_BUG to
signify such issues. This will not break the build, but will report
errors to stdout. See TestUtilities.h
header file for more information.
libtool is used to build the testsuite, consequently you must use libtool to invoke the a debugger on the testsuite. Example:
libtool --mode=execute gdb .../testsuite
where the last argument is the path to the testsuite file
in the directory containing the
testsuite-....o files generated from the tests.
Since the tests are built into shared libraries, you might not be able
to set breakpoints in them at the moment gdb starts,
since the shared libraries may not have yet been loaded. If so, use
the usual trick of break main then run to
force the executable preamble code to link in all the shared libraries.
You can also execute a subset of the tests by using the "sandbox"
feature. To use it, edit Makefile.am in the directory
containing the .o files. The sandbox_SOURCE
variable lists the tests that will be included in the subset. Rebuild
the directory (including the autoconf and
configure steps), then
run them under the debugger by doing:
libtool --mode=execute gdb .../sandbox
It is recommended each unittest be run through tools like Valgrind, Electric Fence and gcov to test for memory management and threading issues and to determine unittest code coverage. These tools will be used by automated, stress-testing machines so it's best if you use these tools ahead of time.
Valgrind
Valgrind can detect many memory management and threading bugs. See Valgrind HOWTO for more information. To run unittests under valgrind:
libtool --mode=execute valgrind --leak-check=yes -v --show-reachable=yes src/test/testsuite
Deciphering output printed to console will take some practice. You may find section "4.2.4 How to Suppress Errors" of Valgrind HOWTO helpful. Please email suggestions to dev list for ways to integrate expected leaks and errors into project.
Electric Fence
Running the unittests under Electric Fence is still
experimental, but it has been known to find some issues. Install
Electric Fence according to documentation and simply link to
memory management library like so:
./configure LDFLAGS=-lefence
Best documentation is man page man efence. If you see
Electric Fence's initialization header printed to console when running
unittests then Electric Fence is compiled in and working. Errors will
surface as segmentation faults closer to points of bad memory
management. Run unittests thru gdb or similar debugger to
further diagnose issues.
gcov
It's important to analyze the code coverage of your unittests
on the targeted source code. To compile a unittest with code
coverage analysis built in, configure the project like so:
./configure CXXFLAGS="-fprofile-arcs -ftest-coverage" make clean all check
whenever the unittests are run, coverage will be captured. To inspect coverage:
cd src
gcov {target}-MyClassName
cat MyClass.cpp.gcov
Where {target} is your library or binary
name. (hint: run ls in src directory.) Files
ending in *.gcov will be annotated listing of the source
code with the number of times each line has been executed or
##### for lines that have not been executed.
