Tuesday, June 25, 2013

Using GNU autotest for running unit tests

This is part of a series of blog posts about testing inside the OpenBSC/Osmocom project. In this post I am focusing on our usage of GNU autotest.

The GNU autoconf ships with a not well known piece of software. It is called GNU autotest and we will focus about it in this blog post.

GNU autotest is a very simple framework/test runner. One needs to define a testsuite and this testsuite will launch test applications and record the exit code, stdout and stderr of the test application. It can diff the output with expected one and fail if it is not matching. Like any of the GNU autotools a log file is kept about the execution of each test. This tool can be nicely integrated with automake's make check and make distcheck. This will execute the testsuite and in case of a test failure fail the build.

The way we use it is also quite simple as well. We create a simple application inside the test/testname directory and most of the time just capture the output on stdout. Currently no unit-testing framework is used, instead a simple application is built that is mostly using OSMO_ASSERT to assert the expectations. In case of a failure the application will abort and print a backtrace. This means that in case of a failure the stdout will not not be as expected and the exit code will be wrong as well and the testcase will be marked as FAILED.

The following will go through the details of enabling autotest in a project.

Enabling GNU autotest

The file needs to get a line like this: AC_CONFIG_TESTDIR(tests). It needs to be put after the AC_INIT and AM_INIT_AUTOMAKE directives and make sure AC_OUTPUT lists tests/atlocal

Integrating with the automake

The next thing is to define a testsuite inside the tests/ This is some boilerplate code that creates the testsuite and makes sure it is invoked as part of the build process.

 # The `:;' works around a Bash 3.2 bug when the output is not writeable.  
 $(srcdir)/package.m4: $(top_srcdir)/  
  :;{ \  
         echo '# Signature of the current package.' && \  
         echo 'm4_define([AT_PACKAGE_NAME],' && \  
         echo ' [$(PACKAGE_NAME)])' &&; \  
         echo 'm4_define([AT_PACKAGE_TARNAME],' && \  
         echo ' [$(PACKAGE_TARNAME)])' && \  
         echo 'm4_define([AT_PACKAGE_VERSION],' && \  
         echo ' [$(PACKAGE_VERSION)])' && \  
         echo 'm4_define([AT_PACKAGE_STRING],' && \  
         echo ' [$(PACKAGE_STRING)])' && \  
         echo 'm4_define([AT_PACKAGE_BUGREPORT],' && \  
         echo ' [$(PACKAGE_BUGREPORT)])'; \  
         echo 'm4_define([AT_PACKAGE_URL],' && \  
         echo ' [$(PACKAGE_URL)])'; \  
        } &>'$(srcdir)/package.m4'  
 EXTRA_DIST = $(srcdir)/package.m4 $(TESTSUITE)  
 TESTSUITE = $(srcdir)/testsuite  
 DISTCLEANFILES = atconfig  
 check-local: atconfig $(TESTSUITE)  
 installcheck-local: atconfig $(TESTSUITE)  
  $(SHELL) '$(TESTSUITE)' AUTOTEST_PATH='$(bindir)' \  
  test ! -f '$(TESTSUITE)' || \  
  $(SHELL) '$(TESTSUITE)' --clean  
 AUTOM4TE = $(SHELL) $(top_srcdir)/missing --run autom4te  
 AUTOTEST = $(AUTOM4TE) --language=autotest  
 $(TESTSUITE): $(srcdir)/ $(srcdir)/package.m4  
  $(AUTOTEST) -I '$(srcdir)' -o $@.tmp $  
  mv $@.tmp $@  

Defining a testsuite

The next part is to define which tests will be executed. One needs to create a file with content like the one below:

 AT_BANNER([Regression tests.])  
 cat $abs_srcdir/gsm0408/gsm0408_test.ok > expout  
 AT_CHECK([$abs_top_builddir/tests/gsm0408/gsm0408_test], [], [expout], [ignore])  

This will initialize the testsuite, create a banner. The lines between AT_SETUP and AT_CLEANUP represent one testcase. In there we are copying the expected output from the source directory into a file called expout and then inside the AT_CHECK directive we specify what to execute and what to do with the output.

Executing a testsuite and dealing with failure

The testsuite will be automatically executed as part of make check and make distcheck. It can also be manually executed by entering the test directory and executing the following.

 $ make testsuite  
 make: `testsuite' is up to date.  
 $ ./testsuite  
 ## ---------------------------------- ##  
 ## openbsc test suite. ##  
 ## ---------------------------------- ##  
 Regression tests.  
  1: gsm0408                     ok  
  2: db                       ok  
  3: channel                     ok  
  4: mgcp                      ok  
  5: gprs                      ok  
  6: bsc-nat                     ok  
  7: bsc-nat-trie                  ok  
  8: si                       ok  
  9: abis                      ok  
 ## ------------- ##  
 ## Test results. ##  
 ## ------------- ##  
 All 9 tests were successful.  

In case of a failure the following information will be printed and can be inspected to understand why things went wrong.

  2: db                       FAILED (  
 ## ------------- ##  
 ## Test results. ##  
 ## ------------- ##  
 ERROR: All 9 tests were run,  
 1 failed unexpectedly.  
 ## -------------------------- ##  
 ## testsuite.log was created. ##  
 ## -------------------------- ##  
 Please send `tests/testsuite.log' and all information you think might help:  
   Subject: [openbsc] testsuite: 2 failed  
 You may investigate any problem if you feel able to do so, in which  
 case the test suite provides a good starting point. Its output may  
 be found below `tests/testsuite.dir'.  

You can go to tests/testsuite.dir and have a look at the failing tests. For each failing test there will be one directory that contains a log file about the run and the output of the application. We are using GNU autotest in libosmocore, libosmo-abis, libosmo-sccp, OpenBSC, osmo-bts and cellmgr_ng.

1 comment:

Allan "Goldfish" Clark said...

one typo: you comment that one should have tests/atlocal in AC_FILES, yet your included uses tests/atconfig which is provided for you in autoconf now.

It might need some clarification, and a working example. you might have scraped together two disagreeing documents.