@c ========================================================================

@c Testing framework

@c ========================================================================

@unnumbered Part I:  Testing

@node TestingFramework

@chapter Testing Framework

ns-3 consists of a simulation core engine, a set of models, example programs, 

and tests.  Over time, new contributors contribute models, tests, and 

examples.  A Python test program @samp{test.py} serves as the test

execution manager; @code{test.py} can run test code and examples to

look for regressions, can output the results into a number of forms, and

can manage code coverage analysis tools.  On top of this, we layer 

@samp{Buildbots} that are automated build robots that perform

robustness testing by running the test framework on different systems

and with different configuration options.

@cartouche

Insert figure showing the components here

@end cartouche

@node BuildBots

@section Buildbots

At the highest level of ns-3 testing are the buildbots (build robots).  

If you are unfamiliar with

this system look at @uref{http://djmitche.github.com/buildbot/docs/0.7.11/}.  

This is an open-source automated system that allows @command{ns-3} to be rebuilt

and tested each time something has changed.  By running the buildbots on a number

of different systems we can ensure that @command{ns-3} builds and executes

properly on all of its supported systems.

Users (and developers) typically will not interact with the buildbot system other 

than to read its messages regarding test results.  If a failure is detected in 

one of the automated build and test jobs, the buildbot will send an email to the

@emph{ns-developers} mailing list.  This email will look something like:

@smallformat

@verbatim

  The Buildbot has detected a new failure of osx-ppc-g++-4.2 on NsNam.

  Full details are available at:

   http://ns-regression.ee.washington.edu:8010/builders/osx-ppc-g%2B%2B-4.2/builds/0

  Buildbot URL: http://ns-regression.ee.washington.edu:8010/

  Buildslave for this Build: darwin-ppc

  Build Reason: The web-page 'force build' button was pressed by 'ww': ww

  Build Source Stamp: HEAD

  Blamelist: 

  BUILD FAILED: failed shell_5 shell_6 shell_7 shell_8 shell_9 shell_10 shell_11 shell_12 

  sincerely,

  -The Buildbot

@end verbatim

@end smallformat

In the full details URL shown in the email, one can search for the keyword 

@code{failed} and select the @code{stdio} link for the corresponding step to see

the reason for the failure.

The buildbot will do its job quietly if there are no errors, and the system will

undergo build and test cycles every day to verify that all is well.

@node Testpy

@section Test.py

The buildbots use a Python program, @command{test.py}, that is reponsible for 

running all of the tests and collecting the resulting reports into a human-

readable form.  This program is also available for use by users and developers

as well.

@command{test.py} is very flexible in allowing the user to specify the number

and kind of tests to run; and also the amount and kind of output to generate.

By default, @command{test.py} will run all available tests and report status

back in a very concise form.  Running the command,

@verbatim

  ./test.py

@end verbatim

will result in a number of @code{PASS}, @code{FAIL}, @code{CRASH} or @code{SKIP}

indications followed by the kind of test that was run and its display name.

@smallformat

@verbatim

  Waf: Entering directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  'build' finished successfully (0.939s)

  FAIL: TestSuite ns3-wifi-propagation-loss-models

  PASS: TestSuite object-name-service

  PASS: TestSuite pcap-file-object

  PASS: TestSuite ns3-tcp-cwnd

  ...

  PASS: TestSuite ns3-tcp-interoperability

  PASS: Example csma-broadcast

  PASS: Example csma-multicast

@end verbatim

@end smallformat

This mode is indented to be used by users who are interested in determining if

their distribution is working correctly, and by developers who are interested

in determining if changes they have made have caused any regressions.

If one specifies an optional output style, one can generate detailed descriptions

of the tests and status.  Available styles are @command{text} and @command{HTML}.

The buildbots will select the HTML option to generate HTML test reports for the

nightly builds using,

@verbatim

  ./test.py --html=nightly.html

@end verbatim

In this case, an HTML file named ``nightly.html'' would be created with a pretty

summary of the testing done.  A ``human readable'' format is available for users

interested in the details.

@verbatim

  ./test.py --text=results.txt

@end verbatim

In the example above, the test suite checking the @command{ns-3} wireless

device propagation loss models failed.  By default no further information is

provided.

To further explore the failure, @command{test.py} allows a single test suite

to be specified.  Running the command,

@verbatim

  ./test.py --suite=ns3-wifi-propagation-loss-models

@end verbatim

results in that single test suite being run.

@verbatim

  FAIL: TestSuite ns3-wifi-propagation-loss-models

@end verbatim

To find detailed information regarding the failure, one must specify the kind

of output desired.  For example, most people will probably be interested in

a text file:

@verbatim

  ./test.py --suite=ns3-wifi-propagation-loss-models --text=results.txt

@end verbatim

This will result in that single test suite being run with the test status written to 

the file ``results.txt''.

You should find something similar to the following in that file:

@smallformat

@verbatim

FAIL: Test Suite ``ns3-wifi-propagation-loss-models'' (real 0.02 user 0.01 system 0.00)

  PASS: Test Case "Check ... Friis ... model ..." (real 0.01 user 0.00 system 0.00)

  FAIL: Test Case "Check ... Log Distance ... model" (real 0.01 user 0.01 system 0.00)

    Details:

      Message:   Got unexpected SNR value

      Condition: [long description of what actually failed]

      Actual:    176.395

      Limit:     176.407 +- 0.0005

      File:      ../src/test/ns3wifi/propagation-loss-models-test-suite.cc

      Line:      360

@end verbatim

@end smallformat

Notice that the Test Suite is composed of two Test Cases.  The first test case

checked the Friis propagation loss model and passed.  The second test case 

failed checking the Log Distance propagation model.  In this case, an SNR of

176.395 was found, and the test expected a value of 176.407 correct to three

decimal places.  The file which implemented the failing test is listed as well

as the line of code which triggered the failure.

If you desire, you could just as easily have written an HTML file using the 

@code{--html} option as described above.

Typically a user will run all tests at least once after downloading 

@command{ns-3} to ensure that his or her environment has been built correctly

and is generating correct results according to the test suites.  Developers

will typically run the test suites before and after making a change to ensure

that they have not introduced a regression with their changes.  In this case,

developers may not want to run all tests, but only a subset.  For example,

the developer might only want to run the unit tests periodically while making

changes to a repository.  In this case, @code{test.py} can be told to constrain

the types of tests being run to a particular class of tests.  The following

command will result in only the unit tests being run:

@verbatim

  ./test.py --constrain=unit

@end verbatim

Similarly, the following command will result in only the example smoke tests

being run:

@verbatim

  ./test.py --constrain=unit

@end verbatim

To see a quick list of the legal kinds of constraints, you can ask for them

to be listed.  The following command

@verbatim

  ./test.py --kinds

@end verbatim

will result in the following list being displayed:

@smallformat

@verbatim

  Waf: Entering directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  'build' finished successfully (0.939s)Waf: Entering directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  bvt:         Build Verification Tests (to see if build completed successfully)

  core:        Run all TestSuite-based tests (exclude examples)

  example:     Examples (to see if example programs run successfully)

  performance: Performance Tests (check to see if the system is as fast as expected)

  system:      System Tests (spans modules to check integration of modules)

  unit:        Unit Tests (within modules to check basic functionality)

@end verbatim

@end smallformat

Any of these kinds of test can be provided as a constraint using the @code{--constraint} 

option.

To see a quick list of all of the test suites available, you can ask for them

to be listed.  The following command,

@verbatim

  ./test.py --list

@end verbatim

will result in a list of the test suite being displayed, similar to :

@smallformat

@verbatim

  Waf: Entering directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  'build' finished successfully (0.939s)

  histogram

  ns3-wifi-interference

  ns3-tcp-cwnd

  ns3-tcp-interoperability

  sample

  devices-mesh-flame

  devices-mesh-dot11s

  devices-mesh

  ...

  object-name-service

  callback

  attributes

  config

  global-value

  command-line

  basic-random-number

  object

@end verbatim

@end smallformat

Any of these listed suites can be selected to be run by itself using the 

@code{--suite} option as shown above.

Similarly to test suites, one can run a single example program using the @code{--example}

option.

@verbatim

  ./test.py --example=udp-echo

@end verbatim

results in that single example being run.

@verbatim

  PASS: Example udp-echo

@end verbatim

Normally when example programs are executed, they write a large amount of trace 

file data.  This is normally saved to the base directory of the distribution 

(e.g., /home/user/ns-3-dev).  When @command{test.py} runs an example, it really

is completely unconcerned with the trace files.  It just wants to to determine

if the example can be built and run without error.  Since this is the case, the

trace files are written into a @code{/tmp/unchecked-traces} directory.  If you 

run the above example, you should be able to find the associated 

@code{udp-echo.tr} and @code{udp-echo-n-1.pcap} files there.

The list of available examples is defined by the contents of the ``examples''

directory in the distribution.  If you select an example for execution using

the @code{--example} option, @code{test.py} will not make any attempt to decide

if the example has been configured or not, it will just try to run it and

report the result of the attempt.

When @command{test.py} runs, by default it will first ensure that the system has

been completely built.  This can be defeated by selecting the @code{--nowaf}

option.

@verbatim

  ./test.py --list --nowaf

@end verbatim

will result in a list of the currently built test suites being displayed, similar to :

@verbatim

  ns3-wifi-propagation-loss-models

  ns3-tcp-cwnd

  ns3-tcp-interoperability

  pcap-file-object

  object-name-service

  random-number-generators

@end verbatim

Note the absence of the @command{Waf} build messages.

@code{test.py} also supports running the test suites and examples under valgrind.

Valgrind is a flexible program for debugging and profiling Linux executables.  By

default, valgrind runs a tool called memcheck, which performs a range of memory-

checking functions, including detecting accesses to uninitialised memory, misuse 

of allocated memory (double frees, access after free, etc.) and detecting memory 

leaks.  This can be selected by using the @code{--grind} option.

@verbatim

  ./test.py --grind

@end verbatim

Finally, @code{test.py} provides a @command{--verbose} option which will print

large amounts of information about its progress.  It is not expected that this

will be terribly useful unless there is an error.  In this case, you can get

access to the standard output and standard error reported by running test suites

and examples.  Select verbose in the following way:

@verbatim

  ./test.py --verbose

@end verbatim

All of these options can be mixed and matched.  For example, to run all of the 

ns-3 core test suites under valgrind, in verbose mode, while generating an HTML

output file, one would do:

@verbatim

  ./test.py --verbose --grind --constrain=core --html=results.html 

@end verbatim

@node TestTaxonomy

@section Test Taxonomy

As mentioned above, tests are grouped into a number of broadly defined 

classifications to allow users to selectively run tests to address the different

kinds of testing that need to be done.

@itemize @bullet

@item Build Verification Tests

@item Unit Tests 

@item System Tests

@item Examples

@item Performance Tests

@end itemize

@node BuildVerificationTests

@subsection Build Verification Tests

These are relatively simple tests that are built along with the distribution

and are used to make sure that the build is pretty much working.  Our

current unit tests live in the source files of the code they test and are

built into the ns-3 modules; and so fit the description of BVTs.  BVTs live

in the same source code that is built into the ns-3 code.  Our current tests

are examples of this kind of test.

@node UnitTests

@subsection Unit Tests

Unit tests are more involved tests that go into detail to make sure that a

piece of code works as advertised in isolation.  There is really no reason

for this kind of test to be built into an ns-3 module.  It turns out, for

example, that the unit tests for the object name service are about the same

size as the object name service code itself.  Unit tests are tests that

check a single bit of functionality that are not built into the ns-3 code,

but live in the same directory as the code it tests.  It is possible that

these tests check integration of multiple implementation files in a module

as well.  The file src/core/names-test-suite.cc is an example of this kind

of test.  The file src/common/pcap-file-test-suite.cc is another example

that uses a known good pcap file as a test vector file.  This file is stored

locally in the src/common directory.

@node SystemTests

@subsection System Tests

System tests are those that involve more than one module in the system.  We

have lots of this kind of test running in our current regression framework,

but they are typically overloaded examples.  We provide a new place 

for this kind of test in the directory ``src/test''.  The file

src/test/ns3tcp/ns3-interop-test-suite.cc is an example of this kind of

test.  It uses NSC TCP to test the ns-3 TCP implementation.  Often there

will be test vectors required for this kind of test, and they are stored in

the directory where the test lives.  For example,

ns3tcp-interop-response-vectors.pcap is a file consisting of a number of TCP

headers that are used as the expected responses of the ns-3 TCP under test

to a stimulus generated by the NSC TCP which is used as a ``known good''

implementation.

@node Examples

@subsection Examples

The examples are tested by the framework to make sure they built and will

run.  Nothing is checked, and currently the pcap files are just written off

into /tmp to be discarded.  If the examples run (don't crash) they pass this

smoke test.

@node PerformanceTests

@subsection Performance Tests

Performance tests are those which exercise a particular part of the system

and determine if the tests have executed to completion in a reasonable time.

@node RunningTests

@section Running Tests

Tests are typically run using the high level @code{test.py} program.  They

can also be run ``manually'' using a low level test-runner executable directly

from @code{waf}.  

@node RunningTestsUnderTestRunnerExecutable

@section Running Tests Under the Test Runner Executable

The test-runner is the bridge from generic Python code to @command{ns-3} code.

It is written in C++ and uses the automatic test discovery process in the 

@command{ns-3} code to find and allow execution of all of the various tests.

Although it may not be used directly very often, it is good to understand how

@code{test.py} actually runs the various tests.

In order to execute the test-runner, you run it like any other ns-3 executable

-- using @code{waf}.  To get a list of available options, you can type:

@verbatim

  ./waf --run "test-runner --help"

@end verbatim

You should see something like the following:

@smallformat

@verbatim

  Waf: Entering directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  Waf: Leaving directory `/home/craigdo/repos/ns-3-allinone-test/ns-3-dev/build'

  'build' finished successfully (0.353s)

  --basedir=dir:          Set the base directory (where to find src) to ``dir''

  --constrain=test-type:  Constrain checks to test suites of type ``test-type''

  --help:                 Print this message

  --kinds:                List all of the available kinds of tests

  --list:                 List all of the test suites (optionally constrained by test-type)

  --out=file-name:        Set the test status output file to ``file-name''

  --suite=suite-name:     Run the test suite named ``suite-name''

  --verbose:              Turn on messages in the run test suites

@end verbatim

@end smallformat

There are a number of things available to you which will be familiar to you if

you have looked at @command{test.py}.  This should be expected since the test-

runner is just an interface between @code{test.py} and @command{ns-3}.  You 

may notice that example-related commands are missing here.  That is because 

the examples are really not @command{ns-3} tests.  @command{test.py} runs them

as if they were to present a unified testing environment, but they are really

completely different and not to be found here.

One new option that appears here is the @code{--basedir} option.  It turns out

that the tests may need to reference the source directory of the @code{ns-3} 

distribution to find local data, so a base directory is always required to run

a test.  To run one of the tests directly from the test-runner, you will need

to specify the test suite to run along with the base directory.  So you could do,

@verbatim

  ./waf --run "test-runner --basedir=`pwd` --suite=pcap-file-object"