Developing the CODESYS runtime with TDD

Introduction

 

I was recently working in the CODESYS runtime again, developing some components for a client and I thought the experience wold make the basis of a good post on bringing legacy code into a test environment, to enable Test Driven Development (TDD)

The CODESYS runtime is a component based system, and for most device manufacturers is delivered as a binary for their target system and a collection of header files and interface definitions. Much of the interface is generic, however there are platform specific headers that abstract the underlying RTOS. Device manufacturers often develop bespoke runtime components, to access proprietary IO for example. To help with this the delivered software package includes template components as a starting point for development. This means that, according to Michael Feathers definition of legacy code (code without tests), the starting point when developing a CODESYS component is legacy code. In this example the starting point was a partially developed component, legacy code.

 

The Plan

I tend to follow a fairly standard process when bringing legacy code under test. The basic process is well described in TDD How-to: Get your legacy C into a test harness on James Grenning’s blog.  I follow roughly the same process, with minor changes, my process can be summarised as follows

  • Select appropriate tools
  • Create a test harness with no reference to the code to be tested and a dummy failing test. Observe it fail. Fix the test and observe it pass.
  • Decide the boundaries of the code I want to test, and include this source in the test harness build.
  • Make the test harness compile (not link)
  • Make the code Link using exploding fakes.
  • Ensure the dummy test still passes
  • Add the first test of the code under test (expect it to crash or fail)
  • Make the test pass by adding initialisation, and using better fakes.
  • Add more tests, always observe them fail (force a failure if needs be – to check that the error output is meaningful), factor out common code into helper functions. Keep the tests small and testing one thing.
  • Add profiling, I like to be able to observe which parts of the code are under test before I make any changes. Particularly if the code under test has large complex functions it is the only way that I trust I have sufficient coverage before making code changes.

Tools

The development build of the component uses a gcc cross compiler on linux. The build is controlled by a makefile and there is already an eclipse project.

I will use the native gcc compiler to run the tests

For the testing framework I’m using googletest 1.8, my preferred test framework for C and C++

To help with creating fakes and mocks I will use Mike Long’s Fake Function Framework (fff).

I will add plugins to eclipse so that the whole process can happen in a single environment.

 

The first test

There are two ways of using googletest, one is to build it as a library and link it to the tests, the other is to fuse the source into a single file, and then include the fused source in the tests. On linux I tend to just build the library with default settings.

I’ve created a new folder called UnitTests to which I’ve added a makefile and a single source file with this content

#include "gtest/gtest.h"
namespace 
{
TEST(FirstTest, ShouldPass)
{
ASSERT_EQ(1,0);
}
} // namespace

The makefile, references just this source file, the include path has the path to googletest/include. The link line is shown below (I’ve omitted the paths for simplicity)

g++ FirstTest.o gtest_main.a -lpthread -o UnitTest

This builds, and when run fails as below

screen-shot-2016-09-08-at-11-06-57

Change the the ASSERT_EQ so that the test passes, rebuild and re-run the tests.

Compiling with the UUT

The CODESYS component that that I’m working on consists of a single source file (The Unit Under Test UUT), and it links into a target specific library

To get the test application to compile I had to add three directories to the include path

-I$(CODESYS)/Components
-I$(CODESYS)/Platforms/Linux
-I$(TARGET_LIB_SRC)/include

NOTE: If the CODESYS runtime delivery is for a different operating system to the development system then it may be necessary to create fake versions of the headers in the Platforms directory. It may also be necessary to fake some of the RTOS header files.

Linking – Exploding Fakes

Having resolved the includes there are lots of unresolved symbols. A good starting point is to generate a file of exploding fakes, the idea here is to ensure that you know when you are faking code. Have a look at James’ exploding fake generator, this can easily be adapted to any linker and any test framework. Save the output of your failed link into a file, execute gen-exploding-fakes-from-linker-output.sh to generate a file of exploding fakes which you include into your build.

make >& make.out
gen-exploding-fakes-from-linker-output.sh make.out explodingfake.c

The only other change required is to copy explodingfakes.h somewhere on the include path for the tests and adapt it to work with gtest as shown.

#ifndef EXPLODING_FAKE_INCLUDED
#define EXPLODING_FAKE_INCLUDED
#include "gtest/gtest.h"
#define EXPLODING_FAKE_FOR(f) void f() { FAIL() << "go write a proper stub for " #f; }
#endif

Now the test application should run and pass again, none of the UUT is yet being executed.

 

Testing – Part 1

CODESYS components have well defined interfaces, and I find it pays to test from those interfaces rather then exposing internals of the component wherever possible. Taking this approach tends to lead to less fragile tests that are testing the functionality rather than the implementation.

All components implement CmpItf, an interface that allows the component to be registered and initialised. CmpItf requires a single extern function ComponentEntry to be declared, all other functions in the interface are accessed through function pointers returned by this function call. So my starting point is to write tests that test this interface.

The first tests are straight forward, and soon the ComponentEntry call itself is factored out into the test constructor.

#include "gtest/gtest.h"
extern "C"
{
#include "CmpMyComponentDep.h"
DLL_DECL RTS_INT CDECL ComponentEntry(INIT_STRUCT *pInitStruct);
}
namespace
{
class CmpItfTest: public ::testing::Test
{
public:
CmpItfTest():m_rResult(ERR_OK),m_InitStruct()
{
m_rResult = ComponentEntry(&m_InitStruct);
}
RTS_RESULT m_rResult;
INIT_STRUCT m_InitStruct;
};
TEST_F(CmpItfTest, ComponentEntryShouldSucceed)
{
ASSERT_EQ(ERR_OK, m_rResult);
}
TEST_F(CmpItfTest, ComponentEntryShouldSetComponentID)
{
ASSERT_EQ(0x166B2002, m_InitStruct.CmpId);
}
TEST_F(CmpItfTest, CmpGetVersionShouldReturnCorrectVersion)
{
ASSERT_EQ(0x03050800, m_InitStruct.pfGetVersion());
}

Fairly soon I am testing code that calls into other CODESYS components, as soon as I do, the exploding fakes show up in the tests.

screen-shot-2016-09-11-at-08-53-13

 

Using The Fake Function Framework

Now I need a more powerful fake, this is where the fake function framework comes in to it’s own. Creating a fake for EventOpen can be as simple as adding the following to the test source file, and making sure fff.h is on the include path

#include "fff.h"
#include "CmpEventMgrItf.h"
DEFINE_FFF_GLOBALS;
FAKE_VALUE_FUNC( RTS_HANDLE, EventOpen , EVENTID , CMPID , RTS_RESULT *);

Having added this the link will fail with a message like

CmpEventMgrItf.fff.c:7: multiple definition of `EventOpen'

Remove the line from explodingfakes.c for EventOpen, and the tests should now run again.

It is then possible to write a simple test to prove that the EventOpen function has been called.

TEST_F(CmpItfTest, HookCH_INIT3ShouldOpenEvent)
{
m_InitStruct.pfHookFunction(CH_INIT3,0,0);
    ASSERT_EQ(1, EventOpen_fake.call_count);
}

The Fake Function Framework includes facilities for recording a history of argument calls, setting return values and the ability to provide a custom fake. It makes a very powerful tool for testing C code, I’m not going to cover all of the features here there are plenty of other examples on the web. Do note though that fakes need to be reset for each new test. The constructor for my test fixture looks like this

CmpItfTest():m_rResult(ERR_OK),m_InitStruct()
{
    m_rResult = ComponentEntry(&m_InitStruct);
RESET_FAKE(EventOpen);
FFF_RESET_HISTORY();
}

As tests grow and there become multiple test files using the same fakes it makes sense to pull the fakes out into separate files,. I follow a pattern, if I am faking functions defined in a file called XXX.h, I create XXX.fff.h and XXX.fff.c and define my fakes in these files. Most of the time I take the approach of generating each fake manually, one by one as required.

CODESYS specifies the interface to all components in .m4 files, in the delivery I have there are 164 interface files specified. I know that over time these interfaces will be extended, and more interfaces added. I have generated a tool to process the interface definitions and automatically generate fff fakes for each API function in each of the interfaces. I then build these fakes into a static library that can be linked with any component I develop.

There is a danger in automating fake generation, it becomes very easy to not realise when you are using a fake. Most API functions in CODESYS return an RTS_RESULT, ERR_OK means success. ERR_OK has the value of zero which is also the default value returned by fff fakes. If developing new code this isn’t a problem. But when bringing a legacy component under test it can lead to code appearing to be tested when it isn’t. This can be avoided by still using exploding fakes within fff.

To achieve all of this using the test library all I need in the tests is an include of the appropriate fake header file,

#include “CmpEventMgrItf.fff.h”

and the test constructor is changed to reset all of the CmpEventMgrItf fakes, set all of the fakes to explode, and then for the two functions that I want to fake I can disable the exploding behaviour.

CmpItfTest():m_rResult(ERR_OK),m_InitStruct()
{
    m_rResult = ComponentEntry(&m_InitStruct);
FFF_CmpEventMgrItf_FAKES_LIST(RESET_FAKE);
FFF_RESET_HISTORY();
    FFF_CmpEventMgrItf_FAKES_LIST(FFF_EXPLODE);
// Allow normal fake operation for these functions, all others in the interface will explode if called.
EventOpen_fake.custom_fake = NULL; 
EventRegisterCallbackFunction_fake.custom_fake = NULL;
}

What does the fakes library look like?

To show what is included in the library of fakes, for those who are interested below is the content of the CmpEventMgrItf fakes cut down to show just the two functions that have been used.

CmpEventMgrItf.fff.h

#ifndef __CmpEventMgrItf__FFF_H__
#define __CmpEventMgrItf__FFF_H__
#include "fff.h"
#include <string.h>
#include "fff_explode.h"
#include "CmpEventMgrItf.h"
DECLARE_FAKE_VALUE_FUNC3( RTS_HANDLE, EventOpen , EVENTID , CMPID , RTS_RESULT * );
DECLARE_FAKE_VALUE_FUNC2( RTS_RESULT, EventRegisterCallback , RTS_HANDLE , ICmpEventCallback * );
RTS_HANDLE EventOpen_explode( EVENTID , CMPID , RTS_RESULT * );
RTS_RESULT EventRegisterCallback_explode( RTS_HANDLE , ICmpEventCallback * );
#define FFF_CmpEventMgrItf_FAKES_LIST(FAKE) 
FAKE(EventOpen)
FAKE(EventRegisterCallback)
#endif /* __CmpEventMgrItf__FFF_H__ */

Other than including headers three things are happening in this file. Firstly the fff fakes are declared, secondly prototypes for exploding functions are declared and finally a list of all faked functions is created allowing operations to be done on all fakes in one statement.

CmpEventMgrItf.fff.cpp

#include "CmpEventMgrItf.fff.h"
DEFINE_FAKE_VALUE_FUNC3( RTS_HANDLE, EventOpen , EVENTID , CMPID , RTS_RESULT * );
DEFINE_FAKE_VALUE_FUNC2( RTS_RESULT, EventRegisterCallback , RTS_HANDLE , ICmpEventCallback * );
RTS_HANDLE EventOpen_explode( EVENTID  a, CMPID  b, RTS_RESULT * z ){ fff_explode("EventOpen"); return (RTS_HANDLE)0; }
RTS_RESULT EventRegisterCallback_explode( RTS_HANDLE  a, ICmpEventCallback * z ){ fff_explode("EventRegisterCallback"); return (RTS_RESULT)0; }

The fff fakes are defined along with definitions of the exploding fakes. Each exploding fake calls fff_explode, which is declared in a separate module allowing the way it explodes to be changed for a different testing tool..

fff_explode.h

#ifndef __FFF_EXPLODE_H__
#define __FFF_EXPLODE_H__
#define FFF_EXPLODE(a) a##_fake.custom_fake = a##_explode;
#ifdef __cplusplus
extern "C"
{
#endif
void fff_explode(const char * func);
#ifdef __cplusplus
}
#endif
#endif /* __FFF_EXPLODE_H__ */

The macro FFF_EXPLODE(a)  sets the custom_fake variable in an fff fake to point to the exploding fake.

fff_explode.cpp

#include "fff_explode.h"
#include "gtest/gtest.h"
#ifdef __cplusplus
extern "C"
{
#endif
void fff_explode(const char * func)
{
    FAIL()<<"Time to use fake for "<<func;
}
#ifdef __cplusplus
}
#endif

Keeping it fast

As I mentioned in the tools section the production code is being built in eclipse. I want to build the test code in eclipse as well, and I want everything to work seamlessly.

I added a second Build Configuration to the production code build, and made this build the unit tests. Having done this I want to run the tests every time I build (Or rather I want to run the tests after every code change, and have the code rebuilt if required). This requires an optional component to be installed in eclipse. Go to Help->Install New Software…, choose to Work with: –All Available Sites– and then under Programming Languages select C/C++ Unit Testing Support, click Next>, Next>, Finish and wait for the install to complete. Restart eclipse when prompted.

Now right click on your project in eclipse and selectRun As->Run Configurations... Create a new C/C++ Unit Test configuration. Use Search Project to find your Unit Test application, then on the C/C++ Testing tab, select Google Tests Runner.

screen-shot-2016-09-08-at-16-14-25

When you run this configuration, it should force your tests to be built and then display the results graphically. Clicking on any failures will take you to the failing tests.

screen-shot-2016-09-10-at-13-20-46

Profiling

Particularly when bringing legacy code under test, I like to be able to visualise what is being tested and what isn’t. If you are using gcc then this becomes very easy.

Add these compiler flags to the compilation of the unit under test, and to the link line.

-fprofile-arcs -ftest-coverage

Building and then running with profiling generates .gcda and .gcno files, these are specific to a particular build, so to ensure there are no mismatches in versions add to the link rule in the makefile an action to remove all .gcda and .gcno files from the object directory.

Now having run your tests look in the object directory in eclipse and you will see .gcda and .gcno files, double click one of them. In the dialog that pops up, ensure that your unit test executable is selected, and choose “Show coverage for the whole selected binary“.

For me the key is not the amount of code covered, much more, what has been covered by my tests. Each file can be inspected and it is very clear what was run by the tests and what wasn’t. This helps me decide if I have sufficient coverage before making changes. For example, the bars below show that my tests don’t cover all of the initialisation functions.

screen-shot-2016-09-10-at-13-30-15

ExportFunctions is a standard function that is part of all components, the implementation shouldn’t change. The image below shows that the test suite invokes it, but there must be a return statement inside the EXPORT_STMT. Without code coverage I may never have known that some of the code wasn’t being exercised. Inspecting the code will then tell me if I need to add tests or not. This may be a trivial example but I hope it shows why inspecting test coverage helps you understand what is being tested. You can then make informed decisions about increasing the coverage, or accepting that you have gone far enough.

screen-shot-2016-09-10-at-13-30-46

Once I’m happy with the coverage in an area I want to change I can start more traditional TDD development. Having started TDD, I tend not to use code coverage checks very often. Being rigorous about TDD tends to lead to 100% coverage, the main time I re-use the coverage checks is if I have refactored the UUT, it helps to show not just that the existing functionality still passes, but that I haven’t inadvertently added some untested functionality.

Summary and next steps

Investing the time to get the component under test has given me a re-useable test harness that allows me to extend and refactor the code with confidence. Future development can happen much faster than it would otherwise, as much of the functionality can be proven before taking the software anywhere near the embedded target.

Some components it is worth investing the time to create pre-canned functionality through custom_fakes. Consider these components

SysMem

With no further work fff can be used to simulate failures, check the sizes being allocated and return fixed data structures on allocations. However in some tests we just want the memory allocation to work, so having a simple set of custom fakes that can be used to delegate these calls functional equivalents is worth while. Another useful extension can be to track allocation and freeing of memory, then in a test fixture setup tracking can be enabled, and in the teardown it can be checked.

CMUtils

This component provides string manipulation and other utility functions, in most cases it is preferable to have a working double than the standard fff fake. If you have a source code distribution of the runtime code I would attempt to link this with the tests.

SysTime and SysTimeRTC

One of the great advantages of Unit Testing in embedded systems is being able to run tests faster than realtime. Develop custom_fakes that allow you to take control of the progress of time.

Continuous Integration

Tests are only useful when they are run. Setting up a continuous integration system to build and test each component every time there is a change to the source code is the way to go.

Continuous Delivery

How far can you go towards continuous delivery? Using a combination of free tools, and the CODESYS Test Manager I have set up delivery pipelines that build the embedded code, run unit tests, performed static analysis, generated documentation, package up instrument firmware packages, build and test CODESYS libraries, automated version number management, create CODESYS packages, deploy the code into test systems and invoke automated testing (integration and system). If the tests all pass then the packages can be promoted to potential release candidates ready for final human validation as required.

 

Cross development using eclipse and GCC for the RPi

Introduction

When I decided to use eclipse to do some cross development for the Raspberry Pi hosted on windows I was surprised to find that I found lots of useful posts elsewhere that gave a part of the solution, or worked well on a Linux host. I found both of the sites below to be particularly helpful. http://www.gurucoding.com/en/raspberry_pi_eclipse/index.php
http://gnutoolchains.com/raspberry/tutorial/
My blog post Using google test with CDT in eclipse gives details on how to install eclipse CDT, which is an assumed starting point for this post.

Install GCC Cross compiler

It is possible to build your own GCC cross compiler, however this is a complex process and prebuilt versions are available. I choose to download from http://gnutoolchains.com/raspberry/, and selected raspberry-gcc4.6.3.exe to match wheezy raspbian. Installation was as simple as running the executable and accepting the terms of the license.

Synchronise header file and library versions

This step is required to ensure that the versions of headers and libraries used on the Raspberry Pi match those used by the cross compiler.
Run c:SysGCCRaspberryTOOLSUpdateSysroot.exe
Press Select… and setup a new SSH connection to your Raspberry PI (Mine is running a newly installed image and has the default username and password).
Click Connect and then save the key when prompted, then click Synchronize, wait while the headers and libraries are copied (This takes a few minutes).
NOTE: Whenever you update your RPi it is a good idea to resynchronize to ensure that your development environment remains in step with your target.

Configure eclipse for cross compilation

Open eclipse and in the Project Explorer right click and select New…->C++ Project. Select the Hello World C++ Project and Cross GCC, give the project a name.
Click Next> and customise as you wish
Click Next>
Click Next> and specify the cross-compiler prefix as arm-linux-gnueabihf- and cross-compiler path as C:SysGCCRaspberrybin.
Click Finish and then build the project, there should be no errors.

Configure RPi for gdb

Run SmarTY.exe from C:SysGCCRaspberryTOOLSPortableSmartty, and open the connection to your RPi.
Enter these commands
mkdir remote-debugging
Verify that gdbserver is on the path and the version of gdbserver that is installed
gdbserver --version

To automate the use of gdb on the target RPi it needs to have the DataStore server running. 
 
Download the server from http://download.eclipse.org/tm/downloads/index.php, I used the 3.6M4 release and downloaded rseserver-linux-3.6-M4.tar to the /tmp directory on the RPi. Following the install advice from the eclipse help I executed these commands on the RPi

sudo mkdir /opt/rseservercd /opt/rseserversudo tar xf /tmp/rseserver-linux-3.6-M4.tar

The daemon needs to be run as root, so it can be manually started by

sudo su
cd /opt/rseserver
perl ./daemon.pl &

To have it start automatically each time the RPi reboots, edit /etc/rc.local and just before the exit 0 at the end of the default file launch the server

cd /opt/rseserver
perl ./daemon.pl &

When the RPi reboots you should see a message that says

Daemon running on: raspberry, port: 4075 

Configure eclipse for Cross debugging

Right click on the HelloWorld project in the project explorer and New->File, set the name to .gdbinit and click Finish.
In the file set sys root to point to the cross tools set sysroot C:SysGCCRaspberryarm-linux-gnueabihfsysroot
 

In the project explorer right click on the HelloWorld project and select Debug As->Debug Configurations…, then select C/C++ Remote Application and click the New button (circled).

In the Debug Configurations Dialog the first step is to configure a connection to the Raspberry Pi, to do this, next to Connection: click New…
 
Select a Remote System type of Linux, and click Next>
Enter the IP address of your RPi in Host name:, name the connection and set a description, then Next>.
Click Next>

 

Click Finish, ensure that the Connection: is set to your new connection
Then click Browse… under Remote Absolute File Path for C/C++ Application:

 

Then try to expand My Home, you will be prompted for user credentials and certificates

 

 

 

Select the remote-debugging directory and click OK.

 

When the binary is transferred to the raspberry pi we need to ensure that it has execute permissions set, so in the Commands to execute before application enter chmod 777 /home/pi/remote-debugging/HelloWorld
Now in the Debug Configurations dialog select the Debugger tab and on the Main sub-tab browse to the arm-linux-gnueabihf-gdb.exe debugger.
Now select the Gdbserver Settings sub-tab, the default settings worked for me and looked like this.
Apply these settings, and Close.
Click Window->Perspective->Open Perspective->Other... select Remote System Explorer, and click OK.
In the Remote Systems tab right click on your connection and select Connect. (I found if I didn’t connect to the RPi before launching the debugger the launch would fail, retrying usually worked – but this is cleaner).
Now select Run->Debug Configurations, ensure your configuration is selected (it should be) and click Debug. You will be prompted to confirm the perspective switch, tick to Remember your decision and click Yes.

You should then see your application stopped on the first line and ready to be debugged

I have tested this setup with setting breakpoints, viewing disassembly, stepping into and out of functions and inspecting variables. It all seems to work, however I have not yet diagnosed the error Cannot access memory at address 0x0. I will update this post if/when I get to the bottom of it.

Clean error

If you don’t have rm.exe on your path you will see an error like this when you clean the project.
This can be resolved by downloading rm.exe as part of MinGW, find the path to rm.exe, (with a default install it is C:MinGWmsys1.0bin). Add this to the end of your windows PATH and restart eclipse.

Further Reading

If you find this tutorial helpful you may find my previous postings on eclipse helpful too
Unit testing with googletest
Code coverage with Gcov
Static analysis with CppCheck
I develop for RPi by having a unit test project that compiles and runs on my PC for speed, and then a cross compiled project that shares the same source code and runs on the RPi.
 
 




Static analysis with Cppcheck in eclipse CDT and Jenkins

Static analysis tools look for a wide range of potential errors with code that compilers do not look for.    Cppcheck is a an open source static analysis tool, it is extensible and being actively developed. These are the sorts of errors that can be found

  • Out of bounds checking
  • Memory leaks checking
  • Detect possible null pointer dereferences
  • Check for uninitialized variables
  • Check for invalid usage of STL
  • Checking exception safety
  • Warn if obsolete or unsafe functions are used
  • Warn about unused or redundant code
  • Detect various suspicious code indicating bugs

This post walks through the process of installing Cppcheck and integrating it with eclipse CDT as well as on Jenkins.

Installing Cppcheck

Download and run the msi installer from http://cppcheck.sourceforge.net. I clicked on through accepting the defaults.
NOTE: I installed version 1.71, originally I tried the x64 version but had problems, the x86 version worked fine.
To understand how to run cppcheck refer to the manual.

Installing the eclipse plugin

In eclipse click Help->Eclipse Marketplace and search for Cppcheclipse.
Click Install then Confirm >
Accept the terms of the license and Finish. (I was prompted about installing unsigned software – I chose to continue). When prompted restart eclipse.
The next step is to configure the plugin. In Eclipse go to Window->Preferences->C/C++->cppcheclipse and set the path for the binary
Now review the Problems and Settings preferences, see below for the settings I use, I have all Problems enabled.
Now In the C/C++ perspective select the project that you want to check, right click and select cppcheck->Run cppcheck.
Any problems found are shown in the Problems tab
Double clicking on an issue takes you to the offending code (could this be a deliberate error?)

 

 

NOTE: I had repeated problems with errors: URI is not absolute
I worked around this by changing all include paths for the project to absolute paths. Not a real solution for me, for now I change the paths to analyse and then change back afterwards, or ignore the eclipse plugin and run on the command line.

Installing the Jenkins Plugin

Log in to Jenkins and go to Jenkins->Manage Jenkins->Mange Plugins, select the Available Plugins tab and Filter for cppcheck.
check the Install check box and select Install without restarting.
At this point you need to configure Jenkins to run the analysis and report on it, static analysis typically takes much longer than compilation for the same code. So in a real world application I would create a new Jenkins Job that checks out the code and runs the analysis. For my home project I’ll just extend the existing job.
Edit the node configuration for the build slave (Jenkins->Manage Jenkins->Manage Nodes) to add a label for cppcheck and also set an environment variable to say where cppcheck is installed.
Now in your Jenkins Job configuration – make it depend on the cppcheck label
Add a build step to run cppcheck, the example below is what I have, note the 2> which redirects stderr into a file, this is needed to capture the xml output.
Add a Post Build step to publish the cppcheck results (Once it is working play with the advanced options).
Now run a couple of builds and you should see graphing of the analysis results, be able to drill into the results down to the specific lines in files.

gcov code coverage in eclipse and Jenkins

Introduction

This post gives step by step instructions for adding code coverage with gcov to a google test eclipse project that is built as part of a CI process on Jenkins. This post starts from the point of already having a project compiled by a gnu compiler, in an eclipse CDT project that is being build on Jenkins. These posts give the information required to get to this stage.

Using google test with CDT in eclipse
Integrating SVN, Trac and Jenkins with eclipse
Automating eclipse CDT build on Jenkins

To enable code coverage with gcov the project needs to be instrumented (build with flags that cause the raw coverage information to be saved when an executable runs). Having built the code with these flags enabled, and run the executable, both eclipse and Jenkins can be configured to view the coverage.

Enabling code coverage in the build

To determine what code coverage the unit tests have in the unit test project in eclipse: Right click on the project and select Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Compiler->Debugging and check Generate gov information (-ftest-coverage -profile-arcs).

Still in the Properties->C/C++ Build->Settings->Tool Settings select MinGW C++ Linker->Miscellaneous and then in the Linker flags box add -ftest-coverage -fprofile-arcs.
Click OK to close the properties dialog. clean the project and the build, then look in the Debug folder and there should be a .gcno file for every source file.

Coverage Reports in eclipse

CDT includes support for gov, however this support relies on external tools that must be in the path. I tried to add them to the path in the eclipse project, I couldn’t get it to work, so I had to extend the Windows environment variable path. The path needs to include a path to addr2line, c++filt and nm, with my install of minGW I added c:mingwbin. Shutdown and restart eclipse so that it has access to the new path.
Now run your unit test application in eclipse, this will generate a .gcda for each source file. Now if you open any .gcda or .gcno file you should see
Click OK and the gov tab should be opened with coverage shown
NOTE: If you get an error here the most likely reason is that the gcov data is not all from a single binary version of the test application. The quick way to resolve this is to delete the Debug directory, rebuild and rerun the tests.
NOTE: When you double click on a file in the gov tab it opens the associated source file and should show line by line the coverage. Except in my scenario it doesn’t for linked folders. To see line by line coverage open the file of interest from the linked folders, open the file from under the unit test project, the coverage will show. This is being tracked as bug 447554 in the eclipse bugzilla. (Update 9 January 2016 – This is now fixed in updates-nightly-mars, Thank you Jeff)

Coverage in Jenkins

To get a coverage report added to the Jenkins job we have to convert the gcov output into a a format that can be understood by Jenkins (using gcovr) and then configure Jenkins with the cobertura plugin.

gcovr

gcovr is a python application, so before it can be used you need python installed on the jenkins slave. Download and install active python from https://www.activestate.com/activepython/downloads. In my case I downloaded the ActivePython 2.7.10.12 (x64). I accepted all defaults on the installer.
Open a command prompt and install gcovr
pypm -g install gcovr

I found it very hard to get the correct options on gcovr for the files I wanted in the output. I installed activepython and gcovr in the same way on my desktop machine, and experimented in the eclipse workspace. For me with an eclipse workspace at C:UsersDavidworkspace. Running the command below from C:UsersDavidworkspacehex2numSource I got the desired output. i.e. coverage for each source and include file being tested in hex2num.

python c:Python27Scriptsgcovr -r . –object-directory= ….hex2numUnitTestDebug -f .*\hex2num\Include\ -f .*\hex2num\Source\ 

cobertura

Cobertura is a plugin for Jenkins that displays code coverage. To install the plugin login to Jenkins and go to Manage Jenkins->Mange Plugins->Available, select Cobertura Plugin, click Install without Restart.

For the Jenkins job you are configuring (in this example hex2num) go to the job configuration page, select Add Build Step->Execute Windows batch command. Add the following to go to the correct directory, I have added flags to generate xml output to a named file.

cd hex2numsource

python c:Python27Scriptsgcovr -r . –object-directory= ….hex2numUnitTestDebug -f .*\hex2num\Include\ -f .*\hex2num\Source\ -x -o ….gcovr.xml

Then select Add post-build action->Publish Cobertura Coverage Report, enter the path to the generated results file. Selecting Advanced allows a variety of options to be set.
Run a build and you should start to see code coverage reports, once a second build has been run you should start to see graphs. You can also drill in for more details.

Getting painted files to show in Cobertura

Although cobertura is displaying coverage there are two problems
  1. The package names don’t read well
  2. Painted source files don’t show as cobertura cannot find the source files

To resolve this I wrote a small python script to patch the paths in the gcovr.xml files. Save this source as C:Python27ScriptsCorrectGcovrPaths.py.

try:
import xml.etree.cElementTree as ET
except ImportError:
import xml.etree.ElementTree as ET
import sys
gcovrXmlFilename=sys.argv[1]
paths = sys.argv[2:]

tree = ET.ElementTree(file=gcovrXmlFilename)
for packageElement,path in zip(tree.iter(tag=’package’),paths):
packageElement.set(‘name’,path)
for classElement in packageElement.iterfind(‘classes/class’):
filename = classElement.get(‘filename’)
filename = filename.split(‘\’)[-1:][0]
filename = path+”/”+filename
classElement.set(‘filename’, filename)
tree.write(gcovrXmlFilename)

In the jenkins job, change the windows batch command that runs gcovr so that it looks like this.

The script reads the file in the first argument (gcovr.xml), renames the first package(directory) to the next argument and sets the path for all classes (files) in the package, the second argument is processed similarly. More arguments can be added for additional packages.
In Jenkins you can then see nicely painted sources like this

Automating eclipse CDT build on Jenkins

In my previous posts I have shown how to setup Jenkins to work with SVN and trac running on the Raspberry PI. I have also shown how to configure eclipse to work with google test and how to configure eclipse to work with SVN and trac. This post covers how to automate the build of the eclipse projects under Jenkins and how automate running the unit tests.

Jenkins Configuration

Jenkins Slave Setup

First of all install all of the tools that you need for your build on a Jenkins slave, in my case eclipse CDT with a selection of plugins, and Mingw. Eclipse is not on the path by default, so I created a system environment variable ECLIPSE_DIR on the slave, with the path to where eclipse is installed. I also restarted the Jenkins slave service so that it had access to the new environment variable.
Decide on a label for these tools, I will use two, eclipse mingw. Login to Jenkins to add the labels to the slave with the tools installed. Go to Manage Jenkins->Manage Nodes, select the node and add the labels

 

Jenkins Job Configuration

Add the job to Jenkins, from the Jenkins home page select New Item, name the job and select Freestyle project, click OK. My example project is called Hex2Num, a simple utility I’ve written, it consists of two eclipse projects (a unit test project and the application), the unit tests are written using googletest, documentation is handled with doxygen, gcov is used for code coverage.
There is quite a bit of configuration, on the job page, so section by section

Name and Description

Fill in a meaningful description

Trac

If you are using trac and have integrated trac and Jenkins (see Integrating Trac and Jenkins) then fill in the URL to access trac.

Restricting where the build runs

Only the build to run on slaves that have the labels mingW and eclipse
Source Code Management

The source is stored in a single module in subversion, fill in the URL and any required credentials.

Build

Click Add build step->Execute windows batch command, this command builds all of the projects in the workspace as DEBUG.

Warnings

Click Add Post-Build action->Scan for compiler warnings and select gnu 4

 

Google Tests

Go back and add another  build step, Click Add build step->Execute windows batch command, this command executes the unit test application and generates an xml results file that can be interpreted as Unit results.
Add another post-build action, Click Add Post-Build action->Publish Unit test result report and enter the name of the result file.

Results

After a few builds have been run two graphs will appear on the Jenkins page for the job.

Integrating SVN, trac and jenkins with eclipse CDT

I have previously posted on how to install trac, SVN and jenkins on the Raspberry Pi, and also on how to install (see the bottom of this post for related posts). When using Eclipse there are helpful plugins that tightly integrate all of these tools. This post covers the installation and configuration of these tools.
NOTE: I am installing in the Mars release of Eclipse CDT.

Subversion – Install Subclipse

There are two competing SVN integrations for Eclipse, subclipse and subversive. Both appear to be good, subclipse is supported by tigris (the organisation behind subversion), subversive is supported as an official Eclipse project. I have personally used subclipse for a long time and see no compelling reason to change.
If you use any other SVN client to work on the same checkout as Eclipse then they must use the same working copy format. See the subclipse download and install page for details. Because I also use tortoise SVN and am currently using version 1.8.x,  I need to use subclipse 1.10.x. The update site for this version is http://subclipse.tigris.org/update_1.10.x
In Eclipse go to Help->Install New Software…, in the Install dialog press the Add… button paste in the url for the update site that you require and enter a name.
Click OK and then select Subclipse and SVNKit as shown
click through accepting the license agreement and wait for the install to complete. I got a warning about unsigned content during the install and chose to accept the installation.
The built in help for subclipse is good, in Eclipse click Help->Help Contents and then find the topic Subclipse – Subversion Eclipse Plugin, the getting started section walks you through how to add a new project or how to access an existing one.

Trac and Jenkins install Mylyn Connectors

In Eclipse go to Help->Install New Software…, in the Install dialog in the Work with: drop down pick –All Available Sites– and then under Collaboration check Mylyn Builds Connector: Hudson/Jenkins and Mylyn Tasks Connector : Trac.
click through accepting the license agreement and wait for the install to complete.

Configuring the trac connector

Switch to the SVN Repository Exploring perspective in Eclipse, in the bottom left of the display you should see the Task Repositories view. In this view right click and Add Task Repository, or click on the  icon, select the Trac repository type and click Next.
NOTE: you may be prompted to setup a Secure Storage Password.
In the Add Task Repository… dialog, for the Server enter the URL that you use to browse to the trac repository, in the Label field put a short description, complete the User ID and Password that you use to log in to trac. Validate Settings and then Finish.
When you click Next you will be prompted to Add a new query, queries give you the ability to filter lists of trac tickets to those appropriate to you, a component, a release or whatever. The example below shows all of my open tickets.
To then see the results of the queries click Window->Show View->Other, then under Mylyn select Task List and click OK.
In the Task List it is possible to expand the queries to see lists of tickets, and the tickets can be opened and worked on. See below for an example.

Configuring the Jenkins Connector

Open the Mylyn Builds View (Click Window->Show View->Other…, and find Builds under Mylyn)
In the Builds view either click on Create a build server or on the icon. Select Hudson (supports Jenkins).
Fill in the Server:, Label:, User: and Password:, fields assuming you are using password authentication. For me the server URL is http://xxx.xxx.xxx.xxx:8080 where xxx.xxx.xxx.xxx is the IP address of my server. Check any build plans you are interested in , validate your settings and click finish.
From this builds view all build plans selected are visible, builds can be manually started, the build history is available and details for individual builds can be accessed (Such as warnings, test results and changes made).

Related Posts

Using Google Test with CDT in eclipse (Covers the installation of Eclipse CDT and MinGW)

Using Google Test with CDT in eclipse

Introduction

I like to use test driven development, currently my preferred framework is googletest. When I came to use eclipse CDT with the MinGW toolchain I found I had lots of little issues to get over to achieve what I wanted, namely a rapid TDD environment that I could also build from the command line (so that it can be automated under Jenkins). This post collects together the steps to get a simple application and associated unit test application building.

Installation

MinGW

Clicked the Download Installer button on the MinGw home page http://mingw.org/. This downloads an installer for MinGW. I then selected the following components
 screen-shot-2016-10-13-at-18-23-29

Java

eclipse CDT

I downloaded the Eclipse Installer from http://www.eclipse.org/downloads and ran the install selecting the C/C++ development environment.

Create Projects

My personal preference is to have two projects for a component, the actual component (executable, library etc), and an executable that is a unit test for the code in that component. I find this works well for me as a pattern because it works the same if I am working on a library or cross compiling.
Launch eclipse, close the welcome menu and you should end up in the C/C++ perspective. In the Project Explorer right click and select new C/C++ Project. Select Executable->Empty Project and the MinGW GCC toolchain, give your project a name, for this example I have chosen the name demo.
Click Finish. Then right click on the project and add a new folder called Main, in that folder create a new file called demo.cpp. In Main.cpp create a minimal main function as shown and save the file. (If you forget to save you may well see an error about undefined reference to WinMain@16)
int main(int argc, char **argv)
{
return -1;
}
When I got to this point I found that I could build the program, and debug it without error. But if I tried to run it windows pops up an error saying that demo.exe has stopped working. This can be resolved by changing the linker flags. On the demo project, select properties then C/C++ Build->Settings. Set the Configuration to [All Configurations], then under Tool Settings select MinGW C++ Linker->Miscellaneous and in the Linker flags box type -static-libgcc -static-libstdc++ as shown.
You should now be able to build, run and debug demo.exe.
Repeat the above process to create a second project called demotest, ensure that you can build, run and debug remotest too.

Add Googletest to the test project

I downloaded googletest-release-1.7.0 from https://github.com/google/googletest/releases and unzipped the content locally. Google now recommend compiling google test with each project, the easiest way of achieving this I find is merging google test into a single header and source file. To do this you need python installed, I downloaded and installed python 2.7.10 from http://www.python.org/downloads/
Then open a command prompt in the root of the unzipped googletest-release-1.7.0 directory and run
.scriptsfuse_gtest_files.py . <demotest project dir>contrib
where <demotest project dir> is the path to the demotest project in your workspace. Now open eclipse and you should see gtest in the demotest project.
Next we need to ensure that the include path finds the test headers to do this, open the properties dialog for the remotest project. Under C/C++ General->Paths and Symbols, select [All Configurations] and GNU C++, then add the contrib include directory as a workspace include.
Prove the project still builds – For me it builds with a single compiler warning – I will ignore that for now.
The next step is to add code to run google test. Edit demotestMainMain.cpp so that it has the content below
#include “gtest/gtest.h”
int main(int argc, char **argv) {
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}
At this point if you build and run you should get this output.
[==========] Running 0 tests from 0 test cases.
[==========] 0 tests from 0 test cases ran. (0 ms total)
[  PASSED  ] 0 tests.

Starting TDD

The first test I want is to prove that my demo.exe returns 0 when called with no arguments.
First addd a folder called Tests to the remotest project, in that create a
Create two folders in the demo project called Source and Include. In the demotest project add a folder called Tests, and in that a new file DemoTest.cpp with this content
#include“gtest/gtest.h”
#include“demo.h”
namespace
{
class DemoMainTest : public :: testing::Test
{
};
TEST_F(DemoMainTest,Returns0)
{
ASSERT_EQ(0, ::Demo(0, NULL));
}
}
A TDD purist would say I am doing too much at once, this adds a test to show that a function called Demo, called with two NULL arguments returns 0. If you try to compile now the build will fail because the file demo.h doesn’t exist.
To get this to compile and link we need to add the file Demo.h and Demo.cpp, but these files should actually be part of the demo project and not demotest.
In the demo project add a new folder Include and in that add Demo.h with this content
int Demo(int argc, char **argv);
Still in the demo project ass a new folder Source and in that add Demo.cpp with this content
int Demo(int argc, char **argv)
{
return -1;
}
In the demo project properties, under C/C++ General->Paths and Symbols, select [All Configurations] and GNU C++, then add the Include directory as a workspace Include.
Also edit the existing Main.cpp in the demo project to call the demo function.
#include “demo.h”
int main(int argc, char **argv)
{
return Demo(argc,argv);
}

At this stage the demo project should compile and link.

We now need to get the demotest project to reference this source and include path.
In the demotest project properties under C/C++ General->Paths and Symbols, in the Source Location tab click the Link Folder… button, click Advanced>> , check Link to folder in the file system, click Variables…, select WORKSPACE_LOC and click Extend…, find demo/source, click OK all the way out.
In the demotest project properties under C/C++ General->Paths and Symbols, select [All Configurations] and GNU C++, then add the Include directory as a workspace include.
All being well, the workspace should now look like this
You can now build, and run, the test should fail
[==========] Running 1 test from 1 test case.
[———-] Global test environment set-up.
[———-] 1 test from DemoMainTest
[ RUN      ] DemoMainTest.Returns0
..TestsDemoTest.cpp:12: Failure
Value of: ::Demo(0, __null)
  Actual: -1
Expected: 0
[  FAILED  ] DemoMainTest.Returns0 (0 ms)
[———-] 1 test from DemoMainTest (0 ms total)
[———-] Global test environment tear-down
[==========] 1 test from 1 test case ran. (0 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] DemoMainTest.Returns0
 1 FAILED TEST
Change the return value in Demo.cpp to 0, save, rebuild and re-run and the test should pass.
[==========] Running 1 test from 1 test case.
[———-] Global test environment set-up.
[———-] 1 test from DemoMainTest
[ RUN      ] DemoMainTest.Returns0
[       OK ] DemoMainTest.Returns0 (0 ms)
[———-] 1 test from DemoMainTest (0 ms total)
[———-] Global test environment tear-down
[==========] 1 test from 1 test case ran. (0 ms total)
[  PASSED  ] 1 test.
Now we are in a good position to start TDDing, as long as you add test files to the Tests folder, source to the Source folder and include files to the includes folder there should be no further need to mess with the build.

Test Runner

At this stage we are up and running, but it is still a bit clunky running the tests. Fortunately eclipse CDT has a test runner that supports google test. Unfortunately it is not installed by default. To install go to Help->Install New Software…, choose to Work with: –All Available Sites– and then under Programming Languages select C/C++ Unit Testing Support, click Next>, Next>, Finish and wait for the install to complete.
Restart eclipse when prompted.
Select Window->Show View->Other… and select C/C++ Unit
In the Project Explorer right click on demotest and then Run As->Run Configurations…, double click C/C++ Unit and then under the C/C++ Testing tab select Google Tests Runner.
Click Run and all being well you should see
Now you can really start moving with TDD 🙂

Version Control

At this stage it is a good idea to put the project under version control. Under eclipse the workspace is specific to a single folder on a specific machine, so it should not normally be placed under version control. Also any files generated by the build do not need to be version controlled, so before looking at what files to version control clean both projects from inside eclipse. If you are not using eclipse to manage your version control it is then a good idea to exit eclipse.
Using explorer the workspace looks like this
Both the RemoteSystemsTempFiles and .metadata folders are created by eclipse and do not need to be version controlled. The Debug folder under each project is created when a Debug build is performed and also does not need to be version controlled, if a Release build has been performed then there will be a folder called Release, again this doesn’t need to be version controlled. Everything else should be placed under version control.
To prove you have everything required under version control, it is a good idea at this point to verify that a clean checkout of your code builds. To do this create a new empty workspace directory (e.g. Workspace2) and checkout the projects from your version control system into that workspace. Then launch eclipse and select Workspace2 as your workspace
When eclipse starts there will be no projects in the Project Explorer, even though the projects exist in the Workspace2 folder on the file system. Right click in the Project Explorer and select Import…, then General->Existing Projects into Workspace
click Next>, then Browse…, this will open a Browse For Folder dialog opened on the workspace, click OK.
Then click Finish on the Import dialog, both projects should then be imported and can be build as before.
NOTE: Depending on your version control system and any plugins that may be installed you may be able to import projects directly from the VCS into a new workspace.

Command Line Build

The managed build in eclipse CDT is very easy to manage when working in the GUI, however there are situations when a command line build is required, such as when projects need to be built by a continuous integration system. Typically under CI the command line will need to cope with the situation where projects have been checked out from the VCS into a clean workspace folder, this example when executed from the root of the workspace folder creates the eclipse workspace artefacts, imports all of the projects in the workspace and builds the Debug configuration for each project.

<path to eclipse>eclipsec.exe –launcher.suppressErrors -nosplash -application org.eclipse.cdt.managedbuilder.core.headlessbuild -data . -importAll . -no-indexer -build “.*/Debug”

The first few arguments on this command line are standard eclipse arguments, see running eclipse and eclipse runtime arguments for details.
There are many other options – at the time of writing the options are
Usage:
   -import     {[uri:/]/path/to/project}
   -importAll  {[uri:/]/path/to/projectTreeURI} Import all projects under URI
   -build      {project_name_reg_ex{/config_reg_ex} | all}
   -cleanBuild {project_name_reg_ex{/config_reg_ex} | all}
   -no-indexer Disable indexer
   -I          {include_path} additional include_path to add to tools
   -include    {include_file} additional include_file to pass to tools
   -D          {prepoc_define} addition preprocessor defines to pass to the tools
   -E          {var=value} replace/add value to environment variable when running all tools
   -Ea         {var=value} append value to environment variable when running all tools
   -Ep         {var=value} prepend value to environment variable when running all tools
   -Er         {var} remove/unset the given environment variable
   -T          {toolid} {optionid=value} replace a tool option value in each configuration built
   -Ta         {toolid} {optionid=value} append to a tool option value in each configuration built
   -Tp         {toolid} {optionid=value} prepend to a tool option value in each configuration built
   -Tr         {toolid} {optionid=value} remove a tool option value in each configuration built
               Tool option values are parsed as a string, comma separated list of strings or a boolean based on the option’s type