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Generate Code Coverage for NDK Projects

Generate Code Coverage for NDK Projects

To generate code coverage for the NDK-build based project in Windows and Linux, you need to prefix rktracer to ndk-build command and rebuild the application.

Example NDK-build

Step 1:Enable the RKTracer tool and rebuild the application.

ndk-build NDK_PROJECT_PATH=.  APP_BUILD_SCRIPT=.\app\Android.mk v=1

TO

rktracer ndk-build NDK_PROJECT_PATH=.  APP_BUILD_SCRIPT=.\app\Android.mk v=1

RKTracer instruments the preprocessed file with “c:\rktracer/lib/librklic-x86_64-w64-mingw32.exe ” and writes out the instrumented preprocessed file to “prime.i” file. Also, it stores the metadata, structure of instrumentation, and copy of source file content to JSON file. RKTracer tool automatically adds runtime at linking time. The tool will refer to rktracer.config for internal configuration at the time of instrumentation.

 

Step 2: Testing instrumented application.

If you generate a shared library push it to the target device or add it to application.apk.

Install the APK in the device(don’t disconnect the device from the host machine) execute the command by opening the command prompt or terminal from the project directory, i.e., parallel to the rktracer folder(rktracer folder will get generate once we instrument the project with rktracer tool). So that coverage data from logcat will get collected from the device. Then start testing the app on the device.

adb -e logcat > rk-coverage.txt 2>&1

This command will write code coverage data from logcat to the rk-coverage.txt file. You should not change the file name, i.e., rk-coverage.txt. RKTracer tool will consider the rk-coverage.txt file as a coverage data file.RKTracer tool by default writes coverage data to the target device and logcat. The RKTracer tool will try to write at multiple places, and you check this in logcat output. Here is the sample logcat output when I search for the keyword “rk-coverage.”

You can also pull the coverage data from the phone device, you can execute the command. 

adb pull  /data/data/com.example.app-name/rk-coverage.txt 

You need to pull and copy the rk-coverage.txt file to the application working folder where you have the rktracer folder in the application directory.

Coverage data file not found after testing.

RKTracer tool uses the following approaches to save coverage data.

  • Run unit/functional testing, and at the end RKTracer tool will automatically save coverage data on the host/embedded target/server machine, that is, write coverage data to the rk-coverage.txt file.
  • Send a signal to the application running in an infinite loop to trigger and save coverage data. 
  • The application under test has crashed in the middle of testing on the host or target device. RKTracer saves coverage data to rk-coverage.txt and generate reports to check the point of a crash in reports.
  • Embedded devices without a file system or not connected to host while testing. In this case, rktracer RAW mode comes in to picture. You need to save the coverage data from the RKTracer variable. 

Suppose you cannot find the rk-coverage.txt file in the project working folder or target server machine. An application under test has not exited with the proper exit handler, i.e., atexit() handler, or your application might be running in an infinite loop. You can use the following two methods to save coverage data from memory to the file system.

Save coverage data when a particular function is executed at runtime testing.

Identify a function/method name in your application (ensure this function/method is not excluded from RKTracer instrumentation or file with this function). Then copy the function name and edit the rktracer.config in the RKTracer installation folder. 

For C programming language:  Add a new line at the end of rktracer.config file with “c-function-writeout” and function name. Here the function name is case sensitive, and you should also add empty braces, i.e., () at the end of a function name. In case if you have a function with an input parameter, it should still be empty braces. You can add multiple function names with one space to the list, as shown below.

  • c-function-writeout main()
  • c-function-writeout main()  OnCreate() fun()

For C++ programming language: Add a new line at the end of rktracer.config file with “c++-function-writeout” and function name. Here the function name is case sensitive, and you should also add empty braces, i.e., () at the end of a function name. In case if you have a function with an input parameter, it should still be empty braces. You can add multiple function names with one space to the list, as shown below.

  • c++-function-writeout main()
  • c++-function-writeout main()  OnCreate() fun()

After adding function name to rktracer.config file. You need to rebuild the application to re-instrument using rktracer. Coverage data will be saved to the rk-coverage.txt file when this function executes at runtime testing. 

Send a signal to save coverage data.

We can send a signal to the application running in an infinite loop to save coverage data to rk-coverage.txt.

  • Windows: send a kill signal using keys in the keyboard, i.e., Control+Pause/break. Contact support if you would like to add additional signal command to save coverage data at runtime testing.
  • Linux/Unix: Send a SIGWINCH signal: killall -SIGWINCH a.out or kill -SIGWINCH Process ID number. 

Step 3:Generate Code Coverage HTML reports

Once you have the rk-coverage.txt file, you need to run the command “rkresults” to generate HTML reports. Ensure that you run the “rkresults” command in the application root folder or where you have the “rktracer” folder generated at the time of build/Instrumentation.

rkresults command will search coverage data file “rk-coverage.txt” and map with JSON files (generated during instrumentation) in the rktracer folder and generate the HTML reports. You can manually open the HTML report using index.html.

Generate code coverage for selected functions/files/folder

Generate coverage reports  for the selected folders

C:\project\sound\drivers\base\power\

C:\project\sound\drivers\base\power\firmware_loader\

C:\project\sound\drivers\core\

C:\project\sound\security\keys\

C:\project\sound\security\lockdown\

Suppose you need code coverage for source files from three different folders, i.e., core, keys, power, and ignore coverage for folders firmware_loader and lockdown. Edit rktracer.config in the RKTracer installation folder and go to the end of the file add the following information. 

ignore *.c

instrument */power/* */core/* */keys/*

never */firmware_loader/* */lockdown/*

ignore *.c = Ignores all C source files from instrumentation

Instrument = Instrument source files from given folders

never = ignore selected folder  

Generate coverage reports only for selected functions from three different files.

fun_X() in source-file-X 

fun_Y() in source-file-Y

fun_Z() in source-file-Z

Suppose you need code coverage for selected functions from three different files. Edit rktracer.config in the RKTracer installation folder and go to the end of the file and set the following variables as shown below.  

ignore *.c

instrument *source-file-X.c *source-file-Y.c *source-file-Z.c

function-ignore *

function-instrument fun_X() fun_Y() fun_Z()

ignore *.c = Ignore all C programming source files

instrument *file-X.c *file-Y.c *file-Z.c   = Instrument only these three source files.

function-ignore * = Then ignore all functions in the above three files.

function-instrument fun_X() fun_Y() fun_Z() = Don’t ignore these three functions from these three files from instrumentation.

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