My C++, Java unit test development experience

1. Unit Test Exp
Hieu T. Le

2. What is Unit Test?
What is a GOOD unit test?
• Automatic
• Thorough
• Repeatable
• Independent
• Professional

3. Unit Test Framework
• Provide a framework to
– Initialize/shutdown unit test environment
– Automated check fail/pass
• http://en.wikipedia.org/wiki/List_of_unit_test
ing_frameworks
– JUnit, CppUnit, CUnit, PhpUnit, NUnit, …

4. Unit Test Difficulties
• Test Case Generate
• Test Data Generate
• Environment
• Framework
• Effort vs. Schedule
• Thinking
• Process

5. Unit Test Environment
• Language: C, C++, Java
• Platform: Linux
• Framework: CppUnit, CUnit, JUnit, Google Test
• Tools: GCov, LCov, Jenkins

6. PROJECT A – PHASE 1
Language: C
Platform: vxWorks (Linux simulator)

7. Project A – Phase 1
• Difficulties
– Newbie team member
– Input return boolean, many alternatives path
– No hardware, use stub for many
vxWorks/hardware relating
– Schedule rush

8. Project A – Phase 1
• How can we work out?
– Experienced engineer build up unit test
framework for project
– Engineer does
• Basic test case: good case, bad case
• Additional test case for each code path
• Test data
• Verify result

9. Project A – Phase 1
• Lesson learnt
– It is bad when we focus too much into alternative
cases
– It is bad when we focus too much into unit test
coverage
– Unit test cannot be verified manually by eyes

10. PROJECT A – PHASE 2
Language: C
Platform: vxWorks (Linux simulator)

11. Project A – Phase 2
• Difficulties (from Phase 1)
– Unit test is verified manually
– Too many alternative cases
– Test data generating

12. Project A – Phase 2
• How can we work out?
– Experienced engineer refactor unit test framework
of phase 1
• Setup mechanism to ASSERT and automation
• Setup mechanism to automated generate test data
– Engineer does
• Run tool to generate test data for good/bad case
• Write additional test case for some alternatives code
path

13. Project A – Phase 2
• Lesson learnt
– Use tool to generate test data automatically
– Some engineer setup data without resetting it, it
makes other test case fail
– Should setup framework for mock object
– Should enforce fixing fail test case ASAP

14. PROJECT B
Language: Java, JNI, C++
Platform: Embedded Linux (cross run on PC)

15. Project B
• Difficulties
– Full stack application run on embedded board
which contains reference to many components
– Boot up time is long
– Cannot initialize all components for testing since it
depending on hardware
– Cannot run component standalone
– Cannot run on desktop PC

16. Project B

17. Project B
• How can we solve it?
– Experienced engineer setup a framework of unit
test using mock object approach
• Write mock object to wrap some components which
has many dependencies and depending on hardware
– Engineer does
• Write test case for the test component using developed
mock object

18. Project B
Mock Object

19. Project B
• Lesson learnt
– Use mock object so that we can control the result
– Use mock object to wrap some hardware
depending component
• Technologies used:
– Junit
– JMockit, Mockito

20. Thank You