C++ is a powerful language when used by a seasoned developer. It is being used everywhere from operating systems and compilers to cross platform mobile apps development. But this power comes with a cost - C++ programming is not simple nor easy – with memory leaks, stack overflows and strange exceptions, a software developer needs all of the power he can use. By harnessing the power of unit tests a software developer can find defects quickly, avoid regression and speed up development time. In this talk I’ll show how to use the right unit testing tools and practices available that will help you get your C++ code under control and even test legacy code which no one ever want to touch.

1. C++ Unit testing
The good, the bad and the
ugly
Dror Helper | @dhelper | http://helpercode.com

2. Consultant @CodeValue
Developing software since 2002
Clean Coder & Test Driven Developer
Pluralsight author
https://www.pluralsight.com/authors/dror-helper
B: http://helpercode.com
T: @dhelper
About.ME

3. An ode to C++
Multi-paradigm Performance & Speed Truly multi-platform Plays well with others
Extendible and powerful Low level programming
My compiler compiled
your compiler’s compiler

4. “C makes it easy to shoot yourself
in the foot;
C++ makes it harder, but when you
do it blows your whole leg off.”
Bjarne Stroustrup

5. Avoid stupid
bugs
Early feedback
Avoid
Regression
Write
Sustainable,
manageable
code
Route to
modular OO
design
In code
documentation
Have you tried unit testing your code?

6. Definition: Unit Test (by me)
A method (code)
that tests specific functionality,
Has clear pass/fail criteria
and runs in isolation

7. This is a unit test (GTest)
TEST(MovieTests, WhatWouldTucoDo)
{
Charcter tuco;
tuco.SetHaveToShoot(true);
ASSERT_FALSE(tuco.GetTalk());
}

8. What you’ll need
Developer’s
Machine
• Unit testing framework
• Mocking framework
• Code coverage tool
• Other (IDE, Refactoring tools)
Continuous
Integration
• CI Server
• Build Agent(s)

9. Unit testing framework capabilities
Tests &
Fixtures
Assertio
ns
Test
Runners

10. C++ Unit Testing Frameworks
The Good
• Many choices
• Many Styles
The Bad
• Documentation may vary
• Not all maintained
The Ugly
• Deployment
• No Reflection…

11. * at least until C++/2020

12. C++ Unit Testing
Frameworks
GTest
MSTest
Catch
CppUnit
Boost.Test
DocTest
lest
xUnit++
Mettle
A Short, incomplete list…

13. Multiple asserts
• Lose information
• Complex tests
One assert per test
• Writing many tests for
the same scenario
• See Above
The multiple assertion dilemma

14. Innovation in C++
Enabling readable and maintainable tests
• Failures without exceptions
• Better failure messages
• Single, powerful assert
• Rethinking test fixture - Sections

15. 16
What is a “Mock”?
“mock objects are simulated objects that
mimic the behavior of real objects in
controlled ways”
[From Wikipedia]
I prefer to call them “Fakes”

16. Mocking frameworks responsibilities
1. Create Fake/Mock objects
2. Set behavior on fakes
3. Verify that methods were called

17. C++ Mocking Frameworks
The Good
• C++ has mocking frameworks
The Bad
• I meant a framework (at least until recently)
• Beware of dead projects
The Ugly
• Most one step better than hand rolled mocks
• Most are not AAA compliant

18. C++ Mocking
Frameworks
GMock
Trompeloeil
HippoMocks
FakeIt
*Based on my own experience

19. Don’t use obsolete tools!
1. Check when was the last commit!
2. How extensive is the documentation
C++ is changing and so should your testing framework

20. C++ Development in Windows
• Multi-platform – develop on windows, compile to run everywhere
• Remote debug/run on Linux (VS2017)
• Use test runner (or develop your own)
• Code coverage support

21. How to choose your unit testing tools
Multi-platform vs. mono-platform
Ease of use
What happens when test fails
Integration points
Runner Support
Ease of deployment
Personal taste

22. IN THIS WORLD THERE’S
TWO TYPES
OF PEOPLE MY FRIEND.
THOSE WITH UNIT TESTS
AND THOSE WHO BLAME.
WRITE UNIT TESTS!

23. Thank you
Dror Helper | @dhelper | http://helpercode.com