Test-Driven Development
in C++
Dresden, Nov 13, 2014
Peter Steinbach
Scionics Computer Innovation GmbH
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How people code
First
Idea(s)
Second
Coffee & Code
Third
Launch To Mars
Validate
Unexpected Result!
Compile and run?
Build and Fix Software Model
Code in Science
Reproducibility?
Preclinical Cancer Research
Preclinical Cancer Research
Scientific Computing?
Test-Driven
Development
How?
Live Demo
Writing a vector with a norm!
Classical Approach
Unit Test
method to test smallest testable part of an application
Test Suite
sequence of Unit Tests that validate the same entity
Test Fixture
called before/after execution of unit test to setup or tear down test environment
What to test?
Let's play!
Test the Contract!
- pre-condition
(type and content of input data)- service it provides
(the responsibility it has)- post-condition
(type and content of output data)
Exercise?
cyber-dojo.org
Summary
- incremental design
- developer confidence
- less feature envy
- reproducibility included
- documentation included
- continuous integration
- ...
- code is less bug free
- human interaction?
- dead code?
- can be misleading!
- hinders good design
- ...
Ongoing Discussion!
Tools
Standard Libraries
Standard xUnit Approach
State-of-the-Art Libraries
Meta-Programming
//test inside the code in C++11 or with BOOST_STATIC_ASSERT in C++03
std::static_assert( sizeof(small_t) < sizeof(large_t) );
#include "boost/mpl/assert.hpp"
BOOST_MPL_ASSERT( sizeof(small_t) < sizeof(large_t) );
BOOST_MPL_ASSERT_MSG( sizeof(small_t) < sizeof(large_t) ,
MESSAGE_THAT_WILL_BE_PRINTED);
BOOST_MPL_ASSERT_NOT(( boost::is_same< small_t,large_t > ));
BOOST_MPL_ASSERT_RELATION( sizeof(small_t), <, sizeof(large_t) );
Summary
- real-world test-driven development has a learning curve
- creates confidence and reproducibility
- good software design step-by-step
- a lot of tools available
- no silver bullet!
Thank you for your attention!
Literature
- Robert C. Martin, Agile Software Development: Principles, Patterns and Practices. Pearson Education, 2002
- Kent Beck, Test-Driven Development by Example. Addison-Wesley Longman, 2002
- Overload Magazine, Issue 122
- "Modern C++ Testing" by Phil Nash (author of catch)