1.
Who is Lars Thorup?● Software developer ● Web: C# and JavaScript ● Embedded C++ for several devices using agile and automated testing● Coach: Teaching agile and automated testing● Advisor: Assesses software projects and companies● Founder and CEO of BestBrains and ZeaLake

2.
Agenda● What is automated testing?● Unity, test framework for embedded C● Code example● Why should we write automated tests?● Questions

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What is automated testing?● Developers write test ● Automated execution of all programs test programs

4.
The Unity testing framework● Small memory footprint ● Many test functions ● ASSERT_TRUE● Pure C ● FAIL ● ASSERT_EQUAL● Optional tools to generate ● ASSERT_WITHIN test runners automatically ● ASSERT_BITS ● ASSERT_NOT_NULL● Alternatives in C++ ● ASSERT_MEMORY ● CppUnit ● Google Test

5.
How do we handle dependencies?● The flow example ● a flow sensor ● generates pulse counts proportional to actual flow ● calculate average flow rate with regular intervals● The dependencies in the flow example ● the sensor creating the pulse interrupt ● recurring timer event ● thread safe counting● Decouple the dependencies ● Pulse: provide a callback to the FlowSensor component ● Timer and Counting: inject components into the Flow component● flow.c

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Dependencies, on device main.c Listen GetRate flowSensor.c flow.c Pulse GetTime timerImpl.c Increment counterImpl.c

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Dependencies, in test flowTest.c Pulse GetRate flow.c SetTime GetTime timerStub.c Increment counterImpl.c

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Strategy for testing embedded software● Continuous Integration ● Automate build and test execution ● On desktop, simulator and/or the device● Break dependencies ● Hardware Abstraction Layer ● Simulate time measurements and timer events ● Standardize on frequently used stubs ● Use mock objects for testing protocols● Dependency injection ● Link time, where possible ● Run time, using function pointers, where necessary

9.
Why should we write unit tests?● Speed up development ● Because of all the things we no longer have to waste time on ● Test Driven Development vs Debug Later Programming ● Avoid piling up technical dept (manual testing, bug fixing) ● Typing code is not where the bottleneck is● Find bugs faster ● Trivial bugs found immediately ● QA can do exploratory testing earlier and more extensively● Prevent bugs from reappearing ● Never fix a bug until we have a failing test● Improve the software design ● Loose coupling is required to write tests

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Links to further resources● List of testing tools for C and C++ ● http://www.opensourcetesting.org/unit_c.php● Book ● http://pragprog.com/titles/jgade/test-driven-development-for- embedded-c● Experiement on the benefits of TDD ● http://www.infoq.com/news/2009/03/TDD-Improves-Quality● Meetup groups ● http://www.meetup.com/Test-Driven-Developers-Bay-Area/

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Questions