TDD IN AN IoT WORLD Charles Korn 1 IoT? 2 What is TDD? 3 - PowerPoint PPT Presentation

TDD IN AN IoT WORLD Charles Korn 1

IoT? 2

What is TDD? 3

Test-driven development 4

Test-driven development Test-driven design 5

It’s not just about testing your code 6

It’s also about designing your code to be testable 7

CODE THAT IS DESIGNED TO BE EASY TO TEST Image credit: weedist.com 8

Code that is easy to test is: small simple has a single responsibility 9

Clean code is: small simple has a single responsibility 10

But how? 11

Red Green Refactor 12

Image credits: unicornsrule.com and Nicolò Bertoncin 13

Development environment 14

≈ ≈ ≉ Image credits: Michael Bundscherer, Kevin Kwok, Nicolò Bertoncin, R fl or 15

Hardware constraints 16

Long write-run-debug cycle 17

12 9 6 3 0 Host Target 18

Might not have target hardware 19

Development and production environment di ff erences Hardware constraints Long write-run-debug cycle Target hardware availability 20

Red Green Test on Refactor target hardware Image credits: Kevin Kwok and Nicolò Bertoncin 21

Compile Flash Run Compile Flash Run First 50% of tests Second 50% of tests 22

Lots of low-level interactions with hardware 23

Avoid direct interactions with hardware (or: use good abstractions) 24

PINA |= (1 << LED_PIN) or turnOn(LED_PIN) expect(PINA & 0x04 == 1) or expect(getState(LED_PIN) == ON) 25

Performance concerns 26

Image credit: scmp.com 27

IT’S A TRAP! Image credit: Lucas fi lm 28

Know what ‘good enough’ looks like Know why it’s required Have a repeatable way to measure it The tests can help you 29

C and C++ 30

Image credit: memecenter.com 31

Link-time fakes 32

Function pointers 33

Virtual classes 34

Image credit: XKCD 35

Go forth and TDD 36

Before I go… 37

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https://github.com/charleskorn/stm32f4-project-template Image credit: blog.tkjelectronics.dk 40

TDD for circuit design 41

THANK YOU Charles Korn charleskorn.com