This document outlines the goals and key concepts of a training on property based testing (PBT). The goals are to understand best practices of PBT, formulate properties for pure functions, generate test data on the fly, and gain interest in learning more. It introduces PBT and the idea of specifying properties that functions should satisfy, having the testing tool generate test cases and shrink failing cases. It discusses tools available for PBT and hands-on practice writing a property. It concludes with practical advice on PBT and references for further information.

1. PropErty Based Testing
Enrique Paz @quiquepaz
Rolph de Ruiter
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2. Goals of the day
• Underestanding DOs and DON’Ts of PBT
• Formulating your own properties for pure functions
• Designing and generating test data sets on the fly
• And making you eager for more!
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3. Goals of the day
• Underestanding DOs and DON’Ts of PBT
• Formulating your own properties for pure functions
• Designing and generating test data sets on the fly
• And making you eager for more!
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4. Goals of the day
• Underestanding DOs and DON’Ts of PBT
• Formulating your own properties for pure functions
• Designing and generating test data sets on the fly
• And making you eager for more!
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5. Goals of the day
• Underestanding DOs and DON’Ts of PBT
• Formulating your own properties for pure functions
• Designing and generating test data sets on the fly
• And making you eager for more!
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6. Property Based Testing
Training Setup
• github.com/spilgames/PropEr@ErlangDCRB13
README.md
Makefile + rebar
src/ with source and properties
test/*_eunit.erl as test controllers
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7. Property Based Testing
The Idea
• What properties should hold?
• Properties document your code
• Properties generate the testcases
• Shrinking towards the smallest input that crashes
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8. Property Based Testing
The Idea
• What properties should hold?
• Properties document your code
• Properties generate the testcases
• Shrinking towards the smallest input that crashes
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9. Property Based Testing
The Idea
• What properties should hold?
• Properties document your code
• Properties generate the testcases
• Shrinking towards the smallest input that crashes
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10. Property Based Testing
The Idea
• What properties should hold?
• Properties document your code
• Properties generate the testcases
• Shrinking towards the smallest input that crashes
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11. Property Based Testing
Available Tools
• Available for multiple languages
• Open Source
• Trainings and support (at a price)
• Plenty of documentation
• Pulse for concurrency issues
• Using & contributing via Github
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12. Hands On!
A Property
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13. Conclusions
The Stuff You’re Supposed To Remember
• Start with simple tests
• Think properties
• Always test your generators first
• Test a reasonable success/error rate
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14. Conclusions
A Practical View
• Property Driven Development is not a thing
Thinking properties is hard
Refactoring properties is hard
Manual basic testcases help you think
• Naming is essential
• Avoid reimplementating + comparing
• PBT finds stuff you’d never think of
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15. Conclusions
A Practical View
• Property Driven Development is not a thing
Thinking properties is hard
Refactoring properties is hard
Manual basic testcases help you think
• Naming is essential
• Avoid reimplementating + comparing
• PBT finds stuff you’d never think of
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16. Conclusions
More Info
• PropEr @github
• PropEr Docs
• Quickcheck For Erlang
• Concuerror @github
• Concuerror Presentation
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17. Conclusions
Questions?
Leave us feedback! http://spkr8.com/t/28341
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