Automated Testing but like for PowerShell (April 2012)
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This document discusses automated testing for PowerShell. It covers different types of automated tests like unit tests, integration tests, and behavior driven development. It introduces Pester, a framework for writing BDD-style tests in PowerShell. While Pester allows writing tests, it does not enable mocking or stubbing. The document demonstrates how to perform unit testing, stubbing, and mocking in PowerShell by overwriting functions and setting expectations and behaviors.
![Test Automation
• Test automation is the use of software to
control the execution of tests, the comparison
of actual outcomes to predicted outcomes,
the setting up of test preconditions, and other
test control and test reporting
functions.[1] Commonly, test automation
involves automating a manual process already
in place that uses a formalized testing process.
• -Wikipedia](https://image.slidesharecdn.com/automatedtestingforpowershell-140904115103-phpapp01/85/Automated-Testing-but-like-for-PowerShell-April-2012-6-320.jpg)
Automated Testing but like for PowerShell (April 2012)
- 1. Automated Testing but like For PowerShell Rob Reynolds
- 3. Who am I? Who cares… • Rob Reynolds • Technical Lead for VML • OSS – Chocolatey / Chuck Norris Framework / NuGet – Various contributions to other projects • ferventcoder – twitter, gmail, you name it • ferventcoder.com / Devlicio.us • Automated Testing for 8 years
- 4. Topics d • Automated Testing… – Integration Testing – Mocking – Unit Testing • Behavior Driven Development… – What does it all mean? • ..but like for PowerShell? – Pester Entire presentation w/examples: http://bit.ly/powershellbdd
- 6. Test Automation • Test automation is the use of software to control the execution of tests, the comparison of actual outcomes to predicted outcomes, the setting up of test preconditions, and other test control and test reporting functions.[1] Commonly, test automation involves automating a manual process already in place that uses a formalized testing process. • -Wikipedia
- 7. So what is test automation? • Making executable tests to determine your software works appropriately
- 8. Fallacies of automated testing • “Automated tests will prove the absence of bugs” • “’Unit’ testing is easy” • “One class – one test class” • “Testing takes little time”
- 10. Why do automated testing? • “We never touch that piece of code. A guy wrote it a long time ago and he’s not here anymore. It just works.” – Translation “We have no idea WTF it does and have no test automation on it to help us figure it out.”
- 11. So why do automated testing? • Maintenance – change is a constant • Feedback cycles • Scenarios / edge cases • Gives you confidence in the code – Works appropriately
- 12. What are the types of automated tests? • White box (MSTest / Nunit / xUnit / MbUnit) – Unit – Integration • Functionality – Groups of functionality • Database Tests • Black box (FitNesse) – End 2 End – System Integration Testing • Performance testing
- 13. What are the types of automated tests? • White box (MSTest / Nunit / xUnit / MbUnit) – Unit – Integration • Functionality – Groups of functionality • Database Tests • Black box (FitNesse) – End 2 End – System Integration Testing • Performance testing
- 14. What are the types of automated tests? • White box – Unit – Integration • Functionality – Groups of functionality • Database Tests Why do we categorize? Is it because we are just developers and everything has a place?
- 15. Reasons for categorization • Feedback cycles • Maintenance • “The more units put into something the greater the feedback cycle and the less maintainable the test.”
- 16. Unit Testing • Test a “unit” of something • But WTF is a unit? – A near religion around this • For purposes of discussion a unit is one class / sometimes one method in code
- 17. Integration Testing • Integration – Functionality – Groups of functionality – Database Tests “Anything that tests more than one unit as part of the same test is an integration”
- 18. But wait, couldn’t that mean all tests are integration?
- 19. Integration Testing • Integration – Functionality – Groups of functionality – Database Tests “Anything that tests more than one unit as part of the same test is an integration” Yes, most tests we write are a blend of unit and integration but we strive for unit testing
- 20. Demo
- 21. Where does Mocking come in?
- 22. Where does mocking come in? • Fakes, mocks, stubs – oh my! – Dummies - objects are passed around but never used – Fake - working implementations with possible shortcuts – Stubs - provide canned answers (answer state questions) – Mocks - objects with you can set expectations and verify behavior on • Known as test doubles
- 23. Test Doubles – is it okay to blend? • Most of us never write a true stub/fake/mock/etc but something that blends ideas from each of these
- 25. This is not BDD… • ...but the style of writing for your tests in a natural language • BDD can be a religious battle and this talk is not about that (check out Dan North for more info) • Describe behaviors and interactions • Think not about “tests” but about behaviors and specifications
- 26. Demo
- 27. …but like for PowerShell
- 28. Meet Pester • https://github.com/scottmuc/Pester • BDD style of test writing
- 29. Demo
- 30. But is Pester enough? • Does not get you to unit testing alone • Does no mocking/stubbing
- 31. How to get there • A little ingenuity • Maybe a mocking/stub framework for PowerShell in the future – what would you name it? – PowerMock? – PSomething – PShellshock
- 32. PowerShell Unit Testing • A PowerShell unit is a function • Functions can be overwritten by scoping a function of the same name
- 33. PowerShell Stubbing • Functions can be overwritten by a function of the same name and parameters • This allows you to interrupt and stub the functionality • “I want behavior verification. I want my mock”
- 34. PowerShell Mocking • After you have implemented the stubs you allow different behaviors to be returned through conventional properties and flags
- 35. Demo
- 36. Questions? • ferventcoder – twitter, gmail, etc • Pester – https://github.com/scottmuc/Pester#readme • Chocolatey – http://chocolatey.org • Mocks aren’t stubs - http://martinfowler.com/articles/mocksArentS tubs.html