Increase testability with code seams
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This document discusses ways to increase testability through code seams. It recommends separating code into functional and non-functional pieces, and extracting the functional pieces. This allows the functional code to be tested in isolation without external dependencies. Specific techniques mentioned include peeling away non-functional layers and slicing functional logic from surrounding code. Examples show how to make code more deterministic and remove reliance on global state, dates, and other uncontrollable variables to improve testability.
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Increase testability with code seams
- 1. Increase Testability with Code Seams @LlewellynFalco
- 2. SEAMS
- 5. Why is Testing Hard? 1. Setup 2. Lot’s of paths 3. Global state 4. Lot’s of clutter 5. Environment 6. Uncontrollable Variables 7. UI 8. Money 9. Dates 10.Mobile 11.Database 12.Integration 13.Wait Times 14.XPath 15.Finding Elements 16.Timing 17.Failure cases
- 6. Automated checking is a tactic of testing, and can have considerable value... …Checking through an API beneath the GUI level can be particularly useful. In designing such low-level checks, programmers and testers can profitably work together. We are more doubtful of automated checking at the GUI level. GUIs are notoriously fussy.
- 7. CASE #3: Automated checking. We wanted to demonstrate full-on automated checking, while at the same time staying with the FocusWriter example. FocusWriter does not provide an API for testing, which required us to automate through the GUI, and so the headaches began.
- 12. BYPASS EVERYTHING https://github.com/EditProfile/ ?data={“Name”: “Llewellyn Falco”, “photo”:”http://”….}
- 14. TESTING EDIT PROFILE By.xpath("//div[@class='canvas- graph']//div[contains(text(),Location)][input]/following-sibling::h4”)
- 16. DarkFunction Editor Test 1. Open df editor 2. Find File -> Find New -> Find Animation set 3. Navigate to github -> dark function editor -> Testing Resources -> StarWarsImages -> SWAII.sprites 4. Open 5. Add animation 6. Add animation (1) 7. Add animation (2) 8. Rename animation 1 -> animation a 9. add animation 10 . find animation 3 confirm exists.
- 18. DarkFunction Unique Name Given animation names: animation, animation 2 When I ask for a new name Then I get animation 3
- 19. DarkFunction Editor Test 1. Open df editor 2. Find File -> Find New -> Find Animation set 3. Navigate to github -> dark function editor -> Testing Resources -> StarWarsImages -> SWAII.sprites 4. Open 5. Add animation 6. Add animation (1) 7. Add animation (2) 8. Rename animation 1 -> animation a 9. add animation 10 . find animation 3 confirm exists.
- 21. Functional Deterministic All inputs in All results out
- 22. NON-Functional Get inputs as needed (global state, file, database…) Result vary (dates, random, environment) Store results (global, disk, database, transient)
- 23. public double calculate(double amount) { int step1 = (int) (amount * 2); double step2 = step1 * 1.5; return step2; } All results out All inputs in Deterministic
- 24. public int Advance() { return steps++; } All inputs in?
- 25. All inputs in? Deterministic? public int age(DateTime birthDate) { var timeSpan = DateTime.Now - birthDate; var age = DateTime.MinValue + timeSpan; return age.Year-1; }
- 26. public void saveFile(Person info, string fileName) { File.WriteAllText(fileName, info.ToString()); } All results out?
- 27. WHY FUNCTIONAL IS EASIER FOR TESTS Unit Test Production Code Do Verify
- 28. WHY FUNCTIONAL IS EASIER FOR TESTS Unit Test Production Code Do Verify Functional Harness
- 29. public static Output function(inputs)
- 30. STEPS 1. Determine functional parts 2. Separate 3. Extract 4. Compare against intention
- 35. Why is Testing Hard? 1. XPath 2. Finding Elements 3. Global state 4. Dates 5. Failure cases 6. Wait Times 7. Mobile 8. Setup 9. Lot’s of paths 10.Environment 11.Uncontrollable Variables 12.UI 13.Money 14.Dates 15.Database 16.Integration 17.Finding Elements 18.Timing
Editor's Notes
- git checkout 8918da8
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