Improve your code with Lint checks for Kotlin

The linter tool has been around for a long time, and sometimes we forget it exists or we just use it as it comes out of the box.
But there is so much more we can do to leverage this tool, and tailor it to our needs.
From finding vulnerabilities in our code, all the way to promoting company wide guidelines.

Transcript

1. Improve your code with Lint checks for Kotlin Emma Tresanszki
6. 1978 1979
7. 1978 1979 Android Lint 1.0 released in 2011
8. Android Lint Philosophy #1 “False positives are better than false negatives.” #2 Focus on Android issues - Leave general coding issues to the IDE
9. How to use it ? IDE Gradle - On the fly - Run inspections by name - Command line - xml/html reports
11. Example
13. Goal • Run lint on every build • If there are any new lint issues, break the build • Get to zero unchecked lint errors and warnings
15. ./gradlew lint Shock option
16. ./gradlew lint Shock option Baby steps
17. lint.xml
18. lint.xml
19. Configuration
20. Configuration ignoreTestSources
21. Be specific !
22. @suppressing stuff around • Sometimes you just don’t care • @Unused in library • You don’t want to break the build
23. @suppressing stuff around • Sometimes you just don’t care • @Unused in library • You don’t want to break the build
24. @suppressing stuff around
25. Baseline
26. @Annotations ~= hints
27. @Annotations ~= hints
28. @Annotations ~= hints
29. What about Kotlin modules ?
30. Supported lint checks Starting with the Android Gradle Plugin 3.1.0 you can apply Android Lint to Java / Kotlin modules.
31. File -> Preferences -> Editor -> Inspections What about Kotlin modules ?
32. What about Kotlin modules ? File -> Preferences -> Editor -> Inspections
33. What about Kotlin modules ? File -> Preferences -> Editor -> Inspections
34. What about Kotlin modules ? File -> Preferences -> Editor -> Inspections
35. What about Kotlin modules ? Android Gradle Plugin 3.4.0 +
36. Other options
37. Other options
38. Write your own Lint rule
39. UAST Universal Abstract Syntax Tree - UElement -> root of everything - UFile -> Compilation unit - UClass -> A class declaration - UMember - UField - UMethod - ...
42. UastScanner Convenience callbacks to check - Any calls to a method of a given name - Any instantiations of a given class - Any subclasses or sub interfaces - Any Android resource reference - Annotation usages - Any AST nodes by type - ...
43. ISSUES REGISTRIES DETECTORS IMPLEMENTATIONS
45. New module
46. IMPLEMENTATIONS
47. ISSUES
48. ISSUES
49. DETECTORS
50. DETECTORS
51. REGISTRIES
52. Trigger the custom linting
53. Testing
55. Testing issue detection
56. Testing issue detection
57. Testing
58. Running the tests ./gradlew clean build test
59. Quickfixes Automatic fix action in IDE - Descriptor of action to address the problem
60. Quickfixes Automatic fix action in IDE
61. Quickfixes
63. This presentation will soon be available on the droidcon London website at the following link https:/ /skillsmatter.com/conferences/11785-droidcon-lo ndon-2019#skillscasts @EmmaTresanszki https:/ /github.com/emmaChristine/DCLondon
64. References 1. https:/ /developer.android.com/studio/write/lint 2. https:/ /en.wikipedia.org/wiki/Lint_(software) 3. https:/ /github.com/pinterest/ktlint/tree/master/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/st andard 4. https:/ /medium.com/@vanniktech/running-lint-on-java-kotlin-modules-55b747d0e5f3 5. https:/ /www.bignerdranch.com/blog/building-custom-lint-checks-in-android/ 6. https://www.youtube.com/watch?v=p8yX5-lPS6o&feature=youtu.be&t=1353 7. https://www.youtube.com/watch?v=ffH-LD5uP4s 8. https://developer.android.com/studio/write/lint#manuallyRunInspections 9. https://medium.com/@intelia/getting-the-most-out-of-android-lint-6df05a7ab054 10. https://tech.yplanapp.com/2016/08/10/android-lint/ 11. https://www.youtube.com/watch?v=ffH-LD5uP4s 12. Photo by Kelly Sikkema on Unsplash Photo by Joanna Kosinska on Unsplash