Cracking the code review at SpringIO 2024
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Paco van Beckhoven's presentation discusses the importance of code reviews in improving code quality and reducing the cost of fixing bugs. He emphasizes systematic evaluation, clear communication, automated tools, and adherence to coding standards to enhance the review process. The talk also highlights the critical components of effective pull requests and suggests methods for gathering and providing feedback during code reviews.
![@DevPaco #SpringIO24
ConvenAonal Comments
• <label> [decoraEons]: <subject>
• [discussion]
• hRps://convenEonalcomments.org/](https://image.slidesharecdn.com/crackingthecodereviewspringio-240603094724-e3c2ad87/85/Cracking-the-code-review-at-SpringIO-2024-43-320.jpg)
![@DevPaco #SpringIO24
One way or another
return list.filter(address -> address != null);
Example.java:[22,33] Note: [Refaster Rule] NullRules.NonNullFunc3on: Refactoring opportunity
[ERROR] (see h,ps://error-prone.picnic.tech/refasterrules/NullRules#NonNullFunc3on)
[ERROR] Did you mean ‘list.filter(Objects::nonNull);'?
return BigDecimal.valueOf(0);
[INFO] Example.java:[12,30] [Refaster Rule] BigDecimalRules.BigDecimalZero: Refactoring opportunity
(see https://error-prone.picnic.tech/refasterrules/BigDecimalRules#BigDecimalZero)
Did you mean 'return BigDecimal.ZERO;'?](https://image.slidesharecdn.com/crackingthecodereviewspringio-240603094724-e3c2ad87/85/Cracking-the-code-review-at-SpringIO-2024-51-320.jpg)
![@DevPaco #SpringIO24
Broken logging/formaQng
Example.java:[21,27] error: [FormatString] extra format arguments: used 0, provided 1
[ERROR] (see h,ps://errorprone.info/bugpa,ern/FormatString)
return "{}".forma,ed("test");](https://image.slidesharecdn.com/crackingthecodereviewspringio-240603094724-e3c2ad87/85/Cracking-the-code-review-at-SpringIO-2024-52-320.jpg)
![@DevPaco #SpringIO24
Broken asserAons
[ERROR] MyTest.java:[73,14] error: [CheckReturnValue] The result of `assertThat(...)` must be used
[ERROR] (see h,ps://errorprone.info/bugpa,ern/CheckReturnValue)
[ERROR] Did you mean 'assertThat(somePojo.getId().equals("expectedId")).isTrue();'?
assertThat(somePojo.getId().equals(”expectedId"));](https://image.slidesharecdn.com/crackingthecodereviewspringio-240603094724-e3c2ad87/85/Cracking-the-code-review-at-SpringIO-2024-53-320.jpg)
![@DevPaco #SpringIO24
Improve readability
StripeWebhookController.java:[90,2] Note: [SpringMvcAnnota3on] Prefer the conciseness of
`@{Get,Put,Post,Delete,Patch}Mapping` over `@RequestMapping`
(see h,ps://error-prone.picnic.tech/bugpa,erns/SpringMvcAnnota3on)
Did you mean '@PostMapping(value = URL_WEBHOOK_USER_V1)'?
@RequestMapping(
value = URL_WEBHOOK_USER_V1,
method = RequestMethod.POST
)](https://image.slidesharecdn.com/crackingthecodereviewspringio-240603094724-e3c2ad87/85/Cracking-the-code-review-at-SpringIO-2024-54-320.jpg)
![@DevPaco #SpringIO24
Configure code style
• formatting issues
• coding rule violations
• Integrates with most editors
Example.java:[22,5] (naming)
ConstantName: Name ‘defaultExtension'
must match pa,ern '^[A-Z][A-Z0-9]*(_[A-Z0-
9]+)*$’.
Example.java:[59,3] (coding)
Declara3onOrder: Sta3c variable defini3on
in wrong order.](https://image.slidesharecdn.com/crackingthecodereviewspringio-240603094724-e3c2ad87/85/Cracking-the-code-review-at-SpringIO-2024-61-320.jpg)
Cracking the code review at SpringIO 2024
- 1. Paco van Beckhoven @DevPaco Cracking the Code Review: From Guesswork to Automated Guidance
- 2. @DevPaco #SpringIO24 Paco van Beckhoven - 10+ years of experience - So3ware engineer - @ Hexagon’s Innova/on Hub - I ❤ Code quality About me
- 4. @DevPaco #SpringIO24 Cost of fixing a bug h"ps://www.func-onize.com/blog/the-cost-of-finding-bugs-later-in-the-sdlc
- 5. @DevPaco #SpringIO24 Cost of fixing a bug h"ps://www.func-onize.com/blog/the-cost-of-finding-bugs-later-in-the-sdlc Code reviews
- 6. @DevPaco #SpringIO24 Code review Code review “A code review is a systematic evaluation of source code by others, intended to identify errors, foster learning among developers and improve code quality”
- 7. @DevPaco #SpringIO24 Code review Code review “A code review is a systemaEc evaluaEon of source code by others, intended to iden9fy errors, foster learning among developers and improve code quality” Code quality “Code quality refers to the extent to which code is maintainable, readable, efficient, and robust, following established coding conven9ons and best prac9ces.”
- 9. @DevPaco #SpringIO24 Pull requests h"ps://www.atlassian.com/blog/bitbucket/5-pull-request-must-haves
- 10. @DevPaco #SpringIO24 Version Control Systems
- 15. @DevPaco #SpringIO24 Review friendly pull requests Changes are ✅ Concise ✅ Focused ✅ Tested
- 17. @DevPaco #SpringIO24 What makes a good Atle h,ps://www.conven3onalcommits.org/
- 18. @DevPaco #SpringIO24 The DescripAon • Context • What changed • Why • Examples • Keep it concise and readable
- 20. @DevPaco #SpringIO24 Review your own code! • Different perspecEve • Add context to smaller changes • Highlight important parts • Ask specific quesEons
- 21. @DevPaco #SpringIO24 Asking for reviews
- 22. @DevPaco #SpringIO24 Asking for reviews • Diffusion of responsibility • Context • Deadline
- 23. @DevPaco #SpringIO24 • Diffusion of responsibility • Context • Deadline Asking for reviews help
- 26. @DevPaco #SpringIO24 Endless discussions • Pick your baRles • Take it offline • “As discussed offline; we decided to go for soluEon x because of y”
- 27. @DevPaco #SpringIO24 Be grateful 🙏 “Fixed” “Thanks, learned something new about the API, it's fixed now” ➡
- 28. @DevPaco #SpringIO24 Giving reviews • Don’t wait too long • Taking responsibility
- 29. @DevPaco #SpringIO24 Giving reviews • Don’t wait too long • Taking responsibility
- 30. @DevPaco #SpringIO24 Get the context • Read the description • Check the spec • Existing comments
- 31. @DevPaco #SpringIO24 How to review? • Design • FuncEonality • Complexity • Tests • Style / Documenta/on
- 32. @DevPaco #SpringIO24 Tool assisted reviews
- 33. @DevPaco #SpringIO24 Use your editor
- 34. @DevPaco #SpringIO24 Use your editor
- 35. @DevPaco #SpringIO24 Use your editor
- 36. @DevPaco #SpringIO24 Use your editor
- 37. @DevPaco #SpringIO24 Use your editor
- 38. @DevPaco #SpringIO24 Use your editor
- 39. @DevPaco #SpringIO24 AI powered tools CodeRabbit - hLps://coderabbit.ai/ Bito - hLps://bito.ai/ Sourcery - hLps://sourcery.ai/
- 40. @DevPaco #SpringIO24 WriAng a good comment • You -> We • Statements -> QuesEons “Why did we chose y? I understood x is more ac/vely maintained”
- 41. @DevPaco #SpringIO24 Writing a good comment • Be specific • Re-read your comment • Try to provide an alternaEve/soluEon
- 43. @DevPaco #SpringIO24 ConvenAonal Comments • <label> [decoraEons]: <subject> • [discussion] • hRps://convenEonalcomments.org/
- 47. @DevPaco #SpringIO24 Bikeshedding / Law of triviality “People within an organizaEon commonly give dispropor9onate weight to trivial issues” – Parkinson, 1957
- 48. @DevPaco #SpringIO24 Bikeshedding / Law of triviality “People within an organizaEon commonly give dispropor9onate weight to trivial issues” – Parkinson, 1957
- 50. @DevPaco #SpringIO24 Error-prone Detects common programming mistakes at compile-9me and provides automated fixes ❤
- 51. @DevPaco #SpringIO24 One way or another return list.filter(address -> address != null); Example.java:[22,33] Note: [Refaster Rule] NullRules.NonNullFunc3on: Refactoring opportunity [ERROR] (see h,ps://error-prone.picnic.tech/refasterrules/NullRules#NonNullFunc3on) [ERROR] Did you mean ‘list.filter(Objects::nonNull);'? return BigDecimal.valueOf(0); [INFO] Example.java:[12,30] [Refaster Rule] BigDecimalRules.BigDecimalZero: Refactoring opportunity (see https://error-prone.picnic.tech/refasterrules/BigDecimalRules#BigDecimalZero) Did you mean 'return BigDecimal.ZERO;'?
- 52. @DevPaco #SpringIO24 Broken logging/formaQng Example.java:[21,27] error: [FormatString] extra format arguments: used 0, provided 1 [ERROR] (see h,ps://errorprone.info/bugpa,ern/FormatString) return "{}".forma,ed("test");
- 53. @DevPaco #SpringIO24 Broken asserAons [ERROR] MyTest.java:[73,14] error: [CheckReturnValue] The result of `assertThat(...)` must be used [ERROR] (see h,ps://errorprone.info/bugpa,ern/CheckReturnValue) [ERROR] Did you mean 'assertThat(somePojo.getId().equals("expectedId")).isTrue();'? assertThat(somePojo.getId().equals(”expectedId"));
- 54. @DevPaco #SpringIO24 Improve readability StripeWebhookController.java:[90,2] Note: [SpringMvcAnnota3on] Prefer the conciseness of `@{Get,Put,Post,Delete,Patch}Mapping` over `@RequestMapping` (see h,ps://error-prone.picnic.tech/bugpa,erns/SpringMvcAnnota3on) Did you mean '@PostMapping(value = URL_WEBHOOK_USER_V1)'? @RequestMapping( value = URL_WEBHOOK_USER_V1, method = RequestMethod.POST )
- 55. @DevPaco #SpringIO24 Tips • Test the rules on your codebase and choose those that match your team’s style best • Some rules might have some issues with tools like lombok • Make sure to ignore generated code
- 56. @DevPaco #SpringIO24 OpenRewrite • By Moderne • Large set of recipes • Migra/ng Java version • Spring upgrades • Moving to AssertJ • Many more…. assertEquals(1, currentSubs.size()); assertThat(currentSubs.size()).isEqualTo(1); ⬇ assertThat(currentSubs).hasSize(1); ⬇ https://www.moderne.io/blog/stop-breaking-ci-annotate-prs-with-openrewrite-recipe-fixes-as-quality-gate
- 57. @DevPaco #SpringIO24 FormaQng • The more opinionated the less room for discussion • Automatically enforceable • Don’t deviate too much from industry standards
- 58. @DevPaco #SpringIO24 spring-javaformat • hRps://github.com/spring-io/spring-javaformat • AutomaEcally format your code from CLI • It is effecEvely limited to adding or removing whitespace and line feeds • AddiEonal Checkstyle plugin
- 59. @DevPaco #SpringIO24 google-java-format • Implements the Google Java Style Guide • Integrates with most editors • No formaRer will be perfect
- 60. @DevPaco #SpringIO24 fmt-maven-plugin • AutomaEcally format your code from CLI • AutomaEcally fail on formaing issues
- 61. @DevPaco #SpringIO24 Configure code style • formatting issues • coding rule violations • Integrates with most editors Example.java:[22,5] (naming) ConstantName: Name ‘defaultExtension' must match pa,ern '^[A-Z][A-Z0-9]*(_[A-Z0- 9]+)*$’. Example.java:[59,3] (coding) Declara3onOrder: Sta3c variable defini3on in wrong order.
- 62. @DevPaco #SpringIO24 • Enforcing Architecture guidelines and naming convenEons • Also used for Spring Modulith
- 63. @DevPaco #SpringIO24 Architecture checks @ArchTest sta3c final ArchRule layer_dependencies_are_respected = layeredArchitecture().consideringAllDependencies() .layer("Controllers").definedBy("com.tngtech.archunit.example.layers.controller..") .layer("Services").definedBy("com.tngtech.archunit.example.layers.service..") .layer("Persistence").definedBy("com.tngtech.archunit.example.layers.persistence..") .whereLayer("Controllers").mayNotBeAccessedByAnyLayer() .whereLayer("Services").mayOnlyBeAccessedByLayers("Controllers") .whereLayer("Persistence").mayOnlyBeAccessedByLayers("Services");
- 64. @DevPaco #SpringIO24 Naming conventions @ArchTest sta3c ArchRule interface_names = classes().that().areInterfaces().should().haveNameMatching(".*Interface"); @ArchTest static ArchRule controllers_should_be_suffixed = classes() .that().resideInAPackage("..controller..") .or().areAnnotatedWith(MyController.class) .or().areAssignableTo(AbstractController.class) .should().haveSimpleNameEndingWith("Controller");
- 65. @DevPaco #SpringIO24 Tips • Check the large set of predefined rules • Capture common mistakes • Create a shared module with rules
- 66. @DevPaco #SpringIO24 Preferred order of tools • Compile Eme tools with suggesEons/fixes • google-java-format with spo/fy plugin • error-prone • Compile Eme tools • Checkstyle • Sonar • Tests
- 67. @DevPaco #SpringIO24 Introducing tools to your organisation • Start small • Involve the team • Use sample MRs to discuss rule sets • Centralize configuraEon • Use a parent-pom
- 68. @DevPaco #SpringIO24 Conclusion • Write descripEve pull requests and review them yourself • Be specific in your communicaEon • Be friendly and find posi/ve things • Use VCS feature/your editor to help you review •Stop bikeshedding, start automa4ng!
- 69. @DevPaco #SpringIO24 Thank you! h,ps://errorprone.info/ and h,ps://error-prone.picnic.tech/ Catches common programming mistakes at compile-3me h,ps://github.com/google/google-java-format h,ps://github.com/spo3fy/fmt-maven-plugin Automated formazng of your code h,ps://www.archunit.org/ Unit test your Java architecture h,ps://github.com/spring-io/spring-javaformat Spring’s formazng and checkstyle plugins h,ps://google.github.io/eng-prac3ces/ Google best prac3ces on code reviews