Error Prone Support workshop - internal conference

-

1. 1

2. 2
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality1
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic

3. 3
Understanding code
“developers on average spend as
much as 58% of their time
comprehending existing source code”
- Felienne Hermans

4. 4

5. 5
Code reviews and discussions

6. 6

7. 7
Tools
Google/google-java-format
Reformats Java source code to comply
with Google Java Style.
checkstyle/checkstyle
Helps programmers write Java code
that adheres to a coding standard.
spotbugs/spotbugs
A tool for static analysis to look
for bugs in Java code.
SonarSource/sonarqube
Continuous Inspection.

8. 8
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality1
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic

9. 9
Open-source static analysis
Compiler plugin
500+ Error Prone checks
Complex
Error Prone
Google/error-prone
Catch common Java mistakes
as compile-time errors

10. 10
Refaster
Examples from: http://errorprone.info/docs/refaster
Define refactorings with templates.
becomes
becomes

11. 11
Demo
Let’s demonstrate!
https://github.com/rickie/error-prone-demo

12. 12
Maven profile 1

13. 13
Maven profile 2

14. 14
Demo
Let’s demonstrate!
https://github.com/rickie/error-prone-demo

15. 15
Bug patterns
https://errorprone.info/bugpatterns

16. 16
Error Prone as superpower

17. 17

18. 18
Error Prone as superpower
Input:
Output:

19. 19
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality1
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic

20. 20
Picnic open-sourced: Error Prone Support!
900+ Refaster rules
40+ Error Prone bug checks
Picnic-opinionated set of rules
Migrations
https://error-prone.picnic.tech

21. 21
Picnic’s Error Prone Support
Running Refaster rules
Test support
Improved reporting
Documentation

22. 22
Error Prone Support website
https://error-prone.picnic.tech

23. 23
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic
1

24. 24
Deep dive Refaster
-Background information

-Goals

-How does Refaster work?

-Advanced features

25. 25
Refaster
-2015 - Louis Wasserman (source)

-Two tools

-Closed source

26. 26

27. 27
Deep dive Refaster
Goals of Refaster (source):
-Scalability
-Expressivity
-Usability
When to use Refaster? (docs)

-Method A to method B.

-Migrate a fluent sequence of method invocations to some other
pattern.

-Migrate a sequence of consecutive statements to an alternative.

28. 28
Running Refaster

29. 29
Running Refaster - The Picnic Way
Link to an example configuration in Error Prone Support

30. 30
Running Refaster - The Picnic Way
Refaster runner - `pom.xml` in Error Prone Support

31. 31
Refaster @ Picnic

32. 32
Advanced Refaster features

33. 33
Multiple
`@BeforeTemplate`s

34. 34
Refaster#anyOf

35. 35
@AlsoNegation

36. 36
Import policies

IMPORT_TOP_LEVEL

IMPORT_CLASS_DIRECTLY

STATIC_IMPORT_ALWAYS

37. 37
Block Template

38. 38
@Placeholder

39. 39
Argument types

40. 40
Workshop Refaster
60+ minutes

Tip: use the slides
PicnicSupermarket/
error-prone-support
branch: workshop
Workshop README

41. 41
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality1
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic

42. 42
Deep dive Error Prone
-Background

-How to write a BugPattern?

-Automatically fixing code

-How to test a BugPattern?

43. 43
Error Prone background
-2012 - Edward Aftandilian

-Code review and unit testing

-Subclass JavaCompiler

-CompilationUnit level
Source: Error Prone paper

44. 44
Rules for an Error Prone check
1.The bug should be easy to understand.

2.The fix should be easy to make.

3.No false positives.

4.The bug should represent a correctness issue.

5.The bug should occur with a small but noticeable frequency.
https://errorprone.info/docs/criteria

45. 45
How does Error Prone work?
Java code Abstract Syntax Tree Tree Node

46. 46
Abstract Syntax Tree

47. 47
Abstract Syntax Tree

48. 48
Creating a BugChecker

49. 49
Automatically fixing code!
Flagging vs. Fixing

50. 50

51. 51
Testing our BugChecker

52. 52
Testing our
BugChecker

53. 53
Refaster vs. Error Prone
Easy: work with
concrete syntax
Complex: AST
manipulation code
Limited
expressiveness
Full AST available
Refactoring only Also flags
without suggestions

54. 54
Workshop part 2 - Error Prone
60 minutes

Prize

Workshop README

55. 55
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality1
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic

56. 56
Roadmap to Enable Error Prone
Level 1:
Disable everything
Level 2:
Selectively enable a
few ERROR checks

Level 3:
Enable all default
ERROR checks

57. 57
Demo: introducing Error Prone in
practice!

58. 58
Roadmap to Enable Error Prone
Level 1:
Disable everything

Level 2:
Selectively turn on a
few ERROR checks

Level 3:
Turn on all default
ERROR checks

59. 59
Agenda
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Agenda
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduce Error Prone and Refaster (10 min)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)5
Error Prone Support (5 min)5
Picnic and its code quality
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!6
Picnic and its code quality (10 min)
Introduction Error Prone and Refaster (10)2
Workshop 1 - Refaster (65 min) 3
Workshop 2 - Error Prone (65 min)4
Using Error Prone in practice! (15 min)6
Error Prone Support (5 min)5
Picnic and its code quality1
Introduction of Error Prone and Refaster2
Workshop 1 - Initial setup3
Workshop 2 - Refaster4
Workshop 3 - Error Prone5
Using Error Prone in practice!
Standardization and repetitive discussions
Introduce Error Prone and Refaster2
Refaster - Workshop part 14
Error Prone - Workshop part 25
Error Prone Support3
Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)5Using Error Prone in practice! (15 min)5Using Error Prone in practice!6Using Error Prone in practice! (15 min)7Error Prone @ Picnic

60. 60
Error Prone @ Picnic
Common configuration
./patch.sh
Continuous Integration

61. 61
Applying Error Prone Support @ Picnic
Introducing:
-all Refaster rules

-all Error Prone checks
https://error-prone.picnic.tech

62. 62
Applying Error Prone Support @ Picnic
60+ PRs spread over 40+ Java repositories

33.665 insertions (+) 31.281 deletions (-)

63. 63

64. 64

65. 65
Current state of Error Prone Support
People contributing ideas (from reviews)

50+ contributors

Stickers

Adoption

External adoption

66. 66
Picnic x Moderne
+

67. 67
In summary
Two perspectives:
-Happy developers!

-Platform team or configuration
maintainers.

68. 68

69. 69
Unsure about next steps?
Feel free to reach out!
error-prone.picnic.tech
Jan Kothe
Contact details for vacancies
My contact details:
[email protected]
github.com/rickie
rick_ossies
github.com/rickie/error-prone-demo Demo + setup