Introduce RuboCop Performance #316
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tagliala
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Aug 1, 2025
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Disable `CollectionLiteralInLoop` cop in specs Automatically fix safe offenses: - Performance/BindCall - Performance/DoubleStartEndWith - Performance/StringReplacement ``` rubocop --only Performance/BindCall,Performance/DoubleStartEndWith,Performance/StringReplacement -a ```
`String#include?` is considerably more efficient than `String#match?`. However, for uniformity and future-proofing with minimal modifications, it is preferable to permit that comparison in capabilities detection.
Implementing a comprehensive fix for this issue may be regarded as a
disruptive change due to its impact on the API.
Specifically, a partial solution will introduce
`Lint/UnusedMethodArgument` violations, which can be disregarded.
However, benchmarking indicates that removing the `&block` argument
from the method signature will result a performance improvement:
```
ruby 3.4.5 (2025-07-16 revision 20cda200d3) +PRISM [arm64-darwin24]
Comparison (IPS):
yield (no args): 10747202.2 i/s
yield (&block arg): 9308969.9 i/s - 1.15x (± 0.00) slower
block.call: 8607805.1 i/s - 1.25x (± 0.00) slower
```
Ref:
- https://github.com/fastruby/fast-ruby?tab=readme-ov-file#proccall-and-block-arguments-vs-yield-code
``` rubocop --only Performance/MapCompact -A ``` These changes are safe because both `providers` and `capabilities` are a `Hash`, so they both include `Enumerable` and respond to `filter_map` Ref: - https://ruby-doc.org/core-3.1.0/Enumerable.html#method-i-filter_map
While `String#dup` is as fast as `+''` in Ruby >= 3.3, this is not the
case for `String.new`, so this cop has been applied only in production
code.
RuboCop considers this change unsafe because `+''` returns an UTF-8
string, while `String.new` returns an ASCII string.
In this context, this should not be a breaking change.
```
rubocop --only Performance/UnfreezeString -A
```
A manual fix has been applied in ActsAs concern to use empty string
literal for ActiveRecord `content` assignment instead of `String.new` or
`+''`. Passing `''` directly to ActiveRecord is sufficient since the
string isn't mutated.
Bench:
```
ruby 3.4.5 (2025-07-16 revision 20cda200d3) +PRISM [arm64-darwin24]
Comparison (IPS):
+'': 15938643.5 i/s
String.new: 11016752.0 i/s - 1.45x (± 0.00) slower
```
Ref:
- https://docs.rubocop.org/rubocop-performance/cops_performance.html#performanceunfreezestring
- https://github.com/fastruby/fast-ruby?tab=readme-ov-file#stringdup-vs-string-code
There is no auto-correction for this offense, so it has been fixed manually Ref: https://github.com/fastruby/fast-ruby#normal-way-to-apply-method-vs-method-code
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #316 +/- ##
=======================================
Coverage 87.75% 87.75%
=======================================
Files 88 88
Lines 3480 3480
Branches 724 724
=======================================
Hits 3054 3054
Misses 426 426 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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What this does
Hello, thanks for your work on this library
This is my first contribution here. I think that adding RuboCop Performance plugin this can benefit on the long term
Each offense has been fixed in an individual commit, with explanation and benchmarks, where possible.
Some cops have been temporarily disabled because they can break API
Type of change
Scope check
Quality check
overcommit --installand all hooks passI updated documentation if neededmodels.json,aliases.json)API changes
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