Use match? in FactoryBot#aliases_for to save allocations

[Aqualon]

FactoryBot relies on ruby >= 2.5, so we can use Regexp#match? that does not allocate MatchData

Allocations measured with heap-profiler gem in an internal test suite with 7497 examples and 149470 calls to aliases_for:

allocated memory by file

59.79 MB  factory_bot-6.1.0/lib/factory_bot/aliases.rb
38.27 MB  factory_bot-6.1.0/lib/factory_bot/aliases.rb

allocated objects by file

896880  factory_bot-6.1.0/lib/factory_bot/aliases.rb
597940  factory_bot-6.1.0/lib/factory_bot/aliases.rb

The remaining allocations are mainly caused by

factory_bot/lib/factory_bot/aliases.rb

Line 14 in 9e58a34

attribute.to_s.sub(pattern, replace).to_sym

In the test suite I used, I noticed that attribute values are repeated quite often. For the 149470 calls I just got 16 unique attribute values. So a simple caching mechanism prevents most of the allocations:

  @aliases_for_cache = {}

  def self.aliases_for(attribute)
    @aliases_for_cache[attribute] ||=
      aliases.map { |(pattern, replace)|
        if pattern.match?(attribute)
          attribute.to_s.sub(pattern, replace).to_sym
        end
      }.compact << attribute
  end

In another test suite I got 56 unique attribute values for 228979 calls to aliases_for. I don't know if this is representative for other users of FactoryBot, but I could prepare a second PR with the cache idea.

[entcheva]

Why are we removing to_s? Do we know why we were calling it here in the first place?

[Aqualon]

I'm not sure about this part either, I tried it with symbol and string attributes and it both worked. But maybe there could be scenarios where attribute is another ruby object, that implements to_s? Don't know enough details about factory_bot there.

[composerinteralia]

Tracing back through the callers it seems like attribute here is always a symbol, and Regexp#match seems to work fine with a symbol (maybe that wasn't always true?), so change seems good to me.

[MatheusRich]

How can we move this forward? Just adding .to_s back would make this ready to go?