Pattern: Missing use of Hash#transform_keys
Issue: -
This rule looks for uses of _.each_with_object({}) {...},
_.map {...}.to_h, and Hash[_.map {...}] that are actually just
transforming the keys of a hash, and tries to use a simpler & faster
call to transform_keys instead.
This can produce false positives if we are transforming an enumerable
of key-value-like pairs that isn't actually a hash, e.g.:
[[k1, v1], [k2, v2], ...]
# bad
{a: 1, b: 2}.each_with_object({}) { |(k, v), h| h[foo(k)] = v }
{a: 1, b: 2}.map { |k, v| [k.to_s, v] }
# good
{a: 1, b: 2}.transform_keys { |k| foo(k) }
{a: 1, b: 2}.transform_keys { |k| k.to_s }