Introduce Grape::Validations::CoerceOptions value object

[ericproulx]

Summary

ValidationsSpec#coerce_options returned an ad-hoc { type:, method:, message: } Hash that flowed (deep-frozen) into CoerceValidator as its options argument and was poked at by ParamsScope#check_coerce_with / #validate_coerce.

Unlike most validator options (which are a genuine union — bare value, { value:, message: } envelope, or structured Hash, depending on what the user wrote), this one is never written by the user. It's assembled internally from the parsed type: / coerce_with: / coerce_message declaration, so it has a fixed shape and no public contract to preserve — the cleanest possible Data.define candidate.

Replace it with Grape::Validations::CoerceOptions:

CoerceOptions = Data.define(:type, :coerce_method, :message) do
  def initialize(type: nil, coerce_method: nil, message: nil)
    super
  end
end

The member is coerce_method, not method — defining :method would shadow Object#method (Lint/DataDefineOverride), and coerce_method already matches ValidationsSpec's existing accessor name.

Changes

• ValidationsSpec#coerce_options builds the value object.
• ParamsScope#check_coerce_with / #validate_coerce read .type / .coerce_method instead of [:type] / [:method].
• CoerceValidator reads @options.type / @options.coerce_method. Base#message resolves a custom message by probing a Hash-like key?, which a Data doesn't answer, so CoerceValidator#initialize restores @exception_message from @options.message — preserving type: { value: Integer, message: 'bad' } behaviour (covered by existing specs).

Why it's safe

• Grape::Util::DeepFreeze returns the Data via its else branch unchanged; Base.new already freezes the whole validator instance, and Data is structurally immutable.
• No user-facing contract change: users never construct or read this Hash; no spec hand-builds a CoerceValidator with it (the validator specs go through the full Grape::API DSL).
• The remountable-API return unless coerce_options.type guard in validate_coerce is preserved (a base instance with no resolved type still skips).

Test plan

• bundle exec rspec — 2307 examples, 0 failures (incl. coerce_validator_spec 97/0, custom-message path)
• RuboCop clean (incl. Lint/DataDefineOverride)
• CI green across Gemfile variants

🤖 Generated with Claude Code

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