Module: Spoom::Sorbet::Translate::Validator

Defined in:
lib/spoom/sorbet/translate/validator.rb

Overview

Checks that a translation preserved the lines of every “landmark” (e.g. classes, method defs, and so on) so line numbers in the rewritten output still line up with the original source.

Class Method Summary collapse

Class Method Details

.validate(original, rewritten) ⇒ Object

Compares the landmarks in both sources and returns a result describing what changed:

missing_from_rewritten_output - dropped: an occurrence in the original
                                that is gone from the rewrite
excess_in_rewritten_output    - added: an occurrence in the rewrite with
                                no match in the original
on_wrong_line                 - survived but moved to a different line

: (String original, String rewritten) -> ValidationResult



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# File 'lib/spoom/sorbet/translate/validator.rb', line 25

def validate(original, rewritten)
  original_landmarks = LandmarkFinder.find_landmarks_in(original)
  rewritten_landmarks = LandmarkFinder.find_landmarks_in(rewritten)

  missing = []
  excess = []
  on_wrong_line = []

  (original_landmarks.keys | rewritten_landmarks.keys).each do |landmark_id|
    original_lines = original_landmarks.fetch(landmark_id, [])
    rewritten_lines = rewritten_landmarks.fetch(landmark_id, [])

    dropped = original_lines - rewritten_lines
    added = rewritten_lines - original_lines

    if dropped.any? && added.any?
      # Present in both but on different lines: the landmark moved.
      on_wrong_line << { landmark_id:, expected: dropped, actual: added }
    else
      dropped.each { |line| missing << { landmark_id:, line: } }
      added.each { |line| excess << { landmark_id:, line: } }
    end
  end

  if original.lines.count != rewritten.lines.count
    on_wrong_line << { landmark_id: "EOF", expected: [original.lines.count], actual: [rewritten.lines.count] }
  end

  ValidationResult.new(
    missing_from_rewritten_output: missing,
    excess_in_rewritten_output: excess,
    on_wrong_line: on_wrong_line,
  )
end