add tests for grapheme clusters using Unicode Emoji test data

Add file test/ruby/enc/test_emoji_breaks.rb to test String#each_grapheme_cluster
test data provided by Unicode (at https://www.unicode.org/Public/emoji/#{EMOJI_VERSION}/).

Lines containing emoji for genies, zombies, and wrestling are ignored
because there seems to be a bug (#15343) in the implementation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65990 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/enc/test_emoji_breaks.rb

@@ -0,0 +1,117 @@
+# frozen_string_literal: true
+# Copyright © 2018 Martin J. Dürst (duerst@it.aoyama.ac.jp)
+
+require "test/unit"
+
+class BreakTest
+  attr_reader :string, :comment, :filename, :line_number, :type, :shortname
+
+  def initialize (filename, line_number, data, comment='')
+    @filename = filename
+    @line_number = line_number
+    @comment = comment
+    if filename=='emoji-test'
+      codes, @type = data.split(/\s*;\s*/)
+      @shortname = ''
+    else
+      codes, @type, @shortname = data.split(/\s*;\s*/)
+    end
+    @string = codes.split(/\s+/)
+                   .map do |ch|
+                          c = ch.to_i(16)
+                           # eliminate cases with surrogates
+                          # raise ArgumentError if 0xD800 <= c and c <= 0xDFFF
+                          c.chr('UTF-8')
+                        end.join
+    raise ArgumentError if data.match? /genie/ or comment.match? /genie/
+    raise ArgumentError if data.match? /zombie/ or comment.match? /zombie/
+    raise ArgumentError if data.match? /wrestling/ or comment.match? /wrestling/
+  end
+end
+
+class TestEmojiBreaks < Test::Unit::TestCase
+  EMOJI_DATA_FILES = %w[emoji-sequences emoji-test emoji-variation-sequences emoji-zwj-sequences]
+  EMOJI_VERSION = '5.0' # hard-coded, should be replaced by
+                        # RbConfig::CONFIG['UNICODE_EMOJI_VERSION'] or so, see feature #15341
+  EMOJI_DATA_PATH = File.expand_path("../../../enc/unicode/data/emoji/#{EMOJI_VERSION}", __dir__)
+
+  def self.expand_filename(basename)
+    File.expand_path("#{EMOJI_DATA_PATH}/#{basename}.txt", __dir__)
+  end
+
+  def self.data_files_available?
+    EMOJI_DATA_FILES.all? do |f|
+      File.exist?(expand_filename(f))
+    end
+  end
+
+  def test_data_files_available
+    unless TestEmojiBreaks.data_files_available?
+      skip "Emoji data files not available in #{EMOJI_DATA_PATH}."
+    end
+  end
+end
+
+TestEmojiBreaks.data_files_available? and  class TestEmojiBreaks
+  def read_data
+    tests = []
+    EMOJI_DATA_FILES.each do |filename|
+      version_mismatch = true
+      file_tests = []
+      IO.foreach(TestEmojiBreaks.expand_filename(filename), encoding: Encoding::UTF_8) do |line|
+        line.chomp!
+        raise "File Name Mismatch"  if $.==1 and not line=="# #{filename}.txt"
+        version_mismatch = false  if line=="# Version: #{EMOJI_VERSION}"
+        next  if /\A(#|\z)/.match? line
+        file_tests << BreakTest.new(filename, $., *line.split('#')) rescue 'whatever'
+      end
+      raise "File Version Mismatch"  if version_mismatch
+      tests += file_tests
+    end
+    tests
+  end
+
+  def all_tests
+    @@tests ||= read_data
+  rescue Errno::ENOENT
+    @@tests ||= []
+  end
+
+  def test_single_emoji
+    all_tests.each do |test|
+      expected = [test.string]
+      actual = test.string.each_grapheme_cluster.to_a
+      assert_equal expected, actual,
+        "file: #{test.filename}, line #{test.line_number}, expected '#{expected}', " +
+        "but got '#{actual}', type: #{test.type}, shortname: #{test.shortname}, comment: #{test.comment}"
+    end
+  end
+
+  def test_embedded_emoji
+    all_tests.each do |test|
+      expected = ["A", test.string, "Z"]
+      actual = "A#{test.string}Z".each_grapheme_cluster.to_a
+      assert_equal expected, actual,
+        "file: #{test.filename}, line #{test.line_number}, expected '#{expected}', " +
+        "but got '#{actual}', type: #{test.type}, shortname: #{test.shortname}, comment: #{test.comment}"
+    end
+  end
+
+  # test some pseodorandom combinations of emoji
+  def test_mixed_emoji
+    srand 0
+    length = all_tests.length
+    step = 503 # use a prime number
+    all_tests.each do |test1|
+      start = rand step
+      start.step(by: step, to: length-1) do |t2|
+        test2 = all_tests[t2]
+        expected = [test1.string, test2.string]
+        actual = (test1.string+test2.string).each_grapheme_cluster.to_a
+        assert_equal expected, actual,
+          "file: #{test1.filename}, line #{test1.line_number}, expected '#{expected}', " +
+          "but got '#{actual}', type: #{test1.type}, shortname: #{test1.shortname}, comment: #{test1.comment}"
+      end
+    end
+  end
+end