Chess Game: Rename nick_name method to nickname for consistency (#1769)

Author: lemonade-37

exercises/concept/chess-game/.meta/exemplar.rb

@@ -6,14 +6,14 @@ def self.valid_square?(rank, file)
     RANKS.include?(rank) && FILES.include?(file)
   end
 
-  def self.nick_name(first_name, last_name)
+  def self.nickname(first_name, last_name)
     "#{first_name[...2]}#{last_name[-2..]}".upcase
   end
 
   def self.move_message(first_name, last_name, square)
     rank = square[1].to_i
     file = square[0]
-    name = nick_name(first_name, last_name)
+    name = nickname(first_name, last_name)
     if valid_square?(rank, file)
       "#{name} moved to #{square}"
     else

exercises/concept/chess-game/chess_game.rb

@@ -6,8 +6,8 @@ def self.valid_square?(rank, file)
     raise "Please implement the Chess.valid_square? method"
   end
 
-  def self.nick_name(first_name, last_name)
-    raise "Please implement the Chess.nick_name method"
+  def self.nickname(first_name, last_name)
+    raise "Please implement the Chess.nickname method"
   end
 
   def self.move_message(first_name, last_name, square)

exercises/concept/chess-game/chess_game_test.rb

@@ -30,16 +30,16 @@ def test_false_when_rank_is_less_than_one
     refute Chess.valid_square?(0, 'A')
   end
 
-  def test_correct_player_nick_name
-    assert_equal "JOOE", Chess.nick_name("John", "Doe")
+  def test_correct_player_nickname
+    assert_equal "JOOE", Chess.nickname("John", "Doe")
   end
 
   def test_correct_nickname_for_2_letter_last_name
-    assert_equal "LILI", Chess.nick_name("Lisa", "Li")
+    assert_equal "LILI", Chess.nickname("Lisa", "Li")
   end
 
   def test_correct_nickname_for_2_letter_first_name
-    assert_equal "DJER", Chess.nick_name("Dj", "Walker")
+    assert_equal "DJER", Chess.nickname("Dj", "Walker")
   end
 
   def test_correct_message_for_a_move