Display a more human readable list of reserved names

Interpolating an array inside a String will call #inspect on it. Let's
call #join to display a more human-readable error message.

railties/lib/rails/generators/rails/app/app_generator.rb

@@ -356,7 +356,9 @@ def valid_const?
         if app_const =~ /^\d/
           raise Error, "Invalid application name #{app_name}. Please give a name which does not start with numbers."
         elsif RESERVED_NAMES.include?(app_name)
-          raise Error, "Invalid application name #{app_name}. Please give a name which does not match one of the reserved rails words: #{RESERVED_NAMES}"
+          raise Error, "Invalid application name #{app_name}. Please give a " \
+                       "name which does not match one of the reserved rails " \
+                       "words: #{RESERVED_NAMES.join(", ")}"
         elsif Object.const_defined?(app_const_base)
           raise Error, "Invalid application name #{app_name}, constant #{app_const_base} is already in use. Please choose another application name."
         end

railties/lib/rails/generators/rails/plugin/plugin_generator.rb

@@ -364,7 +364,9 @@ def valid_const?
         elsif camelized =~ /^\d/
           raise Error, "Invalid plugin name #{original_name}. Please give a name which does not start with numbers."
         elsif RESERVED_NAMES.include?(name)
-          raise Error, "Invalid plugin name #{original_name}. Please give a name which does not match one of the reserved rails words: #{RESERVED_NAMES}"
+          raise Error, "Invalid plugin name #{original_name}. Please give a " \
+                       "name which does not match one of the reserved rails " \
+                       "words: #{RESERVED_NAMES.join(", ")}"
         elsif Object.const_defined?(camelized)
           raise Error, "Invalid plugin name #{original_name}, constant #{camelized} is already in use. Please choose another plugin name."
         end

railties/test/generators/plugin_generator_test.rb

@@ -38,7 +38,7 @@ def test_invalid_plugin_name_raises_an_error
     assert_equal "Invalid plugin name 43things. Please give a name which does not start with numbers.\n", content
 
     content = capture(:stderr){ run_generator [File.join(destination_root, "plugin")] }
-    assert_equal "Invalid plugin name plugin. Please give a name which does not match one of the reserved rails words: [\"application\", \"destroy\", \"plugin\", \"runner\", \"test\"]\n", content
+    assert_equal "Invalid plugin name plugin. Please give a name which does not match one of the reserved rails words: application, destroy, plugin, runner, test\n", content
 
     content = capture(:stderr){ run_generator [File.join(destination_root, "Digest")] }
     assert_equal "Invalid plugin name Digest, constant Digest is already in use. Please choose another plugin name.\n", content

railties/test/generators/shared_generator_tests.rb

@@ -56,7 +56,7 @@ def test_name_collision_raises_an_error
     reserved_words = %w[application destroy plugin runner test]
     reserved_words.each do |reserved|
       content = capture(:stderr){ run_generator [File.join(destination_root, reserved)] }
-      assert_match(/Invalid \w+ name #{reserved}. Please give a name which does not match one of the reserved rails words: \["application", "destroy", "plugin", "runner", "test"\]\n/, content)
+      assert_match(/Invalid \w+ name #{reserved}. Please give a name which does not match one of the reserved rails words: application, destroy, plugin, runner, test\n/, content)
     end
   end