Add undef: :replace for CSV.open (#129)

This PR adds `undef: :replace` option for `CSV.open`. `File.open` has `undef: :replace` option, but `CSV.open` does not. It would be convenient if `CSV.open` could have a shortcut by having `undef: :replace` option.

Author: koic

lib/csv.rb

@@ -960,6 +960,11 @@ def generate_line(row, **options)
  # open( filename, mode = "rb", **options )
  # open( filename, **options )
  #
+ # possible options elements:
+ # hash form:
+ # :undef => :replace # replace undefined conversion
+ # :replace => string # replacement string ("?" or "\uFFFD" if not specified)
+ #
  # This method opens an IO object, and wraps that with CSV. This is intended
  # as the primary interface for writing a CSV file.
  #
@@ -1021,6 +1026,8 @@ def open(filename, mode="r", **options)
  # wrap a File opened with the remaining +args+ with no newline
  # decorator
  file_opts = {universal_newline: false}.merge(options)
+ options.delete(:undef)
+ options.delete(:replace)
 
  begin
  f = File.open(filename, mode, **file_opts)

test/csv/interface/test_read.rb

@@ -125,6 +125,28 @@ def test_open_encoding_utf_8_with_bom
  end
  end
 
+ def test_open_with_undef_replace
+ # U+00B7 Middle Dot
+ CSV.open(@input.path, "w", encoding: Encoding::CP932, undef: :replace) do |rows|
+ rows << ["\u00B7"]
+ end
+ CSV.open(@input.path, encoding: Encoding::CP932) do |csv|
+ assert_equal([["?"]],
+ csv.to_a)
+ end
+ end
+
+ def test_open_with_undef_replace_and_replace_string
+ # U+00B7 Middle Dot
+ CSV.open(@input.path, "w", encoding: Encoding::CP932, undef: :replace, replace: "X") do |rows|
+ rows << ["\u00B7"]
+ end
+ CSV.open(@input.path, encoding: Encoding::CP932) do |csv|
+ assert_equal([["X"]],
+ csv.to_a)
+ end
+ end
+
  def test_parse
  assert_equal(@rows,
  CSV.parse(@data, col_sep: "\t", row_sep: "\r\n"))