[ruby/reline] Use color name instead of code (integer) in dialog color APIs

As pointed out in the
[comment](https://github.com/ruby/reline/pull/413#issuecomment-1168033973),
the code is actually a control sequence and not only for colors.

To make the dialog color APIs safer to use, we should restrict its
usages and extract away the bg/fg concept from the input.

So in this commit, I made these changes:

1. The dialog_*_bg/fg_color APIs only takes and returns color names (symbol):
  - :black
  - :red
  - :green
  - :yellow
  - :blue
  - :magenta
  - :cyan
  - :white
2. Add additional dialog_*_bg/fg_color_sequence APIs to access the raw code.

https://github.com/ruby/reline/commit/b32a977766

2 files changed, 33 insertions, 21 deletions

diff --git a/test/reline/test_config.rb b/test/reline/test_config.rb
index 234eee11f7..eaee2fd580 100644
--- a/test/reline/test_config.rb
+++ b/test/reline/test_config.rb
@@ -411,16 +411,16 @@ class Reline::Config::Test < Reline::TestCase
 
   def test_dialog_configurations
     @config.read_lines(<<~LINES.lines)
-      set dialog-default-bg-color 1
-      set dialog-pointer-bg-color 2
-      set dialog-default-fg-color 3
-      set dialog-pointer-fg-color 4
+      set dialog-default-bg-color white
+      set dialog-pointer-bg-color black
+      set dialog-default-fg-color cyan
+      set dialog-pointer-fg-color magenta
     LINES
 
-    assert_equal 1, @config.dialog_default_bg_color
-    assert_equal 2, @config.dialog_pointer_bg_color
-    assert_equal 3, @config.dialog_default_fg_color
-    assert_equal 4, @config.dialog_pointer_fg_color
+    assert_equal :white, @config.dialog_default_bg_color
+    assert_equal :black, @config.dialog_pointer_bg_color
+    assert_equal :cyan, @config.dialog_default_fg_color
+    assert_equal :magenta, @config.dialog_pointer_fg_color
   end
 end
 
diff --git a/test/reline/test_reline.rb b/test/reline/test_reline.rb
index 0201fb3a75..6717914c64 100644
--- a/test/reline/test_reline.rb
+++ b/test/reline/test_reline.rb
@@ -48,19 +48,31 @@ class Reline::Test < Reline::TestCase
 
   def test_dialog_color_configuration
     # defaults
-    assert_equal(46, Reline.dialog_default_bg_color)
-    assert_equal(37, Reline.dialog_default_fg_color)
-    assert_equal(45, Reline.dialog_pointer_bg_color)
-    assert_equal(37, Reline.dialog_pointer_fg_color)
-
-    Reline.dialog_default_bg_color = 40
-    assert_equal(40, Reline.dialog_default_bg_color)
-    Reline.dialog_default_fg_color = 47
-    assert_equal(47, Reline.dialog_default_fg_color)
-    Reline.dialog_pointer_bg_color = 37
-    assert_equal(37, Reline.dialog_pointer_bg_color)
-    Reline.dialog_pointer_fg_color = 30
-    assert_equal(30, Reline.dialog_pointer_fg_color)
+    assert_equal(:cyan, Reline.dialog_default_bg_color)
+    assert_equal(:white, Reline.dialog_default_fg_color)
+    assert_equal(:magenta, Reline.dialog_pointer_bg_color)
+    assert_equal(:white, Reline.dialog_pointer_fg_color)
+
+    Reline.dialog_default_bg_color = :black
+    assert_equal(:black, Reline.dialog_default_bg_color)
+    assert_equal(40, Reline.dialog_default_bg_color_sequence)
+
+    Reline.dialog_default_fg_color = :white
+    assert_equal(:white, Reline.dialog_default_fg_color)
+    assert_equal(37, Reline.dialog_default_fg_color_sequence)
+
+    Reline.dialog_pointer_bg_color = :white
+    assert_equal(:white, Reline.dialog_pointer_bg_color)
+    assert_equal(47, Reline.dialog_pointer_bg_color_sequence)
+
+    Reline.dialog_pointer_fg_color = :black
+    assert_equal(:black, Reline.dialog_pointer_fg_color)
+    assert_equal(30, Reline.dialog_pointer_fg_color_sequence)
+
+    # test value validation
+    assert_raise(ArgumentError) do
+      Reline.dialog_pointer_fg_color = :foo
+    end
   end
 
   def test_basic_word_break_characters