Fix color command

lib/youplot/backends/unicode_plot_backend.rb

@@ -152,17 +152,23 @@ module YouPlot
       end
 
       def colors(color_names = false)
+        # FIXME
+        s = String.new
         UnicodePlot::StyledPrinter::TEXT_COLORS.each do |k, v|
-          print v
-          print k
+          s << v
+          s << k.to_s
           unless color_names
-            print "\t"
-            print '  ●'
+            s << "\t"
+            s << '  ●'
           end
-          print "\033[0m"
-          print "\t"
+          s << "\033[0m"
+          s << "\t"
         end
-        puts
+        s << "\n"
+        def s.render(obj)
+          obj.print(self)
+        end
+        s
       end
 
       def check_series_size(data, fmt)

lib/youplot/command.rb

@@ -28,14 +28,14 @@ module YouPlot
       @options ||= parser.options
       @params  ||= parser.params
 
-      if command == :colors
-        @backend.colors(parser.color_names)
-        exit
-      end
-
-      # Sometimes the input file does not end with a newline code.
-      while (input = Kernel.gets(nil))
-        main(input)
+      if %i[colors color colours colour].include? @command
+        plot = create_plot
+        output_plot(plot)
+      else
+        # Sometimes the input file does not end with a newline code.
+        while (input = Kernel.gets(nil))
+          main(input)
+        end
       end
     end
 
@@ -75,6 +75,8 @@ module YouPlot
         @backend.density(data, params, options[:fmt])
       when :box, :boxplot
         @backend.boxplot(data, params)
+      when :colors, :color, :colours, :colour
+        @backend.colors(options[:color_names])
       else
         raise "unrecognized plot_type: #{command}"
       end

lib/youplot/command/parser.rb

@@ -123,7 +123,7 @@ module YouPlot
                   scatter    s             draw a scatter plot
                   density    d             draw a density plot
                   boxplot    box           draw a horizontal boxplot
-                  colors                   show the list of available colors
+                  colors     color         show the list of available colors
 
                   count      c             draw a baplot based on the number of 
                                            occurrences (slow)
@@ -252,7 +252,7 @@ module YouPlot
               params.xlim = v.take(2)
             end
 
-          when :colors
+          when :colors, :color, :colours, :colour
             parser.on_head('-n', '--names', 'show color names only', TrueClass) do |v|
               @options[:color_names] = v
             end

test/youplot/command_test.rb

@@ -106,7 +106,7 @@ class YouPlotCommandTest < Test::Unit::TestCase
 
   test :plot_output_stdout do
     YouPlot::Command.new(['bar', '-o', '-H', '-d,', '-t', 'IRIS-BARPLOT']).run
-    assert_equal "", @stderr_file.read
+    assert_equal '', @stderr_file.read
   end
 
   test :data_output_stdout do
@@ -114,4 +114,18 @@ class YouPlotCommandTest < Test::Unit::TestCase
     assert_equal fixture('iris-barplot.txt'), @stderr_file.read
     assert_equal File.read(File.expand_path('../fixtures/iris.csv', __dir__)), @stdout_file.read
   end
+
+  %i[colors color colours colour].each do |cmd_name|
+    test cmd_name do
+      YouPlot::Command.new([cmd_name.to_s]).run
+      assert_equal fixture('colors.txt'), @stderr_file.read
+      assert_equal '', @stdout_file.read
+    end
+  end
+
+  test :colors_output_stdout do
+    YouPlot::Command.new(['colors', '-o']).run
+    assert_equal '', @stderr_file.read
+    assert_equal fixture('colors.txt'), @stdout_file.read
+  end
 end