Remove the need for an external dependency for ANSI color

CHANGELOG.md

@@ -56,6 +56,7 @@ appear at the top.
     * Backend implementations now only need to implement `execute_command`, `upload!` and `download!`
     * Removed `Printer` from backend hierarchy for `Local` and `Netssh` backends (they now just extend `Abstract`)
     * Removed unused `Net::SSH:LogLevelShim`
+  * Removed dependency on the `colorize` gem. SSHKit now implements its own ANSI color logic, with no external dependencies. Note that SSHKit now only supports the `:bold` or plain modes. Other modes will be gracefully ignored. [#263](https://github.com/capistrano/sshkit/issues/263)
 
 ## 1.7.1
 

lib/sshkit/color.rb

@@ -1,16 +1,56 @@
-require 'colorize'
-
 module SSHKit
+  # Very basic support for ANSI color, so that we don't have to rely on
+  # any external dependencies. This class handles colorizing strings, and
+  # automatically disabling color if the underlying output is not a tty.
+  #
   class Color
+    COLOR_CODES = {
+      :black   => 30,
+      :red     => 31,
+      :green   => 32,
+      :yellow  => 33,
+      :blue    => 34,
+      :magenta => 35,
+      :cyan    => 36,
+      :white   => 37,
+      :light_black   => 90,
+      :light_red     => 91,
+      :light_green   => 92,
+      :light_yellow  => 93,
+      :light_blue    => 94,
+      :light_magenta => 95,
+      :light_cyan    => 96,
+      :light_white   => 97
+    }.freeze
+
     def initialize(output, env=ENV)
       @output, @env = output, env
     end
 
+    # Converts the given obj to string and surrounds in the appropriate ANSI
+    # color escape sequence, based on the specified color and mode. The color
+    # must be a symbol (see COLOR_CODES for a complete list).
+    #
+    # If the underlying output does not support ANSI color (see `colorize?),
+    # the string will be not be colorized. Likewise if the specified color
+    # symbol is unrecognized, the string will not be colorized.
+    #
+    # Note that the only mode currently support is :bold. All other values
+    # will be silently ignored (i.e. treated the same as mode=nil).
+    #
     def colorize(obj, color, mode=nil)
       string = obj.to_s
-      colorize? ? string.colorize(color: color, mode: mode) : string
+      return string unless colorize?
+      return string unless COLOR_CODES.key?(color)
+
+      result = mode == :bold ? "\e[1;" : "\e[0;"
+      result << COLOR_CODES.fetch(color).to_s
+      result << ";49m#{string}\e[0m"
     end
 
+    # Returns `true` if the underlying output is a tty, or if the SSHKIT_COLOR
+    # environment variable is set.
+    #
     def colorize?
       @env['SSHKIT_COLOR'] || (@output.respond_to?(:tty?) && @output.tty?)
     end

sshkit.gemspec

@@ -19,7 +19,6 @@ Gem::Specification.new do |gem|
 
   gem.add_runtime_dependency('net-ssh',  '>= 2.8.0')
   gem.add_runtime_dependency('net-scp',  '>= 1.1.2')
-  gem.add_runtime_dependency('colorize', '>= 0.7.0')
 
   gem.add_development_dependency('minitest', ['>= 2.11.3', '< 2.12.0'])
   gem.add_development_dependency('rake')

test/unit/test_color.rb

@@ -26,5 +26,55 @@ def test_does_not_colorize_when_tty_method_not_defined_and_SSHKIT_COLOR_not_pres
       color = SSHKit::Color.new(stub(), {})
       assert_equal 'hi', color.colorize('hi', :red)
     end
+
+    def test_colorize_colors
+      color = SSHKit::Color.new(stub(tty?: true), {})
+      assert_equal "\e[0;30;49mhi\e[0m", color.colorize('hi', :black)
+      assert_equal "\e[0;31;49mhi\e[0m", color.colorize('hi', :red)
+      assert_equal "\e[0;32;49mhi\e[0m", color.colorize('hi', :green)
+      assert_equal "\e[0;33;49mhi\e[0m", color.colorize('hi', :yellow)
+      assert_equal "\e[0;34;49mhi\e[0m", color.colorize('hi', :blue)
+      assert_equal "\e[0;35;49mhi\e[0m", color.colorize('hi', :magenta)
+      assert_equal "\e[0;36;49mhi\e[0m", color.colorize('hi', :cyan)
+      assert_equal "\e[0;37;49mhi\e[0m", color.colorize('hi', :white)
+      assert_equal "\e[0;90;49mhi\e[0m", color.colorize('hi', :light_black)
+      assert_equal "\e[0;91;49mhi\e[0m", color.colorize('hi', :light_red)
+      assert_equal "\e[0;92;49mhi\e[0m", color.colorize('hi', :light_green)
+      assert_equal "\e[0;93;49mhi\e[0m", color.colorize('hi', :light_yellow)
+      assert_equal "\e[0;94;49mhi\e[0m", color.colorize('hi', :light_blue)
+      assert_equal "\e[0;95;49mhi\e[0m", color.colorize('hi', :light_magenta)
+      assert_equal "\e[0;96;49mhi\e[0m", color.colorize('hi', :light_cyan)
+      assert_equal "\e[0;97;49mhi\e[0m", color.colorize('hi', :light_white)
+    end
+
+    def test_colorize_bold_colors
+      color = SSHKit::Color.new(stub(tty?: true), {})
+      assert_equal "\e[1;30;49mhi\e[0m", color.colorize('hi', :black, :bold)
+      assert_equal "\e[1;31;49mhi\e[0m", color.colorize('hi', :red, :bold)
+      assert_equal "\e[1;32;49mhi\e[0m", color.colorize('hi', :green, :bold)
+      assert_equal "\e[1;33;49mhi\e[0m", color.colorize('hi', :yellow, :bold)
+      assert_equal "\e[1;34;49mhi\e[0m", color.colorize('hi', :blue, :bold)
+      assert_equal "\e[1;35;49mhi\e[0m", color.colorize('hi', :magenta, :bold)
+      assert_equal "\e[1;36;49mhi\e[0m", color.colorize('hi', :cyan, :bold)
+      assert_equal "\e[1;37;49mhi\e[0m", color.colorize('hi', :white, :bold)
+      assert_equal "\e[1;90;49mhi\e[0m", color.colorize('hi', :light_black, :bold)
+      assert_equal "\e[1;91;49mhi\e[0m", color.colorize('hi', :light_red, :bold)
+      assert_equal "\e[1;92;49mhi\e[0m", color.colorize('hi', :light_green, :bold)
+      assert_equal "\e[1;93;49mhi\e[0m", color.colorize('hi', :light_yellow, :bold)
+      assert_equal "\e[1;94;49mhi\e[0m", color.colorize('hi', :light_blue, :bold)
+      assert_equal "\e[1;95;49mhi\e[0m", color.colorize('hi', :light_magenta, :bold)
+      assert_equal "\e[1;96;49mhi\e[0m", color.colorize('hi', :light_cyan, :bold)
+      assert_equal "\e[1;97;49mhi\e[0m", color.colorize('hi', :light_white, :bold)
+    end
+
+    def test_ignores_unrecognized_color
+      color = SSHKit::Color.new(stub(tty?: true), {})
+      assert_equal 'hi', color.colorize('hi', :tangerine)
+    end
+
+    def test_ignores_unrecognized_mode
+      color = SSHKit::Color.new(stub(tty?: true), {})
+      assert_equal "\e[0;31;49mhi\e[0m", color.colorize('hi', :red, :underline)
+    end
   end
 end