[ruby/irb] Centralize coloring control (https://github.com/ruby/irb/pull/374)

* Use colorable: argument as the only coloring control

* Centalize color controling logic at Color.colorable?

There are 2 requirements for coloring output:

1. It's supported on the platform
2. The user wants it: `IRB.conf[:USE_COLORIZE] == true`

Right now we check 1 and 2 separately whenever we colorize things.
But it's error-prone because while 1 is the default of `colorable`
parameter, 2 always need to manually checked. When 2 is overlooked, it
causes issues like https://github.com/ruby/irb/pull/362

And there's 0 case where we may want to colorize even when the user
disables it. So I think we should merge 2 into `Color.colorable?` so it
can be automatically picked up.

* Add tests for all inspect modes

* Simplify inspectors' coloring logic

* Replace use_colorize? with Color.colorable?

* Remove Context#use_colorize cause it's redundant

https://github.com/ruby/irb/commit/1c53023ac4

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/irb/cmd/show_source.rb b/lib/irb/cmd/show_source.rb
index 7e790c3c93..f8a17822df 100644
--- a/lib/irb/cmd/show_source.rb
+++ b/lib/irb/cmd/show_source.rb
@@ -30,7 +30,7 @@ module IRB
         puts
         puts "#{bold("From")}: #{source.file}:#{source.first_line}"
         puts
-        code = IRB::Color.colorize_code(File.read(source.file), colorable: colorable)
+        code = IRB::Color.colorize_code(File.read(source.file))
         puts code.lines[(source.first_line - 1)...source.last_line].join
         puts
       end
@@ -78,7 +78,7 @@ module IRB
       end
 
       def bold(str)
-        Color.colorize(str, [:BOLD], colorable: colorable)
+        Color.colorize(str, [:BOLD])
       end
 
       Source = Struct.new(