remove colors if printing errors to stderr without a tty available

2 files changed, 4 insertions, 2 deletions

diff --git a/lib/bundler/ui/shell.rb b/lib/bundler/ui/shell.rb
index 81743ede40..5d4fd76acb 100644
--- a/lib/bundler/ui/shell.rb
+++ b/lib/bundler/ui/shell.rb
@@ -9,7 +9,7 @@ module Bundler
       attr_writer :shell
 
       def initialize(options = {})
-        if options["no-color"] || !STDOUT.tty?
+        if options["no-color"] || !$stdout.tty?
           Thor::Base.shell = Thor::Shell::Basic
         end
         @shell = Thor::Base.shell.new
@@ -108,6 +108,8 @@ module Bundler
         newline = message.to_s !~ /( |\t)\Z/ unless newline
         message = word_wrap(message) if newline.is_a?(Hash) && newline[:wrap]
 
+        color = nil if color && !$stderr.tty?
+
         buffer = @shell.send(:prepare_message, message, *color)
         buffer << "\n" if newline && !message.to_s.end_with?("\n")
 
diff --git a/spec/bundler/ui/shell_spec.rb b/spec/bundler/ui/shell_spec.rb
index 2db2d28641..050fb9c1fb 100644
--- a/spec/bundler/ui/shell_spec.rb
+++ b/spec/bundler/ui/shell_spec.rb
@@ -42,7 +42,7 @@ RSpec.describe Bundler::UI::Shell do
     context "when stderr flag is enabled" do
       before { bundle "config error_on_stderr true" }
       it "prints to stderr" do
-        expect { subject.error("error!!!") }.to output("\e[31merror!!!\e[0m\n").to_stderr
+        expect { subject.error("error!!!") }.to output("error!!!\n").to_stderr
       end
     end
   end