From a959fae036735dabfc856abcf58f522985e19605 Mon Sep 17 00:00:00 2001
From: David Waite <david@alkaline-solutions.com>
Date: Tue, 2 Jun 2009 20:07:31 -0600
Subject: [PATCH] Add GEM_COMMAND environment variable, to allow for overriding the default choice for gem executable name.

---
 railties/lib/rails/gem_dependency.rb |   16 +++++++++-------
 railties/test/gem_dependency_test.rb |   10 ++++++++++
 railties/test/test_script.rb         |    5 +++++
 3 files changed, 24 insertions(+), 7 deletions(-)
 create mode 100644 railties/test/test_script.rb

diff --git a/railties/lib/rails/gem_dependency.rb b/railties/lib/rails/gem_dependency.rb
index ee3d0d8..c11cf3e 100644
--- a/railties/lib/rails/gem_dependency.rb
+++ b/railties/lib/rails/gem_dependency.rb
@@ -256,13 +256,15 @@ module Rails
     private
 
       def gem_command
-        case RUBY_PLATFORM
-          when /win32/
-            'gem.bat'
-          when /java/
-            'jruby -S gem'
-          else
-            'gem'
+        @gem_command ||= begin
+          ENV['GEM_COMMAND'] || case RUBY_PLATFORM
+            when /win32/
+              'gem.bat'
+            when /java/
+              'jruby -S gem'
+            else
+              'gem'
+          end
         end
       end
 
diff --git a/railties/test/gem_dependency_test.rb b/railties/test/gem_dependency_test.rb
index 3853eb5..7f693ce 100644
--- a/railties/test/gem_dependency_test.rb
+++ b/railties/test/gem_dependency_test.rb
@@ -1,4 +1,5 @@
 require 'plugin_test_helper'
+require 'tmpdir'
 
 class Rails::GemDependency
   public :install_command, :unpack_command
@@ -186,4 +187,13 @@ class GemDependencyTest < Test::Unit::TestCase
     assert_equal false, Rails::GemDependency.new("dummy-gem-j").built?
   end
 
+  def test_gem_environment_override
+    ENV['GEM_COMMAND'] = "#{ENV['_']} ./test_script.rb"
+    @gem              = Rails::GemDependency.new "xhpricotx"
+    filename = Dir.tmpdir + '/test-script'
+    puts filename
+    File.delete(filename) rescue nil
+    @gem.install
+    assert_equal true, File.exists?(filename)
+  end
 end
diff --git a/railties/test/test_script.rb b/railties/test/test_script.rb
new file mode 100644
index 0000000..fe5a664
--- /dev/null
+++ b/railties/test/test_script.rb
@@ -0,0 +1,5 @@
+#!/usr/bin/env ruby
+require 'tmpdir'
+
+filename = Dir.tmpdir + '/test-script'
+File.open(filename, 'w') { |f| f.write('successful') }
-- 
1.6.3.1