From a3642508d03011ec92efecd756c7d76612393e45 Mon Sep 17 00:00:00 2001
From: David Waite <david@alkaline-solutions.com>
Date: Wed, 3 Jun 2009 22:22:35 -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 |   18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 7 deletions(-)

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..0e6d382 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 +187,21 @@ class GemDependencyTest < Test::Unit::TestCase
     assert_equal false, Rails::GemDependency.new("dummy-gem-j").built?
   end
 
+  def test_gem_command_override
+    gem = Rails::GemDependency.new('dummy-gem')
+    def gem.gem_command_public
+      gem_command
+    end
+    def gem.gem_command_reset
+      @gem_command = nil
+    end
+
+    fake_gem_command = 'xyzzy'
+
+    assert_not_equal fake_gem_command, gem.gem_command_public
+    gem.gem_command_reset
+
+    ENV['GEM_COMMAND'] = fake_gem_command
+    assert_equal fake_gem_command, gem.gem_command_public
+  end
 end
-- 
1.6.3.1