Raise an activation error if a rubygem is already activated that conflicts with the Gemfile

2 files changed, 35 insertions, 0 deletions

diff --git a/lib/bundler/runtime.rb b/lib/bundler/runtime.rb
index 5471aae02b..f4a24b48d5 100644
--- a/lib/bundler/runtime.rb
+++ b/lib/bundler/runtime.rb
@@ -23,6 +23,14 @@ module Bundler
           raise GemNotFound, "#{spec.full_name} is missing. Run `bundle` to get it."
         end
 
+        if activated_spec = Gem.loaded_specs[spec.name] and activated_spec.version != spec.version
+          e = Gem::LoadError.new "You have already activated #{activated_spec.name} #{activated_spec.version}, " \
+                                 "but your Gemfile requires #{spec.name} #{spec.version}. Consider using bundle exec."
+          e.name = spec.name
+          e.version_requirement = Gem::Requirement.new(spec.version.to_s)
+          raise e
+        end
+
         Gem.loaded_specs[spec.name] = spec
         spec.load_paths.each do |path|
           $LOAD_PATH.unshift(path) unless $LOAD_PATH.include?(path)
diff --git a/spec/runtime/setup_spec.rb b/spec/runtime/setup_spec.rb
index e3c133ff75..8623bc2e39 100644
--- a/spec/runtime/setup_spec.rb
+++ b/spec/runtime/setup_spec.rb
@@ -166,6 +166,33 @@ describe "Bundler.setup" do
     end
   end
 
+  describe "preactivated gems" do
+    it "raises an exception if a pre activated gem conflicts with the bundle" do
+      system_gems "thin-1.0", "rack-1.0.0"
+      build_gem "thin", "1.1", :to_system => true do |s|
+        s.add_dependency "rack"
+      end
+
+      gemfile <<-G
+        gem "thin", "1.0"
+      G
+
+      ruby <<-R
+        require 'rubygems'
+        gem "thin"
+        require 'bundler'
+        begin
+          Bundler.setup
+          puts "FAIL"
+        rescue Gem::LoadError => e
+          puts e.message
+        end
+      R
+
+      out.should == "You have already activated thin 1.1, but your Gemfile requires thin 1.0. Consider using bundle exec."
+    end
+  end
+
   # Rubygems returns loaded_from as a string
   it "has loaded_from as a string on all specs" do
     build_git "foo"