Preserve order in dependencies

features/appraisals.feature

@@ -49,6 +49,7 @@ Feature: run a rake task through several appraisals
     When I successfully run `bundle install --local`
     And I successfully run `bundle exec rake appraisal:install --trace`
 
+  @puts @announce
   Scenario: run a specific task with one appraisal
     When I successfully run `bundle exec rake appraisal:1.3.0 version --trace`
     Then the output should contain "Loaded 1.3.0"

lib/appraisal/gemfile.rb

@@ -8,7 +8,7 @@ class Gemfile
 
     def initialize
       @sources = []
-      @dependencies = {}
+      @dependencies = []
     end
 
     def load(path)
@@ -20,7 +20,8 @@ def run(definitions)
     end
 
     def gem(name, *requirements)
-      @dependencies[name] = Dependency.new(name, requirements)
+      @dependencies.reject! { |dependency| dependency.name == name }
+      @dependencies << Dependency.new(name, requirements)
     end
 
     def group(name)
@@ -38,7 +39,7 @@ def to_s
     def dup
       gemfile = Gemfile.new
       @sources.each { |source| gemfile.source source }
-      dependencies.values.each do |dependency|
+      dependencies.each do |dependency|
         gemfile.gem(dependency.name, *dependency.requirements)
       end
       gemfile.gemspec(@gemspec.options) if @gemspec
@@ -56,7 +57,7 @@ def source_entry
     end
 
     def dependencies_entry
-      dependencies.values.map { |dependency| dependency.to_s }.join("\n")
+      dependencies.map { |dependency| dependency.to_s }.join("\n")
     end
 
     def gemspec_entry

spec/appraisal/gemfile_spec.rb

@@ -13,4 +13,12 @@
     gemfile.source "two"
     gemfile.to_s.strip.should == %{source "one"\nsource "two"}
   end
+
+  it "preserves dependency order" do
+    gemfile = Appraisal::Gemfile.new
+    gemfile.gem "one"
+    gemfile.gem "two"
+    gemfile.gem "three"
+    gemfile.to_s.should =~ /one.*two.*three/m
+  end
 end