Fix upgrade/downgrade bug and Add more tests

Author: dfop02

bundler/lib/bundler/plugin.rb

@@ -114,9 +114,6 @@ def gemfile_install(gemfile = nil, &inline)
         return if definition.dependencies.empty?
 
         plugins = definition.dependencies.map(&:name).reject {|p| index.installed? p }
-
-        return if plugins.empty?
-
         installed_specs = Installer.new.install_definition(definition)
 
         save_plugins plugins, installed_specs, builder.inferred_plugins

bundler/lib/bundler/plugin/index.rb

@@ -112,7 +112,7 @@ def command_plugin(command)
       end
 
       # Plugin cannot be installed and updating to install
-      def cannot_install?(name, version)
+      def version_already_installed?(name, version)
         installed?(name) && !updating?(name, version)
       end
 

bundler/lib/bundler/plugin/installer.rb

@@ -100,7 +100,7 @@ def install_from_specs(specs)
         paths = {}
 
         specs.each do |spec|
-          next if cannot_install?(spec.name, spec.version)
+          next if version_already_installed?(spec.name, spec.version)
 
           spec.source.install spec
           paths[spec.name] = spec
@@ -109,14 +109,14 @@ def install_from_specs(specs)
         paths
       end
 
-      # Check if the Plugin is already installed or has a diff version to install
+      # Check if the Plugin version is already installed or has a diff version to install
       #
       # @param [String] name of the plugin gem to search in the source
       # @param [String] version of the gem to install
       #
       # @return [Boolean] true if installed or not updating plugin
-      def cannot_install?(plugin, version)
-        Index.new.cannot_install?(plugin, version)
+      def version_already_installed?(plugin, version)
+        Index.new.version_already_installed?(plugin, version)
       end
     end
   end

bundler/spec/plugins/install_spec.rb

@@ -232,6 +232,78 @@ def exec(command, args)
       plugin_should_be_installed("foo")
     end
 
+    it "upgrade plugins version listed in gemfile" do
+      update_repo2 do
+        build_plugin "foo", "1.4.0"
+        build_plugin "foo", "1.5.0"
+      end
+
+      gemfile <<-G
+        source '#{file_uri_for(gem_repo2)}'
+        plugin 'foo', "1.4.0"
+        gem 'rack', "1.0.0"
+      G
+
+      bundle "install"
+
+      expect(out).to include("Installing foo 1.4.0")
+      expect(out).to include("Installed plugin foo")
+      expect(out).to include("Bundle complete!")
+
+      expect(the_bundle).to include_gems("rack 1.0.0")
+      plugin_should_be_installed("foo")
+
+      gemfile <<-G
+        source '#{file_uri_for(gem_repo2)}'
+        plugin 'foo', "1.5.0"
+        gem 'rack', "1.0.0"
+      G
+
+      bundle "install"
+
+      expect(out).to include("Installing foo 1.5.0")
+      expect(out).to include("Bundle complete!")
+
+      expect(the_bundle).to include_gems("rack 1.0.0")
+      plugin_should_be_installed("foo")
+    end
+
+    it "downgrade plugins version listed in gemfile" do
+      update_repo2 do
+        build_plugin "foo", "1.4.0"
+        build_plugin "foo", "1.5.0"
+      end
+
+      gemfile <<-G
+        source '#{file_uri_for(gem_repo2)}'
+        plugin 'foo', "1.5.0"
+        gem 'rack', "1.0.0"
+      G
+
+      bundle "install"
+
+      expect(out).to include("Installing foo 1.5.0")
+      expect(out).to include("Installed plugin foo")
+      expect(out).to include("Bundle complete!")
+
+      expect(the_bundle).to include_gems("rack 1.0.0")
+      plugin_should_be_installed("foo")
+
+      gemfile <<-G
+        source '#{file_uri_for(gem_repo2)}'
+        plugin 'foo', "1.4.0"
+        gem 'rack', "1.0.0"
+      G
+
+      bundle "install"
+
+      expect(out).to include("Installing foo 1.4.0")
+      expect(out).to include("Bundle complete!")
+
+      expect(the_bundle).to include_gems("rack 1.0.0")
+      plugin_should_be_installed("foo")
+    end
+
     it "install only plugins not installed yet listed in gemfile" do
       gemfile <<-G
         source '#{file_uri_for(gem_repo2)}'