Switch InstallCommand to use RequestSet to install

Gem::DependencyInstaller is still used to set up the RequestSet but the
installation actions occur via RequestSet#install.  This makes --explain
and gem installation use the same gem installation order.

This also moves documentation generation into RequestSet#install.

This makes explain order and install order the same as part of #813

lib/rubygems/commands/install_command.rb

@@ -216,10 +216,9 @@ def install_gem name, version # :nodoc:
       install_gem_without_dependencies name, req
     else
       inst = Gem::DependencyInstaller.new options
+      request_set = inst.resolve_dependencies name, req
 
       if options[:explain]
-        request_set = inst.resolve_dependencies name, req
-
         puts "Gems to install:"
 
         request_set.sorted_requests.each do |s|
@@ -228,11 +227,9 @@ def install_gem name, version # :nodoc:
 
         return
       else
-        inst.install name, req
+        @installed_specs.concat request_set.install options
       end
 
-      @installed_specs.push(*inst.installed_gems)
-
       show_install_errors inst.errors
     end
   end

lib/rubygems/request_set.rb

@@ -130,7 +130,8 @@ def import deps
 
   def install options, &block # :yields: request, installer
     if dir = options[:install_dir]
-      return install_into dir, false, options, &block
+      specs = install_into dir, false, options, &block
+      return specs
     end
 
     cache_dir = options[:cache_dir] || Gem.dir
@@ -157,6 +158,17 @@ def install options, &block # :yields: request, installer
     end
 
     specs
+  ensure
+    raise if $!
+    return specs if options[:gemdeps]
+
+    require 'rubygems/dependency_installer'
+    inst = Gem::DependencyInstaller.new options
+    inst.installed_gems.replace specs
+
+    Gem.done_installing_hooks.each do |hook|
+      hook.call inst, specs
+    end unless Gem.done_installing_hooks.empty?
   end
 
   ##

test/rubygems/test_gem_dependency_installer.rb

@@ -293,7 +293,7 @@ def test_install_dependency
 
     Gem.done_installing do |installer, specs|
       done_installing_ran = true
-      assert_equal inst, installer
+      refute_nil installer
       assert_equal [@a1, @b1], specs
     end
 

test/rubygems/test_gem_request_set.rb

@@ -42,6 +42,12 @@ def test_install_from_gemdeps
       fetcher.gem 'a', 2
     end
 
+    done_installing_ran = false
+
+    Gem.done_installing do |installer, specs|
+      done_installing_ran = true
+    end
+
     rs = Gem::RequestSet.new
     installed = []
 
@@ -61,6 +67,7 @@ def test_install_from_gemdeps
     assert_path_exists 'gem.deps.rb.lock'
 
     assert rs.remote
+    refute done_installing_ran
   end
 
   def test_install_from_gemdeps_install_dir
@@ -335,6 +342,12 @@ def test_sorted_requests
   end
 
   def test_install
+    done_installing_ran = false
+
+    Gem.done_installing do
+      done_installing_ran = true
+    end
+
     spec_fetcher do |fetcher|
       fetcher.gem "a", "1", "b" => "= 1"
       fetcher.gem "b", "1"
@@ -363,6 +376,8 @@ def test_install
     assert_path_exists File.join @gemhome, 'specifications', 'b-1.gemspec'
 
     assert_equal %w[b-1 a-1], installed.map { |s| s.full_name }
+
+    assert done_installing_ran
   end
 
   def test_install_into