Factorize bin/update in bin/setup, and make bin/setup idempotent

`bin/setup` and `bin/update` are currently almost the same file. The
only thing that keeps them apart is that one is running `bin/rails
db:setup` and the other `bin/rails db:migrate`.

I'm suggesting here that they should be a unique script, which needs to
be idempotent.

- New to a project, need to get started? `bin/setup`
- Need to install new dependencies that were added recently? `bin/setup`.

Before deprecating `bin/update`, I'm suggesting we just have it call
`bin/setup`.

railties/lib/rails/generators/rails/app/templates/bin/setup.tt

@@ -8,7 +8,8 @@ def system!(*args)
 end
 
 FileUtils.chdir APP_ROOT do
-  # This script is a starting point to setup your application.
+  # This script is a way to setup or update your development environment automatically.
+  # This script is idempotent, so that you can run it at anytime and get an expectable outcome.
   # Add necessary setup steps to this file.
 
   puts '== Installing dependencies =='
@@ -27,7 +28,7 @@ FileUtils.chdir APP_ROOT do
   # end
 
   puts "\n== Preparing database =="
-  system! 'bin/rails db:setup'
+  system! 'bin/rails db:prepare'
 <% end -%>
 
   puts "\n== Removing old logs and tempfiles =="

railties/lib/rails/generators/rails/app/templates/bin/update.tt

@@ -1,33 +0,0 @@
-require 'fileutils'
-
-# path to your application root.
-APP_ROOT = File.expand_path('..', __dir__)
-
-def system!(*args)
-  system(*args) || abort("\n== Command #{args} failed ==")
-end
-
-FileUtils.chdir APP_ROOT do
-  # This script is a way to update your development environment automatically.
-  # Add necessary update steps to this file.
-
-  puts '== Installing dependencies =='
-  system! 'gem install bundler --conservative'
-  system('bundle check') || system!('bundle install')
-<% unless options.skip_javascript? -%>
-
-  # Install JavaScript dependencies
-  # system('bin/yarn')
-<% end -%>
-<% unless options.skip_active_record? -%>
-
-  puts "\n== Updating database =="
-  system! 'rails db:migrate'
-<% end -%>
-
-  puts "\n== Removing old logs and tempfiles =="
-  system! 'rails log:clear tmp:clear'
-
-  puts "\n== Restarting application server =="
-  system! 'rails restart'
-end

railties/test/application/bin_setup_test.rb

@@ -6,21 +6,12 @@ module ApplicationTests
   class BinSetupTest < ActiveSupport::TestCase
     include ActiveSupport::Testing::Isolation
 
-    def setup
-      build_app
-    end
-
-    def teardown
-      teardown_app
-    end
+    setup :build_app
+    teardown :teardown_app
 
     def test_bin_setup
       Dir.chdir(app_path) do
-        app_file "db/schema.rb", <<-RUBY
-          ActiveRecord::Schema.define(version: 20140423102712) do
-            create_table(:articles) {}
-          end
-        RUBY
+        rails "generate", "model", "article"
 
         list_tables = lambda { rails("runner", "p ActiveRecord::Base.connection.tables").strip }
         File.write("log/test.log", "zomg!")
@@ -28,15 +19,20 @@ module ApplicationTests
         assert_equal "[]", list_tables.call
         assert_equal 5, File.size("log/test.log")
         assert_not File.exist?("tmp/restart.txt")
+
         `bin/setup 2>&1`
         assert_equal 0, File.size("log/test.log")
-        assert_equal '["articles", "schema_migrations", "ar_internal_metadata"]', list_tables.call
+        assert_equal '["schema_migrations", "ar_internal_metadata", "articles"]', list_tables.call
         assert File.exist?("tmp/restart.txt")
       end
     end
 
     def test_bin_setup_output
       Dir.chdir(app_path) do
+        # SQLite3 seems to auto-create the database on first checkout.
+        rails "db:system:change", "--to=postgresql"
+        rails "db:drop"
+
         app_file "db/schema.rb", ""
 
         output = `bin/setup 2>&1`
@@ -53,8 +49,8 @@ module ApplicationTests
           The Gemfile's dependencies are satisfied
 
           == Preparing database ==
-          Created database 'db/development.sqlite3'
-          Created database 'db/test.sqlite3'
+          Created database 'app_development'
+          Created database 'app_test'
 
           == Removing old logs and tempfiles ==