Add frozen option for CI environment (#603)

Add --frozen option to abort instead of write annotation.
This is mainly for CI environment to detect missing annotation.
Similar motivation with bundle install --frozen.

works like:
```
$ rake db:migrate frozen=yes

annotate error. spec/models/user_spec.rb needs to be updated, but annotate was run with `--frozen
```

README.rdoc

@@ -203,6 +203,7 @@ you can do so with a simple environment variable, instead of editing the
         -f [bare|rdoc|markdown],         Render Schema Infomation as plain/RDoc/Markdown
             --format
             --force                      Force new annotations even if there are no changes.
+            --frozen                     Do not allow to change annotations. Exits non-zero if there are going to be changes to files.
             --timestamp                  Include timestamp in (routes) annotation
             --trace                      If unable to annotate a file, print the full stack trace, not just the exception message.
         -I, --ignore-columns REGEX       don't annotate columns that match a given REGEX (i.e., `annotate -I '^(id|updated_at|created_at)'`

bin/annotate

@@ -22,6 +22,7 @@ has_set_position = {}
 target_action = :do_annotations
 positions = %w(before top after bottom)
 
+# rubocop:disable Metrics/BlockLength
 OptionParser.new do |opts|
   opts.banner = 'Usage: annotate [options] [model_file]*'
 
@@ -170,6 +171,10 @@ OptionParser.new do |opts|
     ENV['force'] = 'yes'
   end
 
+  opts.on('--frozen', 'Do not allow to change annotations. Exits non-zero if there are going to be changes to files.') do
+    ENV['frozen'] = 'yes'
+  end
+
   opts.on('--timestamp', 'Include timestamp in (routes) annotation') do
     ENV['timestamp'] = 'true'
   end
@@ -202,6 +207,7 @@ OptionParser.new do |opts|
     ENV['with_comment'] = 'true'
   end
 end.parse!
+# rubocop:enable Metrics/BlockLength
 
 options = Annotate.setup_options(
   is_rake: ENV['is_rake'] && !ENV['is_rake'].empty?

lib/annotate.rb

@@ -29,8 +29,8 @@ module Annotate
   FLAG_OPTIONS = [
     :show_indexes, :simple_indexes, :include_version, :exclude_tests,
     :exclude_fixtures, :exclude_factories, :ignore_model_sub_dir,
-    :format_bare, :format_rdoc, :format_markdown, :sort, :force, :trace,
-    :timestamp, :exclude_serializers, :classified_sort,
+    :format_bare, :format_rdoc, :format_markdown, :sort, :force, :frozen,
+    :trace, :timestamp, :exclude_serializers, :classified_sort,
     :show_foreign_keys, :show_complete_foreign_keys,
     :exclude_scaffolds, :exclude_controllers, :exclude_helpers,
     :exclude_sti_subclasses, :ignore_unknown_models, :with_comment

lib/annotate/annotate_models.rb

@@ -513,6 +513,8 @@ def annotate_one_file(file_name, info_block, position, options = {})
 
       return false if old_columns == new_columns && !options[:force]
 
+      abort "annotate error. #{file_name} needs to be updated, but annotate was run with `--frozen`." if options[:frozen]
+
       # Replace inline the old schema info with the new schema info
       wrapper_open = options[:wrapper_open] ? "# #{options[:wrapper_open]}\n" : ""
       wrapper_close = options[:wrapper_close] ? "# #{options[:wrapper_close]}\n" : ""

lib/generators/annotate/templates/auto_annotate_models.rake

@@ -42,6 +42,7 @@ if Rails.env.development?
       'format_markdown'           => 'false',
       'sort'                      => 'false',
       'force'                     => 'false',
+      'frozen'                    => 'false',
       'classified_sort'           => 'true',
       'trace'                     => 'false',
       'wrapper_open'              => nil,

lib/tasks/annotate_models.rake

@@ -39,6 +39,7 @@ task annotate_models: :environment do
   options[:format_markdown] = Annotate.true?(ENV['format_markdown'])
   options[:sort] = Annotate.true?(ENV['sort'])
   options[:force] = Annotate.true?(ENV['force'])
+  options[:frozen] = Annotate.true?(ENV['frozen'])
   options[:classified_sort] = Annotate.true?(ENV['classified_sort'])
   options[:trace] = Annotate.true?(ENV['trace'])
   options[:wrapper_open] = Annotate.fallback(ENV['wrapper_open'], ENV['wrapper'])

spec/annotate/annotate_models_spec.rb

@@ -1768,6 +1768,25 @@ class User < ActiveRecord::Base
         expect(error_output).to include("/user.rb:2:in `<class:User>'")
       end
     end
+
+    describe 'frozen option' do
+      it "should abort without existing annotation when frozen: true " do
+        expect { annotate_one_file frozen: true }.to raise_error SystemExit, /user.rb needs to be updated, but annotate was run with `--frozen`./
+      end
+
+      it "should abort with different annotation when frozen: true " do
+        annotate_one_file
+        another_schema_info = AnnotateModels.get_schema_info(mock_class(:users, :id, [mock_column(:id, :integer)]), '== Schema Info')
+        @schema_info = another_schema_info
+
+        expect { annotate_one_file frozen: true }.to raise_error SystemExit, /user.rb needs to be updated, but annotate was run with `--frozen`./
+      end
+
+      it "should NOT abort with same annotation when frozen: true " do
+        annotate_one_file
+        expect { annotate_one_file frozen: true }.not_to raise_error
+      end
+    end
   end
 
   describe '.annotate_model_file' do