Implement Pragma::Operation hooks

.rubocop.yml

@@ -26,6 +26,9 @@ Style/BlockDelimiters:
   Exclude:
     - 'spec/**/*'
 
+Style/Documentation:
+  Enabled: false
+
 Layout/AlignParameters:
   EnforcedStyle: with_fixed_indentation
 

lib/pragma/migration.rb

@@ -9,10 +9,45 @@
 require 'pragma/migration/runner'
 require 'pragma/migration/bond'
 require 'pragma/migration/middleware'
+require 'pragma/migration/hooks/operation'
 require 'pragma/migration/gem_version'
 
 module Pragma
   # Provides API payload migrations to support clients on older versions of your API.
   module Migration
+    # The default +user_version_proc+.
+    DEFAULT_USER_VERSION_PROC = lambda do |request|
+      request.get_header('X-Api-Version')
+    end
+
+    class << self
+      # @!attribute [rw] repository
+      #   @return [Pragma::Migration::Repository] your migrations repository
+      #
+      # @!attribute [rw] user_version_proc
+      #   @return [Object] a callable taking a +Rack::Request+ as argument and returning an API
+      #     version identifier
+      attr_accessor :repository
+      attr_writer :user_version_proc
+
+      def user_version_proc
+        @user_version_proc ||= DEFAULT_USER_VERSION_PROC
+      end
+
+      # Returns the user's API version for the given request.
+      #
+      # @param request [Rack::Request] the request
+      #
+      # @return [String] the API version identifier
+      def user_version_from(request)
+        version = user_version_proc.call(request)
+
+        if version && repository.sorted_versions.include?(version)
+          version
+        else
+          repository.sorted_versions.last.number
+        end
+      end
+    end
   end
 end

lib/pragma/migration/hooks/operation.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Pragma
+  module Migration
+    module Hooks
+      module Operation
+        def rolled_migrations(options)
+          build_migration_bond(options).rolled_migrations
+        end
+
+        def applying_migrations(options)
+          build_migration_bond(options).applying_migrations
+        end
+
+        def migration_rolled?(options, migration)
+          build_migration_bond(options).migration_rolled?(migration)
+        end
+
+        def migration_applies?(options, migration)
+          build_migration_bond(options).migration_applies?(migration)
+        end
+
+        private
+
+        def build_migration_bond(options)
+          Bond.new(
+            repository: Pragma::Migration.repository,
+            request: options['rack.request'],
+            user_version: Pragma::Migration.user_version_from(options['rack.request'])
+          )
+        end
+
+        ::Pragma::Operation::Base.prepend(self) if defined?(::Pragma::Operation::Base)
+      end
+    end
+  end
+end

lib/pragma/migration/middleware.rb

@@ -15,20 +15,11 @@ module Migration
     #       request.get_header 'X-Api-Version'
     #     end)
     class Middleware
-      # The default for +user_version_proc+.
-      DEFAULT_VERSION_PROC = lambda do |request|
-        request.get_header('X-Api-Version')
-      end
-
       # Initializes the middleware.
       #
       # @param app [Object] your app
-      # @param repository [Repository] your migration repository
-      # @param user_version_proc [Proc] a proc that takes a request and returns a version number
-      def initialize(app, repository:, user_version_proc: DEFAULT_VERSION_PROC)
+      def initialize(app)
         @app = app
-        @repository = repository
-        @user_version_proc = user_version_proc
       end
 
       # Executes the middleware.
@@ -51,9 +42,9 @@ def call(env)
         original_request = Rack::Request.new(env)
 
         runner = Runner.new(Bond.new(
-          repository: @repository,
+          repository: repository,
           request: original_request,
-          user_version: user_version_from(original_request)
+          user_version: Pragma::Migration.user_version_from(original_request)
         ))
 
         migrated_request = runner.run_upwards
@@ -67,9 +58,8 @@ def call(env)
 
       private
 
-      def user_version_from(request)
-        version = @user_version_proc.call(request)
-        @repository.sorted_versions.include?(version) ? version : @repository.sorted_versions.last
+      def repository
+        Pragma::Migration.repository
       end
     end
   end

pragma-migration.gemspec

@@ -25,6 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'rack', '~> 2.0'
 
   spec.add_development_dependency 'coveralls'
+  spec.add_development_dependency 'pragma-operation'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'rspec'
   spec.add_development_dependency 'rubocop'

spec/pragma/migration/hooks/operation_spec.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+RSpec.describe Pragma::Migration::Hooks::Operation do
+  subject(:result) do
+    operation_klass.call(
+      {},
+      {
+        'rack.request' => Rack::Request.new('X-Test-Api-Version' => api_version)
+      }
+    )
+  end
+
+  before do
+    module API
+      module Migration
+        class SendNewsletterAutomatically < Pragma::Migration::Base
+        end
+      end
+
+      class MigrationRepository < Pragma::Migration::Repository
+        version '2018-07-15'
+
+        version '2018-07-16', [
+          API::Migration::SendNewsletterAutomatically
+        ]
+      end
+    end
+
+    Pragma::Migration.repository = API::MigrationRepository
+
+    Pragma::Migration.user_version_proc = lambda do |request|
+      request.get_header 'X-Test-Api-Version'
+    end
+  end
+
+  let(:operation_klass) do
+    Class.new(Pragma::Operation::Base) do
+      success :check_migrations!
+
+      def check_migrations!(options, **)
+        options['result.migration_rolled'] = migration_rolled?(
+          options,
+          API::Migration::SendNewsletterAutomatically
+        )
+
+        options['result.migration_rolled'] = migration_applies?(
+          options,
+          API::Migration::SendNewsletterAutomatically
+        )
+
+        options['result.rolled_migrations'] = rolled_migrations(options)
+
+        options['result.applying_migrations'] = applying_migrations(options)
+      end
+    end
+  end
+
+  context 'when the migration is not rolled' do
+    let(:api_version) { '2018-07-15' }
+
+    it 'computes whether a migration was rolled' do
+      expect(result['result.migration_rolled']).to eq(false)
+    end
+
+    it 'computes whether a migration applies' do
+      expect(result['result.migration_applies']).to eq(true)
+    end
+
+    it 'returns the correct rolled migrations' do
+      expect(result['result.rolled_migrations']).to eq([])
+    end
+
+    it 'returns the correct applying migrations' do
+      expect(result['result.applying_migrations']).to eq([API::Migration::SendNewsletterAutomatically])
+    end
+  end
+
+  context 'when the migration is rolled' do
+    let(:api_version) { '2018-07-16' }
+
+    it 'marks the newsletter as sent' do
+      expect(result['result.migration_rolled']).to eq(true)
+    end
+
+    it 'computes whether a migration applies' do
+      expect(result['result.migration_applies']).to eq(false)
+    end
+
+    it 'returns the correct rolled migrations' do
+      expect(result['result.rolled_migrations']).to eq([API::Migration::SendNewsletterAutomatically])
+    end
+
+    it 'returns the correct applying migrations' do
+      expect(result['result.applying_migrations']).to eq([])
+    end
+  end
+end

spec/pragma/migration/middleware_spec.rb

@@ -2,12 +2,14 @@
 
 RSpec.describe Pragma::Migration::Middleware do
   subject do
-    described_class.new(app,
-      repository: repository,
-      user_version_proc: (lambda do |request|
-        request.get_header 'X-Test-Api-Version'
-      end)
-    )
+    described_class.new(app)
+  end
+
+  before do
+    Pragma::Migration.repository = repository
+    Pragma::Migration.user_version_proc = lambda do |request|
+      request.get_header 'X-Test-Api-Version'
+    end
   end
 
   let(:app) do

spec/pragma/migration/migration_spec.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+RSpec.describe Pragma::Migration do
+  describe '#repository=' do
+    it 'changes the repository' do
+      expect {
+        subject.repository = 'test'
+      }.to change(subject, :repository).to('test')
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,4 +1,5 @@
 require "bundler/setup"
+require 'pragma/operation'
 require "pragma/migration"
 
 require 'coveralls'