Add new Rails/DateAndTimeColumnName cop

changelog/new_add_new_date_and_time_column_name_cop.md

@@ -0,0 +1 @@
+* [#335](https://github.com/rubocop/rubocop-rails/pull/335): Add new `Rails/DateAndTimeColumnName` cop. ([@fatkodima][])

config/default.yml

@@ -344,6 +344,17 @@ Rails/Date:
     - flexible
   AllowToTime: true
 
+Rails/DateAndTimeColumnName:
+  Description: >-
+                Enforces date/time columns naming conventions.
+                Specifically, `date` column should end with `_on` suffix,
+                `datetime` and `timestamp` - with `_at` suffix,
+                `time` - with `_time` suffix.
+  Enabled: pending
+  VersionAdded: '<<next>>'
+  Include:
+    - db/**/*.rb
+
 Rails/DefaultScope:
   Description: 'Avoid use of `default_scope`.'
   Enabled: false

lib/rubocop/cop/rails/date_and_time_column_name.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # Enforces date/time columns naming conventions.
+      # Specifically, `date` column should end with `_on` suffix,
+      # `datetime` and `timestamp` - with `_at` suffix,
+      # `time` - with `_time` suffix.
+      #
+      # @example
+      #   # bad
+      #   add_column :orders, :created_on, :datetime
+      #   t.column :visited_at, :date
+      #   t.time :start_at
+      #
+      #   # good
+      #   add_column :orders, :created_at, :datetime
+      #   t.column :visited_on, :date
+      #   t.time :start_time
+      #
+      class DateAndTimeColumnName < Base
+        prepend MigrationsHelper
+
+        MSG = 'Name `%<type>s` columns with `%<suffix>s` suffixes.'
+        TYPE_TO_SUFFIX = { datetime: '_at', timestamp: '_at', date: '_on', time: '_time' }.freeze
+
+        def on_send(node)
+          return unless in_migration?(node)
+
+          column_name, type = column_name_and_type(node)
+          return unless column_name
+
+          suffix = TYPE_TO_SUFFIX[type]
+          return if !suffix || column_name.value.to_s.end_with?(suffix)
+
+          message = format(MSG, type: type, suffix: suffix)
+          add_offense(column_name, message: message)
+        end
+
+        private
+
+        def column_name_and_type(node)
+          case node.method_name
+          when :add_column
+            _table_name, column_name, type, = *node.arguments
+            type = type.value
+          when :column
+            column_name, type, = *node.arguments
+            type = type.value
+          when *TYPE_TO_SUFFIX.keys
+            column_name = node.first_argument
+            type = node.method_name
+          end
+
+          [column_name, type]
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -35,6 +35,7 @@
 require_relative 'rails/create_table_with_timestamps'
 require_relative 'rails/dangerous_column_names'
 require_relative 'rails/date'
+require_relative 'rails/date_and_time_column_name'
 require_relative 'rails/default_scope'
 require_relative 'rails/delegate'
 require_relative 'rails/delegate_allow_blank'

spec/rubocop/cop/rails/date_and_time_column_name_spec.rb

@@ -0,0 +1,157 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::DateAndTimeColumnName, :config do
+  described_class::TYPE_TO_SUFFIX.each do |type, suffix|
+    context 'when `add_column` method' do
+      it "registers an offense for `#{type}` column without `#{suffix}` suffix" do
+        source = <<~RUBY
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              add_column :table_name, :column_name_without_suffix, :#{type}
+            end
+          end
+        RUBY
+
+        offenses = inspect_source(source)
+        expect(offenses.count).to eq(1)
+      end
+
+      it "does not register an offense for `#{type}` column with `#{suffix}` suffix" do
+        expect_no_offenses(<<~RUBY)
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              add_column :table_name, :column_name_#{suffix}, :#{type}
+            end
+          end
+        RUBY
+      end
+    end
+
+    context 'when `column` method' do
+      it "registers an offense for `#{type}` column without `#{suffix}` suffix" do
+        source = <<~RUBY
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              create_table :table_name do |t|
+                t.column :column_name_without_suffix, :#{type}
+              end
+            end
+          end
+        RUBY
+
+        offenses = inspect_source(source)
+        expect(offenses.count).to eq(1)
+      end
+
+      it "does not register an offense for `#{type}` column with `#{suffix}` suffix" do
+        expect_no_offenses(<<~RUBY)
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              create_table :table_name do |t|
+                t.column :column_name_#{suffix}, :#{type}
+              end
+            end
+          end
+        RUBY
+      end
+
+      it 'does not register an offense when non date column is used' do
+        expect_no_offenses(<<~RUBY)
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              create_table :table_name do |t|
+                t.column :column_name, :integer
+              end
+            end
+          end
+        RUBY
+      end
+    end
+
+    context 'when `t.<type>` method' do
+      it "registers an offense for `#{type}` column without `#{suffix}` suffix" do
+        source = <<~RUBY
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              create_table :table_name do |t|
+                t.#{type} :column_name_without_suffix
+              end
+            end
+          end
+        RUBY
+
+        offenses = inspect_source(source)
+        expect(offenses.count).to eq(1)
+      end
+
+      it "does not register an offense for `#{type}` column with `#{suffix}` suffix" do
+        expect_no_offenses(<<~RUBY)
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              create_table :table_name do |t|
+                t.#{type} :column_name_#{suffix}
+              end
+            end
+          end
+        RUBY
+      end
+
+      it 'does not register an offense when non date column is used' do
+        expect_no_offenses(<<~RUBY)
+          class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+            def change
+              create_table :table_name do |t|
+                t.integer :column_name
+              end
+            end
+          end
+        RUBY
+      end
+    end
+  end
+
+  it 'does not register an offense when `add_column` with non date column is used' do
+    expect_no_offenses(<<~RUBY)
+      class AddColumnNameToTableName < ActiveRecord::Migration[6.0]
+        def change
+          add_column :table_name, :column_name, :integer
+        end
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when not inside migration' do
+    expect_no_offenses(<<~RUBY)
+      class Foo
+        add_column :table_name, :column_name, :datetime
+      end
+    RUBY
+  end
+
+  context 'MigratedSchemaVersion is used' do
+    let(:config) do
+      RuboCop::Config.new('AllCops' => { 'MigratedSchemaVersion' => '20211007000001' })
+    end
+
+    it 'registers an offense for newer migrations' do
+      expect_offense(<<~RUBY, 'db/migrate/20211007000002_add_created_on_to_orders.rb')
+        class AddCreatedOnToOrders < ActiveRecord::Migration[6.0]
+          def change
+            add_column :orders, :created_on, :datetime
+                                ^^^^^^^^^^^ Name `datetime` columns with `_at` suffixes.
+          end
+        end
+      RUBY
+    end
+
+    it 'does not register an offense for older migrations' do
+      expect_no_offenses(<<~RUBY, 'db/migrate/20211007000001_add_column_to_table_name.rb')
+        class AddCreatedOnToOrders < ActiveRecord::Migration[6.0]
+          def change
+            add_column :orders, :created_on, :datetime
+          end
+        end
+      RUBY
+    end
+  end
+end