Merge pull request #574 from MaximeDucheneS/add_table_name_cop

Add `TableName` cop

CHANGELOG.md

@@ -531,6 +531,7 @@
 [@skryukov]: https://github.com/skryukov
 [@johnsyweb]: https://github.com/johnsyweb
 [@theunraveler]: https://github.com/theunraveler
+[@MaximeDucheneS]: https://github.com/MaximeDucheneS
 [@pirj]: https://github.com/pirj
 [@vitormd]: https://github.com/vitormd
 [@mattmccormick]: https://github.com/mattmccormick

changelog/new_table_name_assignment_cop.md

@@ -0,0 +1 @@
+* [#574](https://github.com/rubocop/rubocop-rails/pull/574): Add new `Rails/TableNameAssignment` cop. ([@MaximeDucheneS][])

config/default.yml

@@ -868,6 +868,15 @@ Rails/SquishedSQLHeredocs:
   # to be preserved in order to work, thus auto-correction is not safe.
   SafeAutoCorrect: false
 
+Rails/TableNameAssignment:
+  Description: >-
+    Do not use `self.table_name =`. Use Inflections or `table_name_prefix` instead.
+  StyleGuide: 'https://rails.rubystyle.guide/#keep-ar-defaults'
+  Enabled: false
+  VersionAdded: '<<next>>'
+  Include:
+    - app/models/**/*.rb
+
 Rails/TimeZone:
   Description: 'Checks the correct usage of time zone aware methods.'
   StyleGuide: 'https://rails.rubystyle.guide#time'

docs/modules/ROOT/pages/cops.adoc

@@ -105,6 +105,7 @@ based on the https://rails.rubystyle.guide/[Rails Style Guide].
 * xref:cops_rails.adoc#railsshorti18n[Rails/ShortI18n]
 * xref:cops_rails.adoc#railsskipsmodelvalidations[Rails/SkipsModelValidations]
 * xref:cops_rails.adoc#railssquishedsqlheredocs[Rails/SquishedSQLHeredocs]
+* xref:cops_rails.adoc#railstablenameassignment[Rails/TableNameAssignment]
 * xref:cops_rails.adoc#railstimezone[Rails/TimeZone]
 * xref:cops_rails.adoc#railstimezoneassignment[Rails/TimeZoneAssignment]
 * xref:cops_rails.adoc#railsuniqbeforepluck[Rails/UniqBeforePluck]

docs/modules/ROOT/pages/cops_rails.adoc

@@ -4922,6 +4922,59 @@ SQL
 
 * https://rails.rubystyle.guide/#squished-heredocs
 
+== Rails/TableNameAssignment
+
+|===
+| Enabled by default | Safe | Supports autocorrection | Version Added | Version Changed
+
+| Disabled
+| Yes
+| No
+| 2.13
+| -
+|===
+
+This cop enforces the absence of explicit table name assignment.
+
+`self.table_name=` should only be used for very good reasons,
+such as not having control over the database, or working
+on a legacy project.
+
+If you need to change how your model's name is translated to
+a table name, you may want to look at Inflections:
+https://api.rubyonrails.org/classes/ActiveSupport/Inflector/Inflections.html
+
+If you wish to add a prefix in front of your model, or wish to change
+the default prefix, `self.table_name_prefix` might better suit your needs:
+https://api.rubyonrails.org/classes/ActiveRecord/ModelSchema.html#method-c-table_name_prefix-3D
+
+
+STI base classes named `Base` are ignored by this cop.
+For more information: https://api.rubyonrails.org/classes/ActiveRecord/Inheritance.html
+
+=== Examples
+
+[source,ruby]
+----
+  # bad
+  self.table_name = 'some_table_name'
+  self.table_name = :some_other_name
+----
+
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| Exclude
+| `spec/**/*`, `db/migrate/*.rb`
+| Array
+|===
+
+=== References
+
+* https://rails.rubystyle.guide/#keep-ar-defaults
+
 == Rails/TimeZone
 
 |===

lib/rubocop/cop/rails/table_name_assignment.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # This cop enforces the absence of explicit table name assignment.
+      #
+      # `self.table_name=` should only be used for very good reasons,
+      # such as not having control over the database, or working
+      # on a legacy project.
+      #
+      # If you need to change how your model's name is translated to
+      # a table name, you may want to look at Inflections:
+      # https://api.rubyonrails.org/classes/ActiveSupport/Inflector/Inflections.html
+      #
+      # If you wish to add a prefix in front of your model, or wish to change
+      # the default prefix, `self.table_name_prefix` might better suit your needs:
+      # https://api.rubyonrails.org/classes/ActiveRecord/ModelSchema.html#method-c-table_name_prefix-3D
+      #
+      # STI base classes named `Base` are ignored by this cop.
+      # For more information: https://api.rubyonrails.org/classes/ActiveRecord/Inheritance.html
+      #
+      # @example
+      #   # bad
+      #   self.table_name = 'some_table_name'
+      #   self.table_name = :some_other_name
+      class TableNameAssignment < Base
+        include ActiveRecordHelper
+
+        MSG = 'Do not use `self.table_name =`.'
+
+        def_node_matcher :base_class?, <<~PATTERN
+          (class (const ... :Base) ...)
+        PATTERN
+
+        def on_class(class_node)
+          return if base_class?(class_node)
+
+          find_set_table_name(class_node).each { |node| add_offense(node) }
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -104,6 +104,7 @@
 require_relative 'rails/short_i18n'
 require_relative 'rails/skips_model_validations'
 require_relative 'rails/squished_sql_heredocs'
+require_relative 'rails/table_name_assignment'
 require_relative 'rails/time_zone'
 require_relative 'rails/time_zone_assignment'
 require_relative 'rails/uniq_before_pluck'

spec/rubocop/cop/rails/table_name_assignment_spec.rb

@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::TableNameAssignment, :config do
+  context 'when table_name is defined' do
+    context 'when string' do
+      it 'registers an offense' do
+        expect_offense(<<~RUBY)
+          class AModule::SomeModel < ApplicationRecord
+            self.table_name = 'some_other_table_name'
+            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use `self.table_name =`.
+          end
+        RUBY
+      end
+    end
+
+    context 'when string = foo' do
+      it 'registers an offense' do
+        expect_offense(<<~RUBY)
+          class AModule::SomeModel < ApplicationRecord
+            self.table_name = 'foo'
+            ^^^^^^^^^^^^^^^^^^^^^^^ Do not use `self.table_name =`.
+          end
+        RUBY
+      end
+    end
+
+    context 'when symbol' do
+      it 'registers an offense' do
+        expect_offense(<<~RUBY)
+          class AModule::SomeModel < ApplicationRecord
+            self.table_name = :some_other_table_name
+            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use `self.table_name =`.
+          end
+        RUBY
+      end
+    end
+
+    context 'when symbol = :foo' do
+      it 'registers an offense' do
+        expect_offense(<<~RUBY)
+          class AModule::SomeModel < ApplicationRecord
+            self.table_name = :foo
+            ^^^^^^^^^^^^^^^^^^^^^^ Do not use `self.table_name =`.
+          end
+        RUBY
+      end
+    end
+  end
+
+  context 'when table_name is not defined' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        class AModule::SomeModel < ApplicationRecord
+          has_many :other_thing
+          has_one :parent_thing
+        end
+      RUBY
+    end
+  end
+
+  # Case for STI base classes
+  context 'when class is named `Base`' do
+    context 'when class is declared with module' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          class A::B::Base < ApplicationRecord
+            has_many :other_thing
+            has_one :parent_thing
+
+            self.table_name = 'special_table_name'
+          end
+        RUBY
+      end
+    end
+
+    context 'when class is declared within module' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          module A
+            module B
+              class Base < ApplicationRecord
+                has_many :other_thing
+                has_one :parent_thing
+
+                self.table_name = 'special_table_name'
+              end
+            end
+          end
+        RUBY
+      end
+    end
+  end
+end