[Fix rubocop#486] Add new Rails/ExpandedDateRange cop

Fixes rubocop#486.

This PR adds new `Rails/ExpandedDateRange` cop that checks for expanded date range.
It only compatible `..` range is targeted. Incompatible `...` range is ignored.

```ruby
# bad
date.beginning_of_day..date.end_of_day
date.beginning_of_week..date.end_of_week
date.beginning_of_month..date.end_of_month
date.beginning_of_quarter..date.end_of_quarter
date.beginning_of_year..date.end_of_year

# good
date.all_day
date.all_week
date.all_month
date.all_quarter
date.all_year
```

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### New features
+
+* [#486](https://github.com/rubocop/rubocop-rails/issues/486): Add new `Rails/ExpandedDateRange` cop. ([@koic][])
+
 ### Bug fixes
 
 * [#482](https://github.com/rubocop/rubocop-rails/pull/482): Fix a false positive for `Rails/RelativeDateConstant` when assigning (hashes/arrays/etc)-containing procs to a constant. ([@jdelStrother][])

config/default.yml

@@ -287,6 +287,11 @@ Rails/Exit:
   Exclude:
     - lib/**/*.rake
 
+Rails/ExpandedDateRange:
+  Description: 'Checks for expanded date range.'
+  Enabled: pending
+  VersionAdded: '2.11'
+
 Rails/FilePath:
   Description: 'Use `Rails.root.join` for file path joining.'
   Enabled: true

docs/modules/ROOT/pages/cops.adoc

@@ -44,6 +44,7 @@ based on the https://rails.rubystyle.guide/[Rails Style Guide].
 * xref:cops_rails.adoc#railsenvironmentcomparison[Rails/EnvironmentComparison]
 * xref:cops_rails.adoc#railsenvironmentvariableaccess[Rails/EnvironmentVariableAccess]
 * xref:cops_rails.adoc#railsexit[Rails/Exit]
+* xref:cops_rails.adoc#railsexpandeddaterange[Rails/ExpandedDateRange]
 * xref:cops_rails.adoc#railsfilepath[Rails/FilePath]
 * xref:cops_rails.adoc#railsfindby[Rails/FindBy]
 * xref:cops_rails.adoc#railsfindbyid[Rails/FindById]

docs/modules/ROOT/pages/cops_rails.adoc

@@ -1443,6 +1443,40 @@ raise 'a bad error has happened'
 | Array
 |===
 
+== Rails/ExpandedDateRange
+
+|===
+| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+
+| Pending
+| Yes
+| Yes
+| 2.11
+| -
+|===
+
+This cop checks for expanded date range. It only compatible `..` range is targeted.
+Incompatible `...` range is ignored.
+
+=== Examples
+
+[source,ruby]
+----
+# bad
+date.beginning_of_day..date.end_of_day
+date.beginning_of_week..date.end_of_week
+date.beginning_of_month..date.end_of_month
+date.beginning_of_quarter..date.end_of_quarter
+date.beginning_of_year..date.end_of_year
+
+# good
+date.all_day
+date.all_week
+date.all_month
+date.all_quarter
+date.all_year
+----
+
 == Rails/FilePath
 
 |===

lib/rubocop/cop/rails/expanded_date_range.rb

@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # This cop checks for expanded date range. It only compatible `..` range is targeted.
+      # Incompatible `...` range is ignored.
+      #
+      # @example
+      #   # bad
+      #   date.beginning_of_day..date.end_of_day
+      #   date.beginning_of_week..date.end_of_week
+      #   date.beginning_of_month..date.end_of_month
+      #   date.beginning_of_quarter..date.end_of_quarter
+      #   date.beginning_of_year..date.end_of_year
+      #
+      #   # good
+      #   date.all_day
+      #   date.all_week
+      #   date.all_month
+      #   date.all_quarter
+      #   date.all_year
+      #
+      class ExpandedDateRange < Base
+        extend TargetRailsVersion
+        extend AutoCorrector
+
+        MSG = 'Use `%<preferred_method>s` instead.'
+
+        minimum_target_rails_version 5.1
+
+        def_node_matcher :expanded_date_range, <<~PATTERN
+          (irange
+            (send
+              $_ {:beginning_of_day :beginning_of_week :beginning_of_month :beginning_of_quarter :beginning_of_year})
+            (send
+              $_ {:end_of_day :end_of_week :end_of_month :end_of_quarter :end_of_year}))
+        PATTERN
+
+        PREFERRED_METHODS = {
+          beginning_of_day: 'all_day',
+          beginning_of_week: 'all_week',
+          beginning_of_month: 'all_month',
+          beginning_of_quarter: 'all_quarter',
+          beginning_of_year: 'all_year'
+        }.freeze
+
+        MAPPED_DATE_RANGE_METHODS = {
+          beginning_of_day: :end_of_day,
+          beginning_of_week: :end_of_week,
+          beginning_of_month: :end_of_month,
+          beginning_of_quarter: :end_of_quarter,
+          beginning_of_year: :end_of_year
+        }.freeze
+
+        def on_irange(node)
+          return unless expanded_date_range(node)
+
+          begin_node = node.begin
+          end_node = node.end
+          return unless same_receiver?(begin_node, end_node)
+
+          beginning_method = begin_node.method_name
+          end_method = end_node.method_name
+          return unless use_mapped_methods?(beginning_method, end_method)
+
+          preferred_method = "#{begin_node.receiver.source}.#{PREFERRED_METHODS[beginning_method]}"
+
+          add_offense(node, message: format(MSG, preferred_method: preferred_method)) do |corrector|
+            corrector.replace(node, preferred_method)
+          end
+        end
+
+        private
+
+        def same_receiver?(begin_node, end_node)
+          begin_node.receiver.source == end_node.receiver.source
+        end
+
+        def use_mapped_methods?(beginning_method, end_method)
+          MAPPED_DATE_RANGE_METHODS[beginning_method] == end_method
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -33,6 +33,7 @@
 require_relative 'rails/environment_comparison'
 require_relative 'rails/environment_variable_access'
 require_relative 'rails/exit'
+require_relative 'rails/expanded_date_range'
 require_relative 'rails/file_path'
 require_relative 'rails/find_by'
 require_relative 'rails/find_by_id'

spec/rubocop/cop/rails/expanded_date_range_spec.rb

@@ -0,0 +1,146 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::ExpandedDateRange, :config do
+  context 'Rails >= 5.1', :rails51 do
+    it 'registers and corrects an offense when using `date.beginning_of_day..date.end_of_day`' do
+      expect_offense(<<~RUBY)
+        date.beginning_of_day..date.end_of_day
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_day` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        date.all_day
+      RUBY
+    end
+
+    it 'registers and corrects an offense when using `date.beginning_of_week..date.end_of_week`' do
+      expect_offense(<<~RUBY)
+        date.beginning_of_week..date.end_of_week
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_week` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        date.all_week
+      RUBY
+    end
+
+    it 'registers and corrects an offense when using `date.beginning_of_month..date.end_of_month`' do
+      expect_offense(<<~RUBY)
+        date.beginning_of_month..date.end_of_month
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_month` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        date.all_month
+      RUBY
+    end
+
+    it 'registers and corrects an offense when using `date.beginning_of_quarter..date.end_of_quarter`' do
+      expect_offense(<<~RUBY)
+        date.beginning_of_quarter..date.end_of_quarter
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_quarter` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        date.all_quarter
+      RUBY
+    end
+
+    it 'registers and corrects an offense when using `date.beginning_of_year..date.end_of_year`' do
+      expect_offense(<<~RUBY)
+        date.beginning_of_year..date.end_of_year
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_year` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        date.all_year
+      RUBY
+    end
+
+    it 'registers and corrects an offense when using an expanded date range as a method argument' do
+      expect_offense(<<~RUBY)
+        Model.do_something(foo_at: date.beginning_of_day..date.end_of_day)
+                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_day` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        Model.do_something(foo_at: date.all_day)
+      RUBY
+    end
+
+    it 'registers and corrects an offense when assigning expanded date range' do
+      expect_offense(<<~RUBY)
+        foo_at = date.beginning_of_day..date.end_of_day
+                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date.all_day` instead.
+        Model.find_by(foo_at: foo_at)
+      RUBY
+
+      expect_correction(<<~RUBY)
+        foo_at = date.all_day
+        Model.find_by(foo_at: foo_at)
+      RUBY
+    end
+
+    it 'registers and corrects an offense when using multiple expanded date range conditions' do
+      expect_offense(<<~RUBY)
+        Model.where(foo_at: date1.beginning_of_week..date1.end_of_week, bar_at: date2.beginning_of_year..date2.end_of_year)
+                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date1.all_week` instead.
+                                                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `date2.all_year` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        Model.where(foo_at: date1.all_week, bar_at: date2.all_year)
+      RUBY
+    end
+
+    it 'does not register an offense when using `...` range syntax' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_day...date.end_of_day
+      RUBY
+    end
+
+    it 'does not register an offense when variables are different at the beginning and end of the range' do
+      expect_no_offenses(<<~RUBY)
+        date1.beginning_of_day..date2.end_of_day
+      RUBY
+    end
+
+    it 'does not register an offense when unmapped methods are at the beginning and end of the range' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_day..date.end_of_year
+      RUBY
+    end
+  end
+
+  context 'Rails <= 5.0', :rails50 do
+    it 'does not register an offense when using `date.beginning_of_day..date.end_of_day`' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_day..date.end_of_day
+      RUBY
+    end
+
+    it 'does not register an offense when using `date.beginning_of_week..date.end_of_week`' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_week..date.end_of_week
+      RUBY
+    end
+
+    it 'does not register an offense when using `date.beginning_of_month..date.end_of_month`' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_month..date.end_of_month
+      RUBY
+    end
+
+    it 'does not register an offense when using `date.beginning_of_quarter..date.end_of_quarter`' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_quarter..date.end_of_quarter
+      RUBY
+    end
+
+    it 'does not register an offense when using `date.beginning_of_year..date.end_of_year`' do
+      expect_no_offenses(<<~RUBY)
+        date.beginning_of_year..date.end_of_year
+      RUBY
+    end
+  end
+end